* Observations regarding the nature of how the mass of fundamental particles arises from their gravitational and non-gravitational self-interactions.
* How special relativity determines the sign of electromagnetism and gravity.
* Analysis of the gravitational self-interaction (1970); clarified and expanded upon in 2009. (Criticism of this result and a similar one by Feynman in 1995 that shows an out of the box thinking alternative analysis can be found here). And, some related non-obvious observations about the properties of stress energy tensors. Also graviton-graviton scattering drawing on SUGRA (i.e. the gravitational extension of supersymmetry). A new PhD dissertation expands on the seminal work of Arnowitt, Deser and Misner regarding the global conservation properties of GR extrapolating them in a sensible way to localize the GR effects that they discussed globally. This thesis cites the following papers by these collaborators, four from 1959-1961 and one republished in 2008.
* Non-local modifications of GR to explain dark energy effects without a scalar field or f(R) theory.
* A memorial recalling Dirac's work on gravity.
* A no go result on quantum field theories of gravity.
Deser's papers address many fundamental questions in physics with a clarity of exposition that is lacking in many newer publication.
Tuesday, September 30, 2014
Monday, September 29, 2014
Bell Beaker Site Found In NE Poland
Archaeologists appear to have found a site from the Bell Beaker archaeological culture in Northeast Poland, the furthest Northeast that evidence of the culture has been found to date.
The Bell Beaker culture was the defining culture of Western Europe, emanating from Portugal in the Copper Age and early Bronze Age of Western Europe and into Northern Europe. Some people suspect that it was the last major pre-Indo-European culture of the region and that is provided the major shift in the population genetic mix of the region.
Much of Central and Eastern Europe was defined by the Corded Ware archaeological culture while the Bell Beaker culture prevailed to the West.
The Bell Beaker culture was the defining culture of Western Europe, emanating from Portugal in the Copper Age and early Bronze Age of Western Europe and into Northern Europe. Some people suspect that it was the last major pre-Indo-European culture of the region and that is provided the major shift in the population genetic mix of the region.
Much of Central and Eastern Europe was defined by the Corded Ware archaeological culture while the Bell Beaker culture prevailed to the West.
Moscow Experiment Still Believes That They've Seen Neutrinoless Beta Decay
The Moscow experiment still stands by its conclusion that it detected neutrinoless double beta decay ten years ago, even though this conclusion is not supported by numerous other experiments using a similar methodology.
In other news, MOND and other modified gravity theories continue to out perform cold dark matter theories in predicting galactic dynamics with fewer parameters. The paper calls attention to the Renormalization Group in General Relativity (RGGR) theory, which is a modified gravity theory with on more parameter than MOND and one less than cold dark matter theories. RGGR also somewhat outperforms MOND, albeit with one more free parameter. RGGR has slightly outperformed MOND and its relativistic counterpart TeVeS since at least a 2009 comparison.
In other news, MOND and other modified gravity theories continue to out perform cold dark matter theories in predicting galactic dynamics with fewer parameters. The paper calls attention to the Renormalization Group in General Relativity (RGGR) theory, which is a modified gravity theory with on more parameter than MOND and one less than cold dark matter theories. RGGR also somewhat outperforms MOND, albeit with one more free parameter. RGGR has slightly outperformed MOND and its relativistic counterpart TeVeS since at least a 2009 comparison.
Thursday, September 25, 2014
The Fertility Benefits of Lactase Persistance
When a trait confers a selective benefit, i.e. increases the likelihood that someone who has the trait will have more children who reproduce themselves, it increases its share of the gene pool. Few traits have been more powerfully selected for in recent history than lactase persistance.
Pretty much all children can tolerate the lactose in milk, but for individuals who lack lactose persistence genes, drinking unprocessed milk will make you feel "off" and give you the runs. It is hardly a deadly consequence, but it makes drinking milk without processing it into yogurt or cheese to remove the lactose (which provides about a third of the calories in milk and takes additional effort) a not very viable source of nutrition.
Ancient DNA samples reveal that this trait was almost entirely absent in Europe's first wave Neolithic populations. It appears to have arisen someplace in Northern Europe after dairy farming became common. By the end of the Bronze Age, lactase persistence was predominant and lactose intolerance was rare in most European populations.
Clearly, this gene conferred a very powerful selective benefit (or was in close association with something else that conferred such a benefit) in the Copper and Bronze Ages of Europe. But, what exactly was the benefit?
Needless to say, lactase persistence is a trait that doesn't confer much selective advantage before cows are domesticated and dairying become common. An ability to digest milk properly doesn't matter if you have no regular source of milk in your diet.
But, John Hawks hypothesizes that the populations subject to selection, like many third world populations today, was perennially malnourished. In those conditions, once dairy farming was invented, lactase persistent women, due to their increased calorie consumption from milk, are able to bear children about two years earlier and to space their children about three months closer. Thus, lactase persistent women can have one or two more children per lifetime than women who are not, an increase of at least 10% per generation in lifetime fertility.
This may seem modest, but iterated over the thirty-four generation span of a thousand years, this means that populations with lactase persistent women will increase 25 times as rapidly as populations in which women are not lactase persistent. For example, if the population initially consisted of 1 lactase persistent woman for every 25 lactose intolerant women in 3000 BCE, this advantage would shift to the balance to 1 lactase persistent woman for every lactose intolerant woman by 2000 BCE, and to 25 lactase persistent women for every lactose intolerant woman by 1000 BCE. Thus, a 10% lifetime fertility benefit per woman per generation is enough to shift the lactase persistence trait frequency in the population from 3.8% to 96.2% in two thousand years, which is a pretty decent approximation of the change in the frequency of the lactase persistence trait in selected European populations in the time period from 3000 BCE to 1000 BCE.
If there were other fitness benefits in addition to fertility to lactase persistence, such as improved disease immunity, or an increased chance of survival during fairly frequently periods of famine, then the selective benefit would have been even greater.
Of course, there are only certain conditions where lactase persistence confers a strong benefit. As food production gets more reliable and abundant, and the number of calories available per person rises and the marginal benefit of improved nutrition from access to calories from lactose in milk declines.
Thus, it is not surprising that lactase persistence conferred more of a benefit (and hence became more predominant) in Northern Europe, where climate conditions were less well suited to the Fertile Crescent Neolithic package of crops, than in Southern Europe, where the Mediterranean climate was a near perfect match for the circumstances in which these crops were domesticated.
Likewise, it is not surprising that the selective benefit of lactase persistence declined over time as agricultural technologies became more advanced and well adapted to local conditions.
The declining selective advantage is also a function of the logic of the S-shaped logistic curse in which fitness enhancing traits first remain rare due to the small base number of the exponentially growing group, then accelerates, and then slows down again at the tail end of the transition because most people have already transitioned. When almost everybody can process lactose in milk, sparing a little extra food for the people who cannot process it is easier for a community to manage than it is when almost nobody is lactase persistent, so the relative benefit of lactase persistence in the population declines.
Pretty much all children can tolerate the lactose in milk, but for individuals who lack lactose persistence genes, drinking unprocessed milk will make you feel "off" and give you the runs. It is hardly a deadly consequence, but it makes drinking milk without processing it into yogurt or cheese to remove the lactose (which provides about a third of the calories in milk and takes additional effort) a not very viable source of nutrition.
Ancient DNA samples reveal that this trait was almost entirely absent in Europe's first wave Neolithic populations. It appears to have arisen someplace in Northern Europe after dairy farming became common. By the end of the Bronze Age, lactase persistence was predominant and lactose intolerance was rare in most European populations.
Clearly, this gene conferred a very powerful selective benefit (or was in close association with something else that conferred such a benefit) in the Copper and Bronze Ages of Europe. But, what exactly was the benefit?
Needless to say, lactase persistence is a trait that doesn't confer much selective advantage before cows are domesticated and dairying become common. An ability to digest milk properly doesn't matter if you have no regular source of milk in your diet.
But, John Hawks hypothesizes that the populations subject to selection, like many third world populations today, was perennially malnourished. In those conditions, once dairy farming was invented, lactase persistent women, due to their increased calorie consumption from milk, are able to bear children about two years earlier and to space their children about three months closer. Thus, lactase persistent women can have one or two more children per lifetime than women who are not, an increase of at least 10% per generation in lifetime fertility.
This may seem modest, but iterated over the thirty-four generation span of a thousand years, this means that populations with lactase persistent women will increase 25 times as rapidly as populations in which women are not lactase persistent. For example, if the population initially consisted of 1 lactase persistent woman for every 25 lactose intolerant women in 3000 BCE, this advantage would shift to the balance to 1 lactase persistent woman for every lactose intolerant woman by 2000 BCE, and to 25 lactase persistent women for every lactose intolerant woman by 1000 BCE. Thus, a 10% lifetime fertility benefit per woman per generation is enough to shift the lactase persistence trait frequency in the population from 3.8% to 96.2% in two thousand years, which is a pretty decent approximation of the change in the frequency of the lactase persistence trait in selected European populations in the time period from 3000 BCE to 1000 BCE.
If there were other fitness benefits in addition to fertility to lactase persistence, such as improved disease immunity, or an increased chance of survival during fairly frequently periods of famine, then the selective benefit would have been even greater.
Of course, there are only certain conditions where lactase persistence confers a strong benefit. As food production gets more reliable and abundant, and the number of calories available per person rises and the marginal benefit of improved nutrition from access to calories from lactose in milk declines.
Thus, it is not surprising that lactase persistence conferred more of a benefit (and hence became more predominant) in Northern Europe, where climate conditions were less well suited to the Fertile Crescent Neolithic package of crops, than in Southern Europe, where the Mediterranean climate was a near perfect match for the circumstances in which these crops were domesticated.
Likewise, it is not surprising that the selective benefit of lactase persistence declined over time as agricultural technologies became more advanced and well adapted to local conditions.
The declining selective advantage is also a function of the logic of the S-shaped logistic curse in which fitness enhancing traits first remain rare due to the small base number of the exponentially growing group, then accelerates, and then slows down again at the tail end of the transition because most people have already transitioned. When almost everybody can process lactose in milk, sparing a little extra food for the people who cannot process it is easier for a community to manage than it is when almost nobody is lactase persistent, so the relative benefit of lactase persistence in the population declines.
Wednesday, September 24, 2014
Gender Differences In Effective Population Size
Genetic evidence shows that the effective population of men in prehistoric populations was smaller pretty much across the board than the effective population size of women in those populations, although the extent of the discrepancy varied significantly in different places and times.
While I agree that this likely involves men having children with more than one woman in their life, the press release connected to the study confounds the notion of census population, which is boy heavy for children, about equal at sexual maturity, and woman heavy at older ages in modern populations, with effective population size, which is typically several times smaller than census population and has a different technical definition. In particular, effective population size is increased relative to census population when each parent has the same number of children, and is decreased when the number of children per parent is highly varied.
The abstract of the open access paper reads as follows (in selected parts):
If Neanderthal admixture, for example, took place at around the time of this minimum sized ancestral Out of African population, the number of instances of Neanderthal admixture that accounts for the lion's share of Neanderthal ancestry in modern humans today could have arisen from just a couple of human-Neanderthal hybrid births in all of human history at just the right time and place.
The study also notes that some substantial regional subsets of Native American populations have substantially less mtDNA diversity than the New World as a whole.
The likely scenario is not that there were substantially fewer men than women outside isolated moments in the aftermath of wars and the like, although bad hunts in hunter-gatherer societies may have served a similar function, but that a higher percentage of men than of women were excluded from reproduction entirely.
For example, if women, on average have roughly the same number of children per lifetime, but some men have only one or two, while other many have many children, the effective population size of men will be smaller than the effective population size of women, even if on a census basis there are the same number of men and women with children. This could happen, for example, if men were equally likely to have a first wife, but if high status widowers were more likely to remarry upon a wife's death in childbirth, than low status widowers.
Also, my analysis earlier this year at sister blog Wash Park Prophet, of the way that Southern Civil War widows coped historically with the loss of their men, suggests that the capacity of serial monogamy, rather than polygny to cope with imbalances between the number of women and the number of men in a population is greatly underestimated. In that situation:
I suspect that remarriage by men following the losses of their wives in childbirth may have been an important source of the enduring nature of this imbalance across so many different eras and cultures of prehistory. Widowers outnumbered widows during the colonial and revolutionary war eras of the United States, for example.
While I agree that this likely involves men having children with more than one woman in their life, the press release connected to the study confounds the notion of census population, which is boy heavy for children, about equal at sexual maturity, and woman heavy at older ages in modern populations, with effective population size, which is typically several times smaller than census population and has a different technical definition. In particular, effective population size is increased relative to census population when each parent has the same number of children, and is decreased when the number of children per parent is highly varied.
The abstract of the open access paper reads as follows (in selected parts):
Our results confirm the controversial assertion that genetic differences between human populations on a global scale are bigger for the NRY than for mtDNA, although the differences are not as large as previously suggested. More importantly, we find substantial regional variation in patterns of mtDNA versus NRY variation. Model-based simulations indicate very small ancestral effective population sizes (less than 100) for the out-of-Africa migration as well as for many human populations. We also find that the ratio of female effective population size to male effective population size (Nf/Nm) has been greater than one throughout the history of modern humans, and has recently increased due to faster growth in Nf than Nm.Later on, the body of the study elaborates on the ancestral effective population sizes and notes that:
The simulation results suggest a small founding size in Africa of about 60 females and 30 males (all population sizes are effective population sizes); migration out of Africa about 75 kya associated with a bottleneck of around 25 females and 15 males; migrations from this non-African founding population to Oceania 61 kya, to Europe 49 kya, to Central and East Asia 37 kya, and from East Asia to the Americas about 15 kya.Thus, all humans can be traced to a founding population with an effective size of only about 90 individuals, and all non-Africans derived from a subset a population with an effective size of about 40 ancestral individuals. Even if a rule of thumb factor of three was used to convert effective population sizes to census population sizes, in each case were are talking about huge populations derived from tiny villages at quite specific dates in the past.
If Neanderthal admixture, for example, took place at around the time of this minimum sized ancestral Out of African population, the number of instances of Neanderthal admixture that accounts for the lion's share of Neanderthal ancestry in modern humans today could have arisen from just a couple of human-Neanderthal hybrid births in all of human history at just the right time and place.
The study also notes that some substantial regional subsets of Native American populations have substantially less mtDNA diversity than the New World as a whole.
The likely scenario is not that there were substantially fewer men than women outside isolated moments in the aftermath of wars and the like, although bad hunts in hunter-gatherer societies may have served a similar function, but that a higher percentage of men than of women were excluded from reproduction entirely.
For example, if women, on average have roughly the same number of children per lifetime, but some men have only one or two, while other many have many children, the effective population size of men will be smaller than the effective population size of women, even if on a census basis there are the same number of men and women with children. This could happen, for example, if men were equally likely to have a first wife, but if high status widowers were more likely to remarry upon a wife's death in childbirth, than low status widowers.
Also, my analysis earlier this year at sister blog Wash Park Prophet, of the way that Southern Civil War widows coped historically with the loss of their men, suggests that the capacity of serial monogamy, rather than polygny to cope with imbalances between the number of women and the number of men in a population is greatly underestimated. In that situation:
About 18% of white men in the South aged 13 to 43 died in the American Civil War (1861-1865) and Reconstruction, and many more were crippled as a result, for example, with amputated limbs. Yet, by 1890, there was no excess in the number of women never married in the South.The way that people did cope with this imbalance was complex, but de facto polygamy was very rarely the solution adopted.
I suspect that remarriage by men following the losses of their wives in childbirth may have been an important source of the enduring nature of this imbalance across so many different eras and cultures of prehistory. Widowers outnumbered widows during the colonial and revolutionary war eras of the United States, for example.
More Dark Matter and Gravitation Developments
Another point in the case against dark matter.
It is possible to modify or reinterpret the laws of gravity to reproduce essentially all galactic scale phenomena associated with dark matter, although no widely accepted total gravitational modification solution exists at this point.
Dark matter models, meanwhile, are plagued by the absence of any discovered particles that can serve as exotic dark matter, and as required in many models, by the absence of a mechanism for self-interactions within the dark sector or the creation of dark matter particles. Cold dark matters have even more problems.
The latest issue with dark matter models is their failure to produce two separate classes of dwarf galaxies - one with lots of dark matter and one with almost none, with the latter seeming to predominate, contrary to inferred dark matter halo observations.
Kroupa argues that both Cold Dark Matter (CDM) and Warm Dark Matter (WDM) are ruled out by this analysis and by elimination argues that a flaw in the equations of general relativity that describe gravity must account for observed dark matter phenomena.
I don't find Kroupa's analysis to be such an obvious and unequivocal rejection of exotic dark matter. But, the analysis does reveal yet another issue with conventional dark matter theories that must be resolved in any correct theory explaining dark matter phenomena.
Dark Matter Behavior and Modeling
Another new paper suggests important flaws in how the dynamics of galaxies have been modeled in the past. Christiane Frigerio Martins, Jose' Ademir Sales Lima, and Pietro Chimenti argue in "Rotation Curves and Nonextensive Statistics" (September 22, 2014) that the prevailing analysis uses a methodology appropriate only for short-range forces that is beyond its domain of applicability in modeling the gravitational interactions of particles and needs to be revised accordingly.
Another study by Bernardo Cervantes Sodi, Cheng Li and Changbom Park entitled "Dark matter halos of barred disk galaxies" (September 23, 2014) refines existing empirical data regarding the inferred shape of dark matter halos in barred disk galaxies based upon new data. The core result is that "in agreement with previous studies, confirms that the bar fraction does not directly depend on the group/cluster environment, but the dependence exists through its dependence on internal morphology."
So does a study of 13 galaxies for which precision measurements are available by Marc S. Seigar, Benjamin L. Davis, Joel Berrier, Daniel Kennefick, in "Constraining dark matter halo profiles and galaxy formation models using spiral arm morphology. II. Dark and stellar mass concentrations for 13 nearby face-on galaxies" (September 23, 2014). Most notably, the abstract of the paper reports that: "we show that there appears to be a trend (albeit a weak correlation) between spiral arm pitch angle and halo concentration. We discuss implications for the suggested link between supermassive black hole (SMBH) mass and dark halo concentration, using pitch angle as a proxy for SMBH mass." These trends are a fit for those suggested by Deur in his graviton self-interaction model (i.e. a relationship between the magnitude of dark matter effects and overall mass and deviation from spherical symmetry).
Meanwhile, Gerasimos Rigopoulos, in "A Relativistic view on large scale N-body simulations" (September 23, 2014), notes that while Newtonian N-body simulations approximate the general relativistic behavior accurately at the first order, that there are material second order non-linear effects in general relativity that are not captured by such simulations making them inappropriate to use, particularly in very large simulations, without modification.
Dark Matter Creation
One of the strongest warm dark matter candidates is suggested by X-ray observations from galaxy clusters.
The surprise ending to this paper is that the only means of production consistent with the Lyman alpha forest produces unusually slow moving (i.e. "cold") dark matter particles that have the same "small scale" problems as cold dark matter. Despite its low mass, particles produced in this fashion would be cold dark matter, rather than the expected warm dark matter, which is disfavored by astronomy observations such as satellite galaxy abundance.
Thus, the bottom line of the paper is really to disfavor the 3.5 keV X-ray line as a true signal of dark matter decay, because that interpretation, taken to its logical conclusion, produces contradictory data.
BICEP-2 Questioned Again
Finally, a new analysis of the BICEP-2 data in light of Planck dust polarization data adds to the chorus of doubt about the validity of the signal that the experiment claims it observed of primordial gravitational tensor waves. The paper is Marina Cortês, Andrew R Liddle, and David Parkinson, "Tensors, BICEP2, prior dependence, and dust" (September 23, 2014). They state:
It is possible to modify or reinterpret the laws of gravity to reproduce essentially all galactic scale phenomena associated with dark matter, although no widely accepted total gravitational modification solution exists at this point.
Dark matter models, meanwhile, are plagued by the absence of any discovered particles that can serve as exotic dark matter, and as required in many models, by the absence of a mechanism for self-interactions within the dark sector or the creation of dark matter particles. Cold dark matters have even more problems.
The latest issue with dark matter models is their failure to produce two separate classes of dwarf galaxies - one with lots of dark matter and one with almost none, with the latter seeming to predominate, contrary to inferred dark matter halo observations.
The existence of exotic dark matter particles outside the standard model of particle physics constitutes a central hypothesis of the current standard model of cosmology (SMoC). Using a wide range of observational data I outline why this hypothesis cannot be correct for the real Universe. Assuming the SMoC to hold,
(i) the two types of dwarf galaxies, the primordial dwarfs with dark matter and the tidal dwarf galaxies without dark matter, ought to present clear observational differences. But there is no observational evidence for two separate families of dwarfs, neither in terms of their location relative to the baryonic Tully-Fisher relation nor in terms of their radius--mass relation. And, the arrangements in rotating disk-of-satellites, in particular around the Milky Way and Andromeda, has been found to be only consistent with most if not all dwarf satellite galaxies being tidal dwarf galaxies. The highly symmetric structure of the entire Local Group too is inconsistent with its galaxies stemming from a stochastic merger-driven hierarchical buildup over cosmic time.
(ii) Dynamical friction on the expansive and massive dark matter halos is not evident in the data.
Taking the various lines of evidence together, the hypothesis that dynamically relevant exotic dark matter exists needs to be firmly rejected.- Pavel Kroupa, "Lessons from the Local Group (and beyond) on dark matter" (September 22, 2014).
Kroupa argues that both Cold Dark Matter (CDM) and Warm Dark Matter (WDM) are ruled out by this analysis and by elimination argues that a flaw in the equations of general relativity that describe gravity must account for observed dark matter phenomena.
I don't find Kroupa's analysis to be such an obvious and unequivocal rejection of exotic dark matter. But, the analysis does reveal yet another issue with conventional dark matter theories that must be resolved in any correct theory explaining dark matter phenomena.
Dark Matter Behavior and Modeling
Another new paper suggests important flaws in how the dynamics of galaxies have been modeled in the past. Christiane Frigerio Martins, Jose' Ademir Sales Lima, and Pietro Chimenti argue in "Rotation Curves and Nonextensive Statistics" (September 22, 2014) that the prevailing analysis uses a methodology appropriate only for short-range forces that is beyond its domain of applicability in modeling the gravitational interactions of particles and needs to be revised accordingly.
Another study by Bernardo Cervantes Sodi, Cheng Li and Changbom Park entitled "Dark matter halos of barred disk galaxies" (September 23, 2014) refines existing empirical data regarding the inferred shape of dark matter halos in barred disk galaxies based upon new data. The core result is that "in agreement with previous studies, confirms that the bar fraction does not directly depend on the group/cluster environment, but the dependence exists through its dependence on internal morphology."
So does a study of 13 galaxies for which precision measurements are available by Marc S. Seigar, Benjamin L. Davis, Joel Berrier, Daniel Kennefick, in "Constraining dark matter halo profiles and galaxy formation models using spiral arm morphology. II. Dark and stellar mass concentrations for 13 nearby face-on galaxies" (September 23, 2014). Most notably, the abstract of the paper reports that: "we show that there appears to be a trend (albeit a weak correlation) between spiral arm pitch angle and halo concentration. We discuss implications for the suggested link between supermassive black hole (SMBH) mass and dark halo concentration, using pitch angle as a proxy for SMBH mass." These trends are a fit for those suggested by Deur in his graviton self-interaction model (i.e. a relationship between the magnitude of dark matter effects and overall mass and deviation from spherical symmetry).
Meanwhile, Gerasimos Rigopoulos, in "A Relativistic view on large scale N-body simulations" (September 23, 2014), notes that while Newtonian N-body simulations approximate the general relativistic behavior accurately at the first order, that there are material second order non-linear effects in general relativity that are not captured by such simulations making them inappropriate to use, particularly in very large simulations, without modification.
Dark Matter Creation
One of the strongest warm dark matter candidates is suggested by X-ray observations from galaxy clusters.
The recent observation of an X-ray line at an energy of 3.5 keV mainly from galaxy clusters has generated a buzz in the Dark Matter community. If confirmed, this signal could stem from a decaying sterile neutrino of a mass of 7.1 keV. Such a particle could make up all the Dark Matter, but it is not clear how it was produced in the early Universe.
In this paper we show that it is possible to discriminate between different production mechanisms with present-day astronomical data. The most stringent constraint comes from the Lyman-α forest and seems to disfavor all but one of the main production mechanisms proposed in the literature, which is the production via decay of heavy scalar singlets. Pinning down the production mechanism will help to decide whether the X-ray signal indeed comprises an indirect detection of Dark Matter.- Alexander Merle and Aurel Schneider entitled "Production of Sterile Neutrino Dark Matter and the 3.5 keV line" (September 22, 2014).
The surprise ending to this paper is that the only means of production consistent with the Lyman alpha forest produces unusually slow moving (i.e. "cold") dark matter particles that have the same "small scale" problems as cold dark matter. Despite its low mass, particles produced in this fashion would be cold dark matter, rather than the expected warm dark matter, which is disfavored by astronomy observations such as satellite galaxy abundance.
Thus, the bottom line of the paper is really to disfavor the 3.5 keV X-ray line as a true signal of dark matter decay, because that interpretation, taken to its logical conclusion, produces contradictory data.
BICEP-2 Questioned Again
Finally, a new analysis of the BICEP-2 data in light of Planck dust polarization data adds to the chorus of doubt about the validity of the signal that the experiment claims it observed of primordial gravitational tensor waves. The paper is Marina Cortês, Andrew R Liddle, and David Parkinson, "Tensors, BICEP2, prior dependence, and dust" (September 23, 2014). They state:
When foregrounds are accounted for, the BICEP2 results no longer require non-standard inflationary parameter regions. We present limits on primordial AT and nT, adopting foreground scenarios put forward by Mortonson & Seljak and motivated by Planck 353 GHz observations, and assess what dust contribution leaves a detectable cosmological signal. We find that if there is sufficient dust for the signal to be compatible with standard inflation, then the primordial signal is too weak to be robustly detected by BICEP2 if Planck+WMAP upper limits from temperature and E-mode polarization are correct.Planck dust and polarization data has been trickling out over the last few months, and this paper is probably still not the definitive one. But, the prospects for the BICEP2 result holding up don't look particularly good.
Thursday, September 18, 2014
Our Tribe
Humans are part of a subfamily called Homininae made up of chimpanzees, gorillas (of which there are two extant species that share a genus, and one extinct species in a separate genus), humans, and a number of extinct species which are or are closely related to human ancestor species.
At least until recently, the next level of classification called a "tribe" was called Hominini which included two extant sub-tribes (one made up of chimpanzees and one made up of humans and extinct species ancestral to them), as well two other extinct species Sahelanthropus tchadensis and Orrorin tugenensis, who appear to be more closely related to humans and chimpanzees than they are to gorillas , but who cannot clearly be classified as part of either a chimpanzee clade, or a clade that includes humans.
Apparently, the modern trend is to define this "tribe" in a way that excludes chimpanzees (all of genus Pan), but includes Sahelanthropus tchadensis and Orrorin tugenensis, as well as subtribe Hominina which includes extinct genus Ardipithecus, extinct genus Kenyanthropus, extinct genus Praeanthropus, extinct genus Australopithecus, extinct genus Paranthropus, and the extant and extinct species of the genus Homo that includes modern humans.
There are arguably as many as 26 formally classified extinct species in seven genuses that are human ancestors or closely related to human ancestors, in addition to arguably three archaic subspecies of the species Homo Sapiens that are extinct in addition to extant modern humans. But, since many of these species classifications are based upon incomplete skeletal remains from a single location, or from genetic traces without enough skeletal material to meaningfully describe them, these classifications are at best contingent and subject to reassessment as more data becomes available. The map below from the Wikipedia article on Ardipithecus illustrates the situation:
.svg)
[Proconsul in the map above is the 24 million year old ancestor of gibbons and great apes including chimpanzees, gorillas and modern humans. Aegyptopithecus is a 34 million year old ancestor of monkeys and great apes alike. The other five species on the map post-date the divergence of chimpanzees and modern human ancestors, but predate Homo Erectus.]
The prevailing view these days is to lump Kenyanthropus and Praenthropus into Australopithecus. There is currently division between whether Paranthropus, which are relatively recent fossils with somewhat less archaic features in some respects should be included in Australopithecus as well. The six million year old Orrorin is arguably more human-like than Australopithecus (e.g. Lucy) despite being about 3 million years earlier. Sahelanthropus tchadensis, which is about 7 million years old, has been classified variously as a common chimpanzee-human ancestor, as part of the genus Ardipithecus (which is about 4.4 million years old), and as the ancestor not of humans but of gorillas. The oldest fossil representatives of the genus Homo (i.e. Homo habilis) are at most 2.33 million years old.
However you choose to classify the various species, there is little debate that animals in the genus Pan, made up of one species with four subspecies of common chimpanzees (Pan troglodytes of the Western, Nigeria-Cameroon, Central and Eastern varieties, in geographic order, with a substantial gap between Western chimpanzees and the continuum of the other three subspecies, with some zoologists preferring to split Eastern chimpanzees into separate Northern and Southern subspecies rather than lumping them into a single subspecies), and one species of bonobos (Pan paniscus) aka pygmy chimpanzees, are more closely related to modern humans than any other species of animals that still exist today. There are roughly 170,000-300,000 common chimpanzees and 30,000-50,000 bonobos alive today. Common chimpanzees have 23 chromosomes, bonobos have 24 chromosomes and modern humans have 26 chromosomes, but the chromosome divisions are such that particular genes in modern humans usually have corresponding genes, sometimes on a different chromosome, in chimpanzees and bonobos.
The split between ancestors of modern humans and the genus Pan is estimated to date to four to six million years ago, which is also around the time that a lot of "missing link" species that are probably ancestors of modern humans or related to ancestors of modern humans more closely than to chimpanzees, even if they are not directly ancestral to modern humans, start to appear in the fossil record. There is evidence, albeit weak, to suggest that the split probably took place near the Eastern edge of the modern range of chimpanzees in the vicinity of the East African Rift Valleys, which is the only place where current fossil evidence of archaic human ancestors and chimpanzees overlaps. But, this could be due to the poor conditions for fossil preservation of remains that can be discovered by archaeologists today in jungles, and a lack of exploration in other parts of Africa due to war and poverty.
The split between Pan troglodyes and Pan paniscus is estimated to date to about a million years ago, although circumstantial evidence suggests that 1.5-2 million years ago (as a result of the formation of the Congo River) may been a more accurate date. Chimpanzees live North of the Congo River, while Bonobos live South of the Congo River. Thus, chimpanzees and bonobos are modestly more closely related than humans are to Homo Erectus (which emerged as a species about two million years ago), but less closely related than humans are to Neanderthals (which emerged as a species perhaps 500,000 years ago). The species Homo Sapien came into being around 250,000 years ago or so, humans left Africa around 125,000 to 100,000 years ago, and non-African humans began to differentiate into distinct sub-populations around 75,000 years ago. Neanderthals went extinct around 29,000 years ago, and probably at least one species of archaic hominins in Asia, and another in Africa probably walked the Earth as recently as 12,000 years ago.
There is a slim possibility that there may be a few dozens archaic hominins still alive in some remote corner of the early such as deep in some Indonesian jungle, or remote part of the Himalayas, although xenobiologists who have looked for them have so far come up empty, and any such species would have to be at a minimum a moribund relict population, even if they are not entirely extinct right now.
Chimpanzees and bonobos are generally viewed as more closely related to each other than they are to modern humans, although neither of the two species is decisively more closely related to modern humans than the other.
While chimpanzees and bonobos are close genetic relatives, in an evolutionary sense, however, they are behaviorally very different. Chimpanzees are not only bigger on average than bonobos, but also have much greater size differences between the larger males and the smaller females. They also murder each other (usually members of other bands of chimpanzees) on a fairly regular basis. In contrast, bonobos are the epitome of the slogan "make love, not war".
Bonobos are exceedingly promiscuous by the standard of humans or other great Apes. They routinely engage in sex for pleasure rather than reproduction in every way that a porn star could imagine, are polyamorous, and frequently bisexual in the non-reproductive sexual activity. They are at least three to twenty-five times less likely to murder each other as chimpanzees, are smaller than chimpanzees, and have far less size disparity between males and females. The bonobo murder rate is of the same order of magnitude as the murder rate in contemporary human communities, not more than 20 per 100,000 individual per year, while the chimpanzee murder rate is at least 73 per 100,000 individuals per year.
A new study in the journal Nature, substantiates these stereotypes and also shows similarities between the parties of murder in chimpanzees and those of gang murders among humans today. As the abstract to the article explains:
Humans are behaviorally and physically, intermediate between are Pan troglodytes and Pan paniscus evolutionary relatives. Human males are bigger than human females, but not as excessively as Pan troglodytes or as slightly as Pan paniscus. We are less promiscuous than bonobos, but more promiscuous and sexual and varied in our non-reproductive use of sexuality than chimpanzees. We are less violent and murderous than chimpanzees are towards each other, but when we do murder, we often fall into patterns similar to that of chimpanzees. We show the same kind of xenophobia and fear of outsiders as chimpanzees do, but define our communities much more broadly than any of our primate evolutionary relatives.
All of species in subtribe Hominina, Sahelanthropus tchadensis, Orrorin tugenensis, Pan troglodytes and Pan paniscus share a common ancestor who was probably also intermediate behaviorally between modern chimpanzees and modern bonobos.
At least until recently, the next level of classification called a "tribe" was called Hominini which included two extant sub-tribes (one made up of chimpanzees and one made up of humans and extinct species ancestral to them), as well two other extinct species Sahelanthropus tchadensis and Orrorin tugenensis, who appear to be more closely related to humans and chimpanzees than they are to gorillas , but who cannot clearly be classified as part of either a chimpanzee clade, or a clade that includes humans.
Apparently, the modern trend is to define this "tribe" in a way that excludes chimpanzees (all of genus Pan), but includes Sahelanthropus tchadensis and Orrorin tugenensis, as well as subtribe Hominina which includes extinct genus Ardipithecus, extinct genus Kenyanthropus, extinct genus Praeanthropus, extinct genus Australopithecus, extinct genus Paranthropus, and the extant and extinct species of the genus Homo that includes modern humans.
There are arguably as many as 26 formally classified extinct species in seven genuses that are human ancestors or closely related to human ancestors, in addition to arguably three archaic subspecies of the species Homo Sapiens that are extinct in addition to extant modern humans. But, since many of these species classifications are based upon incomplete skeletal remains from a single location, or from genetic traces without enough skeletal material to meaningfully describe them, these classifications are at best contingent and subject to reassessment as more data becomes available. The map below from the Wikipedia article on Ardipithecus illustrates the situation:
.svg)
[Proconsul in the map above is the 24 million year old ancestor of gibbons and great apes including chimpanzees, gorillas and modern humans. Aegyptopithecus is a 34 million year old ancestor of monkeys and great apes alike. The other five species on the map post-date the divergence of chimpanzees and modern human ancestors, but predate Homo Erectus.]
The prevailing view these days is to lump Kenyanthropus and Praenthropus into Australopithecus. There is currently division between whether Paranthropus, which are relatively recent fossils with somewhat less archaic features in some respects should be included in Australopithecus as well. The six million year old Orrorin is arguably more human-like than Australopithecus (e.g. Lucy) despite being about 3 million years earlier. Sahelanthropus tchadensis, which is about 7 million years old, has been classified variously as a common chimpanzee-human ancestor, as part of the genus Ardipithecus (which is about 4.4 million years old), and as the ancestor not of humans but of gorillas. The oldest fossil representatives of the genus Homo (i.e. Homo habilis) are at most 2.33 million years old.
However you choose to classify the various species, there is little debate that animals in the genus Pan, made up of one species with four subspecies of common chimpanzees (Pan troglodytes of the Western, Nigeria-Cameroon, Central and Eastern varieties, in geographic order, with a substantial gap between Western chimpanzees and the continuum of the other three subspecies, with some zoologists preferring to split Eastern chimpanzees into separate Northern and Southern subspecies rather than lumping them into a single subspecies), and one species of bonobos (Pan paniscus) aka pygmy chimpanzees, are more closely related to modern humans than any other species of animals that still exist today. There are roughly 170,000-300,000 common chimpanzees and 30,000-50,000 bonobos alive today. Common chimpanzees have 23 chromosomes, bonobos have 24 chromosomes and modern humans have 26 chromosomes, but the chromosome divisions are such that particular genes in modern humans usually have corresponding genes, sometimes on a different chromosome, in chimpanzees and bonobos.
The split between ancestors of modern humans and the genus Pan is estimated to date to four to six million years ago, which is also around the time that a lot of "missing link" species that are probably ancestors of modern humans or related to ancestors of modern humans more closely than to chimpanzees, even if they are not directly ancestral to modern humans, start to appear in the fossil record. There is evidence, albeit weak, to suggest that the split probably took place near the Eastern edge of the modern range of chimpanzees in the vicinity of the East African Rift Valleys, which is the only place where current fossil evidence of archaic human ancestors and chimpanzees overlaps. But, this could be due to the poor conditions for fossil preservation of remains that can be discovered by archaeologists today in jungles, and a lack of exploration in other parts of Africa due to war and poverty.
The split between Pan troglodyes and Pan paniscus is estimated to date to about a million years ago, although circumstantial evidence suggests that 1.5-2 million years ago (as a result of the formation of the Congo River) may been a more accurate date. Chimpanzees live North of the Congo River, while Bonobos live South of the Congo River. Thus, chimpanzees and bonobos are modestly more closely related than humans are to Homo Erectus (which emerged as a species about two million years ago), but less closely related than humans are to Neanderthals (which emerged as a species perhaps 500,000 years ago). The species Homo Sapien came into being around 250,000 years ago or so, humans left Africa around 125,000 to 100,000 years ago, and non-African humans began to differentiate into distinct sub-populations around 75,000 years ago. Neanderthals went extinct around 29,000 years ago, and probably at least one species of archaic hominins in Asia, and another in Africa probably walked the Earth as recently as 12,000 years ago.
There is a slim possibility that there may be a few dozens archaic hominins still alive in some remote corner of the early such as deep in some Indonesian jungle, or remote part of the Himalayas, although xenobiologists who have looked for them have so far come up empty, and any such species would have to be at a minimum a moribund relict population, even if they are not entirely extinct right now.
Chimpanzees and bonobos are generally viewed as more closely related to each other than they are to modern humans, although neither of the two species is decisively more closely related to modern humans than the other.
While chimpanzees and bonobos are close genetic relatives, in an evolutionary sense, however, they are behaviorally very different. Chimpanzees are not only bigger on average than bonobos, but also have much greater size differences between the larger males and the smaller females. They also murder each other (usually members of other bands of chimpanzees) on a fairly regular basis. In contrast, bonobos are the epitome of the slogan "make love, not war".
Bonobos are exceedingly promiscuous by the standard of humans or other great Apes. They routinely engage in sex for pleasure rather than reproduction in every way that a porn star could imagine, are polyamorous, and frequently bisexual in the non-reproductive sexual activity. They are at least three to twenty-five times less likely to murder each other as chimpanzees, are smaller than chimpanzees, and have far less size disparity between males and females. The bonobo murder rate is of the same order of magnitude as the murder rate in contemporary human communities, not more than 20 per 100,000 individual per year, while the chimpanzee murder rate is at least 73 per 100,000 individuals per year.
A new study in the journal Nature, substantiates these stereotypes and also shows similarities between the parties of murder in chimpanzees and those of gang murders among humans today. As the abstract to the article explains:
Observations of chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) provide valuable comparative data for understanding the significance of conspecific killing. . . . we compiled information from 18 chimpanzee communities and 4 bonobo communities studied over five decades. Our data include 152 killings (n = 58 observed, 41 inferred, and 53 suspected killings) by chimpanzees in 15 communities and one suspected killing by bonobos. We found that males were the most frequent attackers (92% of participants) and victims (73%); most killings (66%) involved intercommunity attacks; and attackers greatly outnumbered their victims (median 8:1 ratio). Variation in killing rates was unrelated to measures of human impacts.Thus, murders are much more common in chimpanzee communities (with 99 confirmed and 53 suspected killings in fifty years in eighteen communities studied) than in bonobo communities (with no confirmed killings and one suspected killing in fifty years in four communities). The percentage of chimpanzee murder suspects who were male is almost identical to that of human murder suspects. And, the pattern of killing predominantly other males in neighboring communities in groups, is very similar to the pattern of gang killed in American ghettos during high crime periods.
Humans are behaviorally and physically, intermediate between are Pan troglodytes and Pan paniscus evolutionary relatives. Human males are bigger than human females, but not as excessively as Pan troglodytes or as slightly as Pan paniscus. We are less promiscuous than bonobos, but more promiscuous and sexual and varied in our non-reproductive use of sexuality than chimpanzees. We are less violent and murderous than chimpanzees are towards each other, but when we do murder, we often fall into patterns similar to that of chimpanzees. We show the same kind of xenophobia and fear of outsiders as chimpanzees do, but define our communities much more broadly than any of our primate evolutionary relatives.
All of species in subtribe Hominina, Sahelanthropus tchadensis, Orrorin tugenensis, Pan troglodytes and Pan paniscus share a common ancestor who was probably also intermediate behaviorally between modern chimpanzees and modern bonobos.
Wednesday, September 17, 2014
Two Higgs Doublet Models Almost Completely Ruled Out
Only an extreme tiny parameter space for theories with five Higgs bosons (such as minimal and next to minimal supersymmetric models) rather than the one Higgs boson of the Standard Model remains open, and only in one specific subset of such models (type X - "lepton specific" models), for a very narrow range of parameters in that type of model.
Specifically, the parameter space requires that the charged Higgs bosons have masses of less than 200 GeV that are almost degenerate with the SM Higgs boson at 125.5 GeV, have a large "tan beta", a precise difference between the parameter angle beta and another parameter angle alpha equal to about pi/2 (i.e. 90 degrees), and a fairly light pseudoscalar Higgs boson.
The remaining two Higgs Doublet parameter space can probably be ruled out (or confirmed) in the second LHC run.
This is a really blow to SUSY theories and a fortiori, to String Theory, as well as the larger and more generic class of two Higgs Doublet models.
If two Higgs doublet models are ruled out, then any SUSY model must have at least three Higgs doublets (i.e. nine Higgs bosons) with nine of them at very high masses.
Specifically, the parameter space requires that the charged Higgs bosons have masses of less than 200 GeV that are almost degenerate with the SM Higgs boson at 125.5 GeV, have a large "tan beta", a precise difference between the parameter angle beta and another parameter angle alpha equal to about pi/2 (i.e. 90 degrees), and a fairly light pseudoscalar Higgs boson.
The remaining two Higgs Doublet parameter space can probably be ruled out (or confirmed) in the second LHC run.
This is a really blow to SUSY theories and a fortiori, to String Theory, as well as the larger and more generic class of two Higgs Doublet models.
If two Higgs doublet models are ruled out, then any SUSY model must have at least three Higgs doublets (i.e. nine Higgs bosons) with nine of them at very high masses.
Tuesday, September 16, 2014
MOND Still Works Within Its Domain of Applicability
MOND is a theory developed by Israeli scientist Mordeci Milgrom about thirty years ago, that describes galaxy level phenomena usually attributed to dark matter in the form of an equation that modifies Newton's law of gravity in weak gravitational fields beyond an acceleration value that is constant in the theory.
MOND does not have an underlying theoretical basis, although it suggests possible ones. But, in its domain of applicability, at the level of systems the size of single galaxies or smaller, it explains observed phenomena parsimoniously with just one experimentally measured parameter and one formula.
MOND is not an accurate law of nature in all circumstances. It substantially underestimates dark matter phenomena in systems the size of galactic clusters or larger, and also has problems in systems such as the Bullet Cluster collision. It is also not relativistic, although a generalization of MOND called TeVeS has been developed by one of Mr. Milgrom's colleagues. But, in its domain of applicability describing kinematics in systems the size of single galaxies or smaller, general relativity and Newtonian gravity are usually assumed to be almost indistinguishable.
One of the things that makes MOND particularly notable is that it has made numerous predictions before evidence was available and without modification regarding dark matter phenomena in its domain of applicability that have later been established empirically. It has a better track record in that regard that dark matter theory.
Thus, even if dark matter effects are due to particles rather than a modification of the laws of gravity, and even if there is something wrong with MOND's modified gravity formula, it has empirically been demonstrated to be a succinct and accurate description of reality in its domain of applicability.
In other words, whatever the true mechanism of dark matter phenomena is, whether it is a "dark sector" of particles, or a modification of the laws of gravity, or a previously not understood non-linear implication of general relativity, the correct answer must reduce to something equivalent to MOND in its domain of applicability in practice.
The latest paper on the subject, demonstrates that MOND again makes accurate predictions about the frequency with which bulges are observed in spiral galaxies, which is contrary to the predictions made by standard cold dark matter theories. The paper also makes further predictions regarding these bulges which can be confirmed in future research.
MOND does not have an underlying theoretical basis, although it suggests possible ones. But, in its domain of applicability, at the level of systems the size of single galaxies or smaller, it explains observed phenomena parsimoniously with just one experimentally measured parameter and one formula.
MOND is not an accurate law of nature in all circumstances. It substantially underestimates dark matter phenomena in systems the size of galactic clusters or larger, and also has problems in systems such as the Bullet Cluster collision. It is also not relativistic, although a generalization of MOND called TeVeS has been developed by one of Mr. Milgrom's colleagues. But, in its domain of applicability describing kinematics in systems the size of single galaxies or smaller, general relativity and Newtonian gravity are usually assumed to be almost indistinguishable.
One of the things that makes MOND particularly notable is that it has made numerous predictions before evidence was available and without modification regarding dark matter phenomena in its domain of applicability that have later been established empirically. It has a better track record in that regard that dark matter theory.
Thus, even if dark matter effects are due to particles rather than a modification of the laws of gravity, and even if there is something wrong with MOND's modified gravity formula, it has empirically been demonstrated to be a succinct and accurate description of reality in its domain of applicability.
In other words, whatever the true mechanism of dark matter phenomena is, whether it is a "dark sector" of particles, or a modification of the laws of gravity, or a previously not understood non-linear implication of general relativity, the correct answer must reduce to something equivalent to MOND in its domain of applicability in practice.
The latest paper on the subject, demonstrates that MOND again makes accurate predictions about the frequency with which bulges are observed in spiral galaxies, which is contrary to the predictions made by standard cold dark matter theories. The paper also makes further predictions regarding these bulges which can be confirmed in future research.
Measuring Nothing
A great deal of modern astronomy and cosmology is based upon experimental observations of clusters of luminous matter.
Typically, one devised a model of how one expects the structure of the universe to develop over time, implements it on a Monte Carlo basis thousands of time, evaluates the results statistically, and compares them to observations. Models that rarely produce results that are statistically similar to our universe are ruled out. Models that often produce results that are statistically similar to our universe are considered to be consistent with the empirical evidence.
But, statistically identifying clusters of luminous matter in astronomy observations is tricky business. A small number of individual stars or galaxies with peculiar velocities (a vector quantity that measures both speed and direction), or a subtle misjudgment of red shift or angle in an observed luminous object, can add a great deal of statistical noise to an effort to accurately identify clusters of stars. These systemic uncertainties in the observations of the real world universe can make it hard to rule out any models, since so many possibilities are consistent with observation to within reasonable margins of error.
A couple of papers over the last few days (here and here) have used a more statistically robust way of measuring many of the phenomena normally studied using analysis of clusters of stars and galaxies. Rather than measuring clusters of stars, the technique measures the location and extent of clusters of cosmic voids - the space between luminous objects in space.
In other words, the astronomers are literally measuring "nothing", rather than measuring the "stuff" itself.
Cosmic voids can be measured using essentially the same data points as traditional cluster analysis, but this approach to the analysis is more statistically robust. Since the "thing" observed in part of a cosmic void is the complete absence of luminous matter, uncertainties regarding its properties and red shift are gone. And, since most of space is empty, cosmic voids are more spatially expansive than stars or galaxies, so one does not have to fix their location so precisely to accurately capture their statistical distribution.
Yet, the clustering of cosmic voids is almost as useful as the clustering of luminous matter in empirically testing questions about the large scale structure of the universe, such as cosmological homogeneity in the universe that has been analyzed traditionally in the past, or traces of "inflation" in the early moments of the universe revealed by "clustering fossils." Any computer model of how large scale structure arises can be quantified in terms of its cosmic void structure just as easily as it can be quantified in terms of its clusters of luminous matter, and these predictions can then be compared to empirical data about cosmic voids which is more statistically robust.
Kudos to the authors for coming up with this clever and non-intuitive means of data analysis.
References:
* Teeraparb Chantavat, Utane Sawangwit, P. M. Sutter, Benjamin D. Wandelt, "Cosmological Parameter Constraints from CMB Lensing with Cosmic Voids" (September 11, 2014).
* Kwan Chuen Chan, Nico Hamaus, Vincent Desjacques, "Large-Scale Clustering of Cosmic Voids" (September 12, 2014)
Typically, one devised a model of how one expects the structure of the universe to develop over time, implements it on a Monte Carlo basis thousands of time, evaluates the results statistically, and compares them to observations. Models that rarely produce results that are statistically similar to our universe are ruled out. Models that often produce results that are statistically similar to our universe are considered to be consistent with the empirical evidence.
But, statistically identifying clusters of luminous matter in astronomy observations is tricky business. A small number of individual stars or galaxies with peculiar velocities (a vector quantity that measures both speed and direction), or a subtle misjudgment of red shift or angle in an observed luminous object, can add a great deal of statistical noise to an effort to accurately identify clusters of stars. These systemic uncertainties in the observations of the real world universe can make it hard to rule out any models, since so many possibilities are consistent with observation to within reasonable margins of error.
A couple of papers over the last few days (here and here) have used a more statistically robust way of measuring many of the phenomena normally studied using analysis of clusters of stars and galaxies. Rather than measuring clusters of stars, the technique measures the location and extent of clusters of cosmic voids - the space between luminous objects in space.
In other words, the astronomers are literally measuring "nothing", rather than measuring the "stuff" itself.
Cosmic voids can be measured using essentially the same data points as traditional cluster analysis, but this approach to the analysis is more statistically robust. Since the "thing" observed in part of a cosmic void is the complete absence of luminous matter, uncertainties regarding its properties and red shift are gone. And, since most of space is empty, cosmic voids are more spatially expansive than stars or galaxies, so one does not have to fix their location so precisely to accurately capture their statistical distribution.
Yet, the clustering of cosmic voids is almost as useful as the clustering of luminous matter in empirically testing questions about the large scale structure of the universe, such as cosmological homogeneity in the universe that has been analyzed traditionally in the past, or traces of "inflation" in the early moments of the universe revealed by "clustering fossils." Any computer model of how large scale structure arises can be quantified in terms of its cosmic void structure just as easily as it can be quantified in terms of its clusters of luminous matter, and these predictions can then be compared to empirical data about cosmic voids which is more statistically robust.
Kudos to the authors for coming up with this clever and non-intuitive means of data analysis.
References:
* Teeraparb Chantavat, Utane Sawangwit, P. M. Sutter, Benjamin D. Wandelt, "Cosmological Parameter Constraints from CMB Lensing with Cosmic Voids" (September 11, 2014).
* Kwan Chuen Chan, Nico Hamaus, Vincent Desjacques, "Large-Scale Clustering of Cosmic Voids" (September 12, 2014)
Wednesday, September 10, 2014
More Higgs Boson Measurements From CMS (with corrections and updates 091114)
The CMS experiment at the Large Hadron Collider (LHC) has released its latest sets of experimental Higgs boson measurements today, from H-->ZZ-->four lepton decay channels.
The key points:
* The Higgs boson discovery is confirmed with a 6.8 sigma significance.
* The latest measurement by CMS of the Higgs boson mass in this channel is 125.6 GeV +/- 0.4 +/- 0.2.
Before this preprint was released the most recent CMS four lepton mass measurement was 125.8 +/- 0.5 +/- 0.2. The new CMS four lepton mass estimate is 0.2 GeV lighter and is 8% more precise.
Thus, the relevant Higgs boson mass data points are now:
* The ATLAS diphoton mass is 125.98 +/- 0.42 +/- 0.28 (June 15, 2014)
* The ATLAS four lepton mass is 124.51 +0.52 +/- 0.06 (June 15, 2014)
* The ATLAS combined mass value is 125.36 +/- 0.37 +/- 0.18 (June 15, 2014)
* The CMS diphoton number is 124.7 +/- 0.31 +/- 0.15 (July 2, 2014)
* The CMS four lepton mass is 125.6 +/- 0.4 +/- 0.2 (September 10, 2014). This is substantially similar to a June 10, 2014 release from CMS updating one of its December 2013 papers.
* The combined CMS number is 125.03 +0.26/-0.25+0.13/-0.15 (July 3, 2014).
The naive global average Higgs boson mass is now about 125.15 GeV. The range of value for measurements by the same experiments and by different experiments of the same decay channel, however, cast doubt on the accuracy of the error bars claimed.
* Another Standard Mode-like Higgs boson was excluded with 95% confidence in the mass range from 129.5-832.0 GeV.
* The strength of the ZZ decay channel of the Higgs boson relative to the Standard Model expectation is mu=0.93 +0.26/-0.23 +0.13/-0.09. This is closer to the expected value of 1.0 if the Standard Model is correct, than the previous measurement, and is less than a quarter of a Standard Deviation from the expected value. The PDG value of mu in the ZZ channel was 0.80 +0.35/-0.28 at CMS and was 1.2 +/- 0.6 at ATLAS.
* The Higgs boson width is less than 33 MeV at the 95% confidence level (the SM expectation is 4.15 MeV). A limit of about 17 MeV has already been established by other means, but this is still a significant improvement at measuring this property of the Higgs boson in this decay channel alone.
* CMS confirms the results of other experiments in ruling out non-Standard Model spin (actually total angular momentum J) or parity (the SM Higgs is + aka "even").
The key points:
* The Higgs boson discovery is confirmed with a 6.8 sigma significance.
* The latest measurement by CMS of the Higgs boson mass in this channel is 125.6 GeV +/- 0.4 +/- 0.2.
Before this preprint was released the most recent CMS four lepton mass measurement was 125.8 +/- 0.5 +/- 0.2. The new CMS four lepton mass estimate is 0.2 GeV lighter and is 8% more precise.
Thus, the relevant Higgs boson mass data points are now:
* The ATLAS diphoton mass is 125.98 +/- 0.42 +/- 0.28 (June 15, 2014)
* The ATLAS four lepton mass is 124.51 +0.52 +/- 0.06 (June 15, 2014)
* The ATLAS combined mass value is 125.36 +/- 0.37 +/- 0.18 (June 15, 2014)
* The CMS diphoton number is 124.7 +/- 0.31 +/- 0.15 (July 2, 2014)
* The CMS four lepton mass is 125.6 +/- 0.4 +/- 0.2 (September 10, 2014). This is substantially similar to a June 10, 2014 release from CMS updating one of its December 2013 papers.
* The combined CMS number is 125.03 +0.26/-0.25+0.13/-0.15 (July 3, 2014).
The naive global average Higgs boson mass is now about 125.15 GeV. The range of value for measurements by the same experiments and by different experiments of the same decay channel, however, cast doubt on the accuracy of the error bars claimed.
* Another Standard Mode-like Higgs boson was excluded with 95% confidence in the mass range from 129.5-832.0 GeV.
* The strength of the ZZ decay channel of the Higgs boson relative to the Standard Model expectation is mu=0.93 +0.26/-0.23 +0.13/-0.09. This is closer to the expected value of 1.0 if the Standard Model is correct, than the previous measurement, and is less than a quarter of a Standard Deviation from the expected value. The PDG value of mu in the ZZ channel was 0.80 +0.35/-0.28 at CMS and was 1.2 +/- 0.6 at ATLAS.
* The Higgs boson width is less than 33 MeV at the 95% confidence level (the SM expectation is 4.15 MeV). A limit of about 17 MeV has already been established by other means, but this is still a significant improvement at measuring this property of the Higgs boson in this decay channel alone.
* CMS confirms the results of other experiments in ruling out non-Standard Model spin (actually total angular momentum J) or parity (the SM Higgs is + aka "even").
Tuesday, September 9, 2014
Putting Together The Pieces In The New World And Europe
A great deal of effort in archaeology, population genetics, historical linguistics, plant genetics, climate history, ancient history, and anthropology in the past couple of decades, and with some level of scientific integrity and vigor for the last century and a half, has been devoted to assembling pieces of one big puzzle that can be solved only once . . . understanding human prehistory.
New World Prehistory
Arctic Genetic Prehistory
Some of the most definitive answers about the prehistory of the Americas came in an analysis of ancient DNA and modern population genetics released a couple of weeks ago.[1] This study established that:
1. The Saqqaq and Dorest Paleo-Eskimo populations were a single, closely genetically related migration wave, that arrived in Arctic North America around 3500 BCE and persisted until about 500 CE, despite the marked break in archaeological culture between the sequential populations. These Paleo-Eskimos had surprisingly little genetic admixture with either pre-existing Native American populations, or with the proto-Inuits who ultimately replaced them in the Arctic - consistent with Inuit legends describing a distinct arctic people who kept themselves separate from other peoples
2. The 6th to 7th century CE Berginian Birnirk culture (in turn derived from Siberian populations) is the source of the proto-Inuit Thule people, who were the last substantial and sustained pre-Columbian peoples to migrate to the Americas.
3. "Although we cannot preclude later gene flow between the Dorset and the Thule (that is, subsequent to the more ancient gene flow that occurred at least 4000 years ago), the contrasting genetic and cultural affinities of the Sadlermiut individuals present a conundrum. This culture that went extinct in 1903 CE from European disease has long been considered Thule-acculturated Dorset people, likely due to intermarriage; however, genetic evidence from this study suggests that they were Thule people who had somehow acquired Dorset stone technology."
The Na-Dene people
The Na-Dene people (aka Athapaskans) do not have significant Paleo-Eskimo admixture.[1] This can be added to some other notable data points in the existing literature about the Na-Dene:
* Genetic and linguistic evidence establish that the Na-Dene people are distinct not only from Paleo-Eskimos and the Inuit, but also from other Native Americans. While the Na-Dene are heavily admixed with pre-existing Native American populations, there are genetic indicators of a wave of Na-Dene migration long after the original peopling of the Americas by modern humans ca. 15,000-18,000 years ago. About 10% of Na-Dene ancestry is distinct from the initial founding population of the Americas.[2] The Na-Dene, like Inuits, have Y-DNA haplogroups that are specific to them and of more recent origin that the founding Y-DNA haplogroups of the Americas.[3]
* Linguistic evidence establishes that the Na-Dene people's expansion is North America originated in Western Alaska and moved east from there to the rest of Alaska, Western Canada, and the Pacific Northwest.
* The earliest archaeological evidence of Na-Dene people in Alaska comes from the general vicinity of Wrangell-St. Elias National Park in Southern Alaska around 1500 BCE although arguably they were present in the Southwestern Yukon in Canada as early as 2500 BCE.
* The Na-Dene languages are related to the Yenesian languages of the Ket people of Siberia, a Paleo-Siberian population that was exiled from general vicinity of the Altai Mountain region of Southern Siberia to Siberia's Yenesian River area around 0 CE, according to the oral histories of the Ket people. The strength of the linguistic connection is consistent with a divergence of the two language families from a common origin around 3500-4000 years ago, a similar time depth, for example, to the division between Latin and Gaelic in the Indo-European language family.
* Substantial admixture with local populations by both the Ket people and that Na-Dene people, however, has obscured any common genetic linkages of these peoples, which would already have been difficult to detect using the crude 1993 genetic tests of the Ket people applied to a small sample that was used to make the comparison.
* The Na-Dene people migrated in two parallel waves from different parts of Western Canada to the American Southwest around 1000 CE. Their descendants are the Apache and Navajo tribes.
Other New World Contacts
* Around 1000 CE, Lief Erickson led a small population of Vikings to a short lived agricultural settlement called Vinland in maritime Canada. Recent discoveries announced in National Geographic in November of 2012 established that there were trade relations between the Vikings and indigeneous Arctic people at around the same time at the Northern tip of Canada's Baffin Island.
* From around 900 CE to 1100 CE, the "people who lived more than 1,000 years ago in what today is the Lambayeque region, about 800 kilometers (500 miles) north of Lima, had genetic links to the contemporaneous populations of Ecuador, Colombia, Siberia, Taiwan and to the Ainu people of northern Japan." These people were practitioners of the Middle Sican culture, a cultural renaissance in the region marked by veneration of "Sican diety" and "Sican lord" with vaguely Asian eyes in material cultural items including pottery and metalwork, who reputedly came to them from across the ocean via a balsa wood raft. (Earlier ancient mtDNA work here and here). A few hundred years later, however, the Sican diety cult abated.
The First Americans
* The remaining peoples of the Americas, with a quite small founding population, crossed the Berginian land bridge from Northeast Asia, were bottled up there cutoff by cold and glaciers from both Asia and the rest of North America, and then migrated to the rest of the Americas once the glaciers subsided enough to allow them to pass to the rest of the continent.[4] One group took a Pacific coastal route that reached South America within about a thousand years.[4] The other made their way to eastern North America and moved Westward starting around the time of the emergence of the Clovis culture.
Some investigators, such as those conducting a 2013 mtDNA analysis have argued that the Indigeneous peoples of South America have only a subset of the first Americans whose full range of Y-DNA and mtDNA diversity is preserved only in North America and is attributable to a wave of inland migration limited to North America.[5] In particular, they see mtDNA X2a and C4c as markers of this migration.[5] This areal distinction predates and is not difference between Na-Dene and non-Na-Dene people, and instead derived from local Na-Dene admixture with other Native American populations.[5] High coverage autosomal data in a 2013 study do show some North-South cline in the Americas, but not a lot of distinct population structure.[7]
In contrast, a 2007 paper argued instead that there was no population genetic structure in the founding population of the Americas, at least at the major mtDNA clade level. [4] A 2004 Y-DNA analysis came to a similar conclusion.[6] It is not clear if apparent differences in diversity are a serial founder effect, or if the greater genetic diversity in North American Native Americans reflects a Beringian population that he some population structure consisting of at least two distinct peoples when the path from Beringia to North America opened up, or if apparent structure is simply illusory.
* The first Americans brought dogs, but not horses, and were hunter-gatherers. Mega-fauna extinction across the Americas followed their arrival.
* These peoples were isolated from the Old World's modern humans for the next 10,000 years or so in Northern North America and the next 12,500 years or more in South America.
* There are isolated instances where the evidence seems to point to the existence a pre-Last Glacial Maximum modern human population in the Americas perhaps as old as 25,000 years ago on the eastern coast of the Americas, e.g. in Virginia and Brazil. The evidence is disputed and the wider impact, ecological or cultural, or genetic appears to have been negligible.
* The time depth of Amerind proto-languages, if any, is too great to demonstrate the connection of Amerind languages into a macro-language family. Linguistic drift has left Amerind languages with every possible combination of language features.
* While up to six pre-Columbian waves of Old World contact have impacted Canada and Alaska, and as many as three have impacted the remainder of North America, just two or three have had an impact on Latin America in pre-Columbian times, and all but one of those contacts was pretty much restricted to Peru.
New World Redux
This is a fairly comprehensive account of the pre-Columbian contacts between the New World and Old World. We also have a much more detailed since of the greater historical trends within the New World.
Europe
Pieces are also coming together in Europe.
First Wave Farmers
Ancient DNA evidence reveals that the first wave of farmers and herders to arrive in Europe both in Central Europe and on the Southern European coast, were predominantly Y-DNA G2a and F with some Y-DNA I1 and I2, and carried the same highly diverse suite of mtDNA types.[8]
This was assembled into a coherent genetic population by the 5000s BCE that sharply contrasts with the Mesolithic hunter-gather population of Europe dominated by Y-DNA I2 and mtDNA U5b.[8] The first wave of farmers probably brought about the demise of all of the languages of Europe's Mesolithic hunter-gathers and dramatically reduced their contribution to the European gene pool. The hunter-gather populations and farmer populations show little admixture with each other in the early period, although admixture with hunter-gatherer women is greater towards the LBK frontier in north central Europe.[8] Populations that were side by side geographically maintained genetic distinctions between hunter-gatherers and farmers for at least a thousand years.
Y-DNA I1, which is now most common in Scandinavia, apparently arose not locally, but as part of the five wave Neolithic population assembled in Hungary or further to the Southwest, that died out elsewhere but thrived in Scandinavia due to serial founder effects.
The first wave of farmers and herders to arrive in Europe give rise to an intense population boom,[11] almost universally followed a few centuries later, by a dramatic population bust.[11] In some places, the population reverted to hunting and gathering, while in others, farming and herding remained the main means of food production, but populations fell although not to hunting and gathering levels.
Early Neolithic and Bronze Age Crete
Ultimately, the package of crops and technologies that produced the Neolithic revolution in Europe were derived from a package assembled mostly in the Fertile Crescent of SW Asia. A small sample of 15 ancient mtDNA samples from 8000 BCE in the Fertile Crescent Neolithic favors a maritime migration route of first wave farmers into Europe via Cyprus, Crete and the Aegean, rather than via Anatolia.[9]
A different Bronze Age Minoan mtDNA sample (N=37), five thousand years later, however, mostly by virtue of being so rich in mtDNA haplogroup H, more closely resembles second wave farming populations of Bronze Age Europe (as well and a particular affinity to Northern and Western European populations, as well as to modern Kurdish populations) than first wave Neolithic populations, and is also almost identical to the current population of the part of Crete from which the ancient DNA samples were obtained, a modern population also rich in a European clade of Y-DNA R1b.[10]
The Caucasus And The Vicinity In The Copper Age
The first farmers were most similar genetically to the peoples of the Caucasus mountains and Northern Anatolia today[8], although the population genetic landscape of Europe would have been different then.
This could mean that the first farmers originated in the Caucasus mountains, but could also simply mean that the Caucasus and a few other European populations like the Sardinians, are relict populations that escaped the genetic transformations of the next wave of metal using farmers that followed the initial Neolithic population bust in Europe due to their isolation and distinct climate niches.
A critical moment in the history of the Caucasus region was the Maikop culture (3700 BCE to 3000 BCE) of the Northern Caucasus which was an instrumental influence in early metallurgy development that spread to the contemporaneous and neighboring Yamna culture of the Pontic Steppe which is in the Kurgan hypothesis proto-Indo-European (the Maikop people possibly also spread metallurgy technology to other early adopters of metal age technology such as the Bell Beaker people). The Maikop culture also appears to have been the first to adopt the Kurgan burial practices that subsequently came to be a litmus tests for early Indo-European cultures before they adopted cremation on a widespread basis sometime around 2000 BCE or earlier.[12]
There does not appear to be any archaeological evidence to support the claim that the Maikop culture was derived from and strongly influenced by the contemporaneous Uruk culture of the Sumerians of Mesopotamia, which instead arose independently of the Sumerians or the Balkan-Anatolian copper age, with influences mostly from Iran and South Central Asia.[13] But, there is evidence to support the claim that there were trade ties (or more) between the Kura-Araxes culture of the Southern Caucasus (i.e. the modern Republic of Georgia) and adjacent parts of Iran and Eastern Anatolia did have longstanding and sustained ties to this Sumerian Uruk culture.[13]
The Population Genetic Impact of Metal Age Second Wave Farmers
Sometime between the population bottleneck followed by the collapse of the first wave Neolithic in Europe and the end of the Bronze Age, there was a second major shift in European population genetics that caused Western and Northern Europe to be dominated by Y-DNA R1b, caused Central and Eastern Europe to be dominated by Y-DNA R1a, introduced Y-DNA E and J to Europe, and caused mtDNA to become the predominant mtDNA type across Europe.
Since the origins of Y-DNA R1b (West Asia), E (North and East Africa), J2 (West Asia) ad J1 (SW Asia) (with the transition from J2 to J1 being somewhat clinal) are so different geographically, they may have arrived in separate migration waves in this time period, and both E and J could be somewhat later arrivals (for the most part) than R1a and R1b in areas where R1a and/or R1b are predominant singly or in combination.
In Central and Eastern Europe, this genetic transition generally attributed to Indo-Europeans particularly in the Corded Ware culture (ca. 2900 BCE to 2400 BCE), a metal using culture fairly directly emerging from the Indo-European urheimat. Ancient DNA evidence reported in a newly announced conference paper confirms this analysis:
From [15]
There are two groups of significant outliers to this model, however (from the same link) (which also does not seem to include any Roma populations with affinities to South Asia or more recent immigrant populations):
The Bell Beaker culture and its successors in continuity with it, which was probably Vasconic (i.e. linguistically related to Basque) rather than Indo-European linguistically, expanded across a generally Western and Northern European territory and held off Indo-Europeans associated with the Corded Ware culture and related archaeological cultures for a thousand years along a fairly static border that still biogeographically divides Western Europe from Eastern Europe.
The Bell Beaker culture expanded out of Southern Portugal across Europe. But, the origins of the Bell Beaker culture prior to its expansion out of Portugal are unclear. Indigenous origins, origins in Western Sahara, and origins in Bohemia and more remotely in the Caucasus Mountains, have been suggested.
By the time the Iron Age arrived following Bronze Age collapse ca. 1200 BCE, the population genetics of Europe were generally similar to those today prior to historic era migrations. Indo-Europeans came to linguistically and culturally dominate the formerly Bell Beaker territory around this time, but seem to have had quite a modest population genetic impact.
The Urnfield Culture ca. 1300 BCE, in the region shown on the map below, via Wikipedia, which may have been linguistically proto-Celtic, was probably one of the first Indo-European cultures in Western Europe.
Y-DNA E and J in Europe
Y-DNA E has a split distribution, with Y-DNA E clades in SW Europe probably arriving from NW Africa, and SE Europe probably receiving its Y-DNA E clades from NE Africa in parallel but separate migration waves, quite likely by sea.
Y-DNA J2 appears to have spread largely by maritime travel also along the Southern European coast, possibly mixed with a minority of Y-DNA J1, with a significant subset of both J2 and J1 due to the Jewish diaspora and migration (and probably due to Phoenicians before that). J2 is much more common than J1 in Europe, indicating a predominantly West Asian origin, rather than a Semitic one. The J2 and J1 divide can also be conceptualized as a divide between high country J2 populations and lowland J1 populations.
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Y-DNA haplogroup J distribution via Wikipedia.
The low levels of Y-DNA J and E in most of Europe, and their relatively late arrival, also disfavor any theory that there were substantial areas where Afro-Asiatic languages were spoken in Europe in unattested prehistory. Historic migrations of Hebrew speaking Jews, Phoenicians, Arabs/Moors, North African Romans, and Egyptians are sufficient to account for all Afro-Asiatic linguistic influences in Europe and their histories are older than almost any other part of the world.
The scarcity of Y-DNA J and G in the Basque population tends to disfavor of Middle Eastern or West Asian origin for their Y-DNA R1b carrying patriline ancestors. But, genetic diversity of R1b supports an origin for the haplogroup in the East of Europe and Central Asia, rather than in Western Europe as an indigenous Y-DNA type there.
The lack of Y-DNA R1b in Western Sahara apart from Chadic R1b-V88 which is very distinct from European Y-DNA R1b, the absence of any evidence of pre-Phoenician Afro-Asiatic linguistics in the Bell Beaker area (or any evidence of Semitic languages away from coastal areas), the lack of a strong metal processing tradition in copper age Western Sahara all point away from Bell Beaker origins there in my humble opinion.
Y-DNA H in Europe
Y-DNA H, which is common in South Asia, is found in Europe is due almost entirely to historic era Roma (aka Gypsy) migrations in the current era.
The Uralic Langauges In Europe
The timing and manner by which Uralic languages arrived in Finland, Karelia, and the Baltic area around the time of the Finnish Bronze Age ca. 1500 BCE (after about 1000 years as a linguistically Indo-European region that was part of the Corded Ware culture) is increasingly clear. Not surprisingly, given their linguistic distinctiveness and position near the Eurasian boundary, a population genetic study of 6,209 contemporary Europeans targeted at identifying fine scale structure in European populations found that:
The events giving rise to the Uralic Hungarian language in the historic era by a narrow Magyar elite are also now well understood.
Footnote On European Linguistics In Light Of Genetics
There are lots of scholars who have argued for an early appearance of Indo-European languages in Europe. I've seen it argued that the Mesolithic hunter-gatherers of Atlantic and Baltic coasts spoke Indo-European languages, that the people who kept Venus figurines spoke Indo-European languages, that the LBK and Cardial Pottery Neolithic people spoke Indo-European languages, that the Bell Beaker people spoke Indo-European languages, that the Minoans spoke Indo-European languages, and that the pre-Hittite people of Anatolia mostly spoke Indo-European languages.
Personally, I find these assertions to be highly implausible. Proto-Indo-European probably dates to around 4000-4500 BCE and was probably a minor language family of Central Asia and Eastern Europe with a narrow geographic scope until around 2000 BCE when it exploded across Europe, West Asia, South Asia, Central Asia and Siberia, expanding further at the end of the Bronze Age into Western Europe.
In Greece, we don't know much about the Minoan language, but we know enough from Egyptian phonetic translations of Minoan prayers/spells/songs and from correspondences between Linear A and Linear B, that Minoan was not an Indo-European language and bore some resemblance to the Hattic language spoken in Anatolia at the same time that Minoan palace culture thrived. We know the the Mycenean Greeks spoke an early version of ancient Indo-European Greek, and that before conquering the Minoans who had a written language, that they conquerered pre-Mycenean people of mainland Greece (the Pelopenese) around 2000 BCE, and that they were people who had a greater cultural affinity to the Greeks and hence probably spoke a non-Indo-European language. We also have substantial evidence of a strong non-Indo-European substrate influence in ancient (and modern) Greek.
We know that the Hattic language of much of Anatolia subsequently conquered by the Indo-European Hittites, which is attested in Hittite writings as a liturgical language, was non-Indo-European. Most of the Indo-European languages of Anatolia are attested only after the fall of the Hittite empire around 1200 BCE. We know from contemporary correspondence from Mesopotamian trading posts that the Hittite empire was just a tiny two town confederation around 2000 BCE.
We know that to the South and West of Anatolia, neither the Sumerian language, nor the kindred Kassite language, nor the Akkadian language that replaced the Sumerian language, nor the Coptic language spoke in Egypt, or the Phoenician language spoken by Eastern Mediterranean maritime traders who emerged out of Lebanon, were Indo-European.
We know that the Indo-Aryan Mittani language first appeared on the scene near the modern Turkish-Iranian border around 1500 BCE which was about 500 years after the archaeologically attested appearance of the Sanskrit speaking Aryan people in South Asia, and that the Indo-Iranian languages appeared in Persia around the same time (2000 BCE); these languages share a common origin around 2000 BCE. There is no positive evidence of any kind to support the argument that the Harappan language was an Indo-European language and there were no Indo-European languages spoken in South Asia or Iran that were not Indo-Iranian or Indo-Aryan until Hellanic Alexander the Great imposed Greek upon Persia ca. 300 BCE. Sanskrit also shows substrate influences not shared by other Indo-European languages again arguing for a non-Indo-European Harappan language. There is evidence that at least two non-Indo-European languages (Elamite and a newly discovered unnamed language in an Hittite era historical record) were spoken in Iran as late of the Iron Age (both of these language died in the historic era).
We know that the Basque people, who have typically Western European high levels of Y-DNA R1b and mtDNA H, preceded Indo-European language speakers in the area and never underwent the language shift seen by other peoples (nature's secret weapon by have related to rh blood type factors that reduced the viability of the pregnancies of local women with would be conquering men, in addition to a secure and remote mountainous environment to serve as a refugium that could be bypassed by subsequent Indo-European conquerors). We also know that linguistically Vasconic people were present in a larger geographic area in pre-Roman times, that a large swath of formerly Bell Beaker Europe has Vasconic place names, that there are traces of Vasconic substrate influences in the Indo-European languages of Western Europe (for example, base twenty numbers), and that the archaeological appearance with cultural traits that were litmus tests for Bronze Age Indo-Europeans like cremation, and Celtic material culture didn't start to appear in the archaeological record until about 1300 BCE in France and Spain and Italy. And, we know that this later wave of people in Western Europe didn't have much of a demic impact, suggesting something less than a blowout in terms of comparative technological and cultural superiority. We know that the megalithic culture of Western Europe was pre-Celtic.
Litmus tests for Indo-Europeans appear in proto-Germanic territory only around the Nordic Bronze Age (ca. 1500 BCE) and arguably only in the later part of the Nordic Bronze Age (ca. 1200 BCE).
We know that linguistically non-Indo-European Etruscans were present in Tuscany prior to the formation of the Roman state in the iron age, and persisted into the current era, although they may not have preceded the Italic peoples by much more than a century or two, and probably shared a language family with the linguistically non-Indo-European Rhaetic people of Alps to the North.
We know that there were other small pockets of linguistically non-Indo-European between Italy and Anatolia into the attested Roman era.
We know that the Slavic languages expanded starting around 400 CE or later, although our knowledge of what was spoken before the Slavic languages in the area into which they expanded is less solid.
There is no evidence that Indo-European languages were spoken on the North African coast prior to the expansions of Greek and Roman civilizations into those areas in the Iron Age.
We know that the linguistically Indo-European Tocharians arrive in the Tarim Basin around 2000 BCE, although they would have had to commence their expansion from an Indo-European urheimat before then. By all accounts this is the furthest eastern outpost of Indo-European languages and involved people who physically and culturally had much in common with Indo-European language speakers further west.
There is a very plausible argument to suggest that the Finns converted to an Indo-European language around 2500 BCE, only to adopt the non-Indo-European Finnish language around the time of the Finnish Bronze Age ca. 1500 BCE.
There are historically attested and linguistic reasons to suspect that the Armenian language did not come into being until after the fall of the Hittite empire.
There is good reason to doubt linguistic chronologies pointing towards an early Neolithic Anatolian origin of the Indo-European languages, both in terms of a methodology that ignores that fact that language change is heightened in the formative years of a language rather than drifting at an even rate due to a desire to be distinct from prior languages and due to substrate influences as language shift takes place. Ignoring these factors makes a language seem artificially long. The available evidence on the pre-Hittite linguistic state of Anatolia also tends to contradict the Anatolian theory.
The Kurgan theory provides plausible cultural antecedents for the Indo-European languages outside of Anatolia that are not rebutted by contradictory evidence and that are bolstered by the distribution of Y-DNA R1a which is found in ancient DNA samples from some of the oldest known Indo-European language speakers such as the Tocharian mummies and late Corded Ware peoples. The low levels of Y-DNA R1a in Western Europe also tends to disfavor the notion that second wave early metal age farmers in these regions were Indo-European linguistically.
References
[1] Maanasa Raghavan, et al., "The genetic prehistory of the New World Arctic", Science 29 August 2014: Vol. 345 no. 6200 DOI: 10.1126/science.1255832.
[2] David Reich, et al., "Reconstructing Native American population history", Nature 488, 370-374 (16 August 2012) doi: 10.1038/nature11258
[3] Matthew C. Dulik, "Y-chromosome analysis reveals genetic divergence and new founding native lineages in Athapaskan- and Eskimoan- speaking populations", PNAS (May 29, 2012) doi: 10.1073/pnas/1118760109
[4] Erika Tamm, et al., "Beringian Standstill and Spread of Native American Founders", PLOS One DO: 10.1381/journal.pone.0000829 (September 5, 2007).
[5] Alessandro Achilli, "Reconciling migration models to the Americas with the variation of North American native mitogenomes", 110 PNAS 35 (August 27, 2013) doi: 10.1073/pnas.1306290110
[6] Zegura, et al., "High-Resolution SNPs and Microsatellite Haplotypes Point to a Single, Recent Entry of Native American Y Chromsomes into the Americas.", Mol. Biol. Evol. (2004) 21(1):164-175 doi: 0.1093/molbev/msh009
[7] Judith R. Kidd, et al., "SNPs and Haplotypes in Native American Populations", Am J. Phys Anthropol. 146(4) 495-502 (Dec. 2011) doi: 10.1002/aipa/21560
[8] Anna Szécsényi-Nagy et al., "Tracing the genetic origin of Europe's first farmers reveals insights into their social organization" (2014) (via Dienekes Anthropology Blog).
[9] Eva Fernandez, et al., "Ancient DNA Analysis of 8000 B.C. Near Eastern Farmers Supports an Early Neolithic Pioneer Maritime Colonizatio of Mainland Europe through Cyprus and the Aegean Islands" PLOS Genetics (June 5, 2014) doi: 10.1371/journal.pgen.1004401
[10] Jeffery R. Hughey, et al., "A European population in Minoan Bronze Age Crete", Nature Communications (2013) doi: 10.1038/ncomms2871 (via For what they were . . . we are).
[11] Timpson et al, "Reconstructing regional population fluctuations in the European Neolithic using radiocarbon dates: a new case-study using an improved method", Journal of Archaeological Science (2014) (via Bell Beaker Blogger).
[12] Konstatine Pitskhelauri, "Uruk Migrants in the Caucuasus", 6(2) Bulletin of the Georgian National Academy of Sciences (2012) (via Dienekes Anthropology Blog)
[13] Mariya Ivanova, "Kaukasus und Orient: Die Entsthung des "Maikop-Phanomens" im 4. Jahrausend .Chr.", 87(1) Prahistorische Zeitschrift 1-28 (2013) (in German) (abstract translated at Dienekes Anthropology Blog).
[14] I. Lazaridis, et al., "Capture of 390,000 SNPS in dozens of ancient central Europeans reveals a population turnover in Europe thousands of years after the advent of farming.", American Society of Human Genetics (ASHG) 2014 Conference Abstracts (to be delivered October 18-22, 2014) (via Dienekes Anthropology Blog).
[15] Iosif Lazaridis, et al., "Ancient human genomes suggest three ancestral populations for present-day Europeans" (December 23, 2013) bioRxiv doi: http://dx.doi.org/10.1101/00155
[16] S. Leslie, et al., "Fine-scale population structure in Europe.", American Society of Human Genetics (ASHG) 2014 Conference Abstracts (to be delivered October 18-22, 2014) (via Dienekes Anthropology Blog).
This post was last updated September 11, 2014.
We've come a long way since the only tools we had to address this were the Bible, manuscripts copied by generations of monks from the Greco-Roman era, and letters from world travelers.
New World Prehistory
Arctic Genetic Prehistory
Some of the most definitive answers about the prehistory of the Americas came in an analysis of ancient DNA and modern population genetics released a couple of weeks ago.[1] This study established that:
1. The Saqqaq and Dorest Paleo-Eskimo populations were a single, closely genetically related migration wave, that arrived in Arctic North America around 3500 BCE and persisted until about 500 CE, despite the marked break in archaeological culture between the sequential populations. These Paleo-Eskimos had surprisingly little genetic admixture with either pre-existing Native American populations, or with the proto-Inuits who ultimately replaced them in the Arctic - consistent with Inuit legends describing a distinct arctic people who kept themselves separate from other peoples
2. The 6th to 7th century CE Berginian Birnirk culture (in turn derived from Siberian populations) is the source of the proto-Inuit Thule people, who were the last substantial and sustained pre-Columbian peoples to migrate to the Americas.
3. "Although we cannot preclude later gene flow between the Dorset and the Thule (that is, subsequent to the more ancient gene flow that occurred at least 4000 years ago), the contrasting genetic and cultural affinities of the Sadlermiut individuals present a conundrum. This culture that went extinct in 1903 CE from European disease has long been considered Thule-acculturated Dorset people, likely due to intermarriage; however, genetic evidence from this study suggests that they were Thule people who had somehow acquired Dorset stone technology."
The Na-Dene people
The Na-Dene people (aka Athapaskans) do not have significant Paleo-Eskimo admixture.[1] This can be added to some other notable data points in the existing literature about the Na-Dene:
* Genetic and linguistic evidence establish that the Na-Dene people are distinct not only from Paleo-Eskimos and the Inuit, but also from other Native Americans. While the Na-Dene are heavily admixed with pre-existing Native American populations, there are genetic indicators of a wave of Na-Dene migration long after the original peopling of the Americas by modern humans ca. 15,000-18,000 years ago. About 10% of Na-Dene ancestry is distinct from the initial founding population of the Americas.[2] The Na-Dene, like Inuits, have Y-DNA haplogroups that are specific to them and of more recent origin that the founding Y-DNA haplogroups of the Americas.[3]
* Linguistic evidence establishes that the Na-Dene people's expansion is North America originated in Western Alaska and moved east from there to the rest of Alaska, Western Canada, and the Pacific Northwest.
* The earliest archaeological evidence of Na-Dene people in Alaska comes from the general vicinity of Wrangell-St. Elias National Park in Southern Alaska around 1500 BCE although arguably they were present in the Southwestern Yukon in Canada as early as 2500 BCE.
* The Na-Dene languages are related to the Yenesian languages of the Ket people of Siberia, a Paleo-Siberian population that was exiled from general vicinity of the Altai Mountain region of Southern Siberia to Siberia's Yenesian River area around 0 CE, according to the oral histories of the Ket people. The strength of the linguistic connection is consistent with a divergence of the two language families from a common origin around 3500-4000 years ago, a similar time depth, for example, to the division between Latin and Gaelic in the Indo-European language family.
* Substantial admixture with local populations by both the Ket people and that Na-Dene people, however, has obscured any common genetic linkages of these peoples, which would already have been difficult to detect using the crude 1993 genetic tests of the Ket people applied to a small sample that was used to make the comparison.
* The Na-Dene people migrated in two parallel waves from different parts of Western Canada to the American Southwest around 1000 CE. Their descendants are the Apache and Navajo tribes.
Other New World Contacts
* Around 1000 CE, Lief Erickson led a small population of Vikings to a short lived agricultural settlement called Vinland in maritime Canada. Recent discoveries announced in National Geographic in November of 2012 established that there were trade relations between the Vikings and indigeneous Arctic people at around the same time at the Northern tip of Canada's Baffin Island.
* From around 900 CE to 1100 CE, the "people who lived more than 1,000 years ago in what today is the Lambayeque region, about 800 kilometers (500 miles) north of Lima, had genetic links to the contemporaneous populations of Ecuador, Colombia, Siberia, Taiwan and to the Ainu people of northern Japan." These people were practitioners of the Middle Sican culture, a cultural renaissance in the region marked by veneration of "Sican diety" and "Sican lord" with vaguely Asian eyes in material cultural items including pottery and metalwork, who reputedly came to them from across the ocean via a balsa wood raft. (Earlier ancient mtDNA work here and here). A few hundred years later, however, the Sican diety cult abated.
Sicán iconography is dominated by the Sican Deity. It decorates all artistic media of the Sicán, including ceramics, metal works, and textiles. The icon is most commonly represented with a mask face and upturned eyes. Sometimes it may be shown with avian features, such as beaks, wings, and talons, which are evident in Early Sicán ceramics. These avian features are related to Naylamp, the key figure in Sicán mythology. Naylamp was said to be the founder of the first dynasty of prehistoric kings in La Leche and Lambayeque valleys. In The Legend of Naylamp, first recorded in the 16th century by the Spanish chronicler Miguel Cabello de Balboa, Naylamp is said to have traveled on a balsa raft by sea to the Lambayeque shores. He founded a large city, and the 12 sons of his eldest son each founded a new city in the Lambayeque region. When Naylamp died, he sprouted wings and flew off to another world (Nickle Arts Museum 2006, p. 18 and 65).* Late in the period of Austronesian expansion (probably not earlier than 700 CE, with radiocarbon dated examples found in the Cook Islands by 1000 CE), perhaps from a final launching point at Easter Island, the kumara, a yam-like plant native to South America and possibly native to Peru, entered Austronesian territory and became a staple food. But, no genetic traces of the New World are found in Austronesian populations. It is possible that the kumara's arrival in Oceania and the Asian genetic influences found in Middle Sican graves involved the same instance of cultural Old World-New World contact.
The First Americans
* The remaining peoples of the Americas, with a quite small founding population, crossed the Berginian land bridge from Northeast Asia, were bottled up there cutoff by cold and glaciers from both Asia and the rest of North America, and then migrated to the rest of the Americas once the glaciers subsided enough to allow them to pass to the rest of the continent.[4] One group took a Pacific coastal route that reached South America within about a thousand years.[4] The other made their way to eastern North America and moved Westward starting around the time of the emergence of the Clovis culture.
Some investigators, such as those conducting a 2013 mtDNA analysis have argued that the Indigeneous peoples of South America have only a subset of the first Americans whose full range of Y-DNA and mtDNA diversity is preserved only in North America and is attributable to a wave of inland migration limited to North America.[5] In particular, they see mtDNA X2a and C4c as markers of this migration.[5] This areal distinction predates and is not difference between Na-Dene and non-Na-Dene people, and instead derived from local Na-Dene admixture with other Native American populations.[5] High coverage autosomal data in a 2013 study do show some North-South cline in the Americas, but not a lot of distinct population structure.[7]
In contrast, a 2007 paper argued instead that there was no population genetic structure in the founding population of the Americas, at least at the major mtDNA clade level. [4] A 2004 Y-DNA analysis came to a similar conclusion.[6] It is not clear if apparent differences in diversity are a serial founder effect, or if the greater genetic diversity in North American Native Americans reflects a Beringian population that he some population structure consisting of at least two distinct peoples when the path from Beringia to North America opened up, or if apparent structure is simply illusory.
* The first Americans brought dogs, but not horses, and were hunter-gatherers. Mega-fauna extinction across the Americas followed their arrival.
* These peoples were isolated from the Old World's modern humans for the next 10,000 years or so in Northern North America and the next 12,500 years or more in South America.
* There are isolated instances where the evidence seems to point to the existence a pre-Last Glacial Maximum modern human population in the Americas perhaps as old as 25,000 years ago on the eastern coast of the Americas, e.g. in Virginia and Brazil. The evidence is disputed and the wider impact, ecological or cultural, or genetic appears to have been negligible.
* The time depth of Amerind proto-languages, if any, is too great to demonstrate the connection of Amerind languages into a macro-language family. Linguistic drift has left Amerind languages with every possible combination of language features.
* While up to six pre-Columbian waves of Old World contact have impacted Canada and Alaska, and as many as three have impacted the remainder of North America, just two or three have had an impact on Latin America in pre-Columbian times, and all but one of those contacts was pretty much restricted to Peru.
New World Redux
This is a fairly comprehensive account of the pre-Columbian contacts between the New World and Old World. We also have a much more detailed since of the greater historical trends within the New World.
Europe
Pieces are also coming together in Europe.
First Wave Farmers
Ancient DNA evidence reveals that the first wave of farmers and herders to arrive in Europe both in Central Europe and on the Southern European coast, were predominantly Y-DNA G2a and F with some Y-DNA I1 and I2, and carried the same highly diverse suite of mtDNA types.[8]
This was assembled into a coherent genetic population by the 5000s BCE that sharply contrasts with the Mesolithic hunter-gather population of Europe dominated by Y-DNA I2 and mtDNA U5b.[8] The first wave of farmers probably brought about the demise of all of the languages of Europe's Mesolithic hunter-gathers and dramatically reduced their contribution to the European gene pool. The hunter-gather populations and farmer populations show little admixture with each other in the early period, although admixture with hunter-gatherer women is greater towards the LBK frontier in north central Europe.[8] Populations that were side by side geographically maintained genetic distinctions between hunter-gatherers and farmers for at least a thousand years.
Y-DNA I1, which is now most common in Scandinavia, apparently arose not locally, but as part of the five wave Neolithic population assembled in Hungary or further to the Southwest, that died out elsewhere but thrived in Scandinavia due to serial founder effects.
The first wave of farmers and herders to arrive in Europe give rise to an intense population boom,[11] almost universally followed a few centuries later, by a dramatic population bust.[11] In some places, the population reverted to hunting and gathering, while in others, farming and herding remained the main means of food production, but populations fell although not to hunting and gathering levels.
Early Neolithic and Bronze Age Crete
Ultimately, the package of crops and technologies that produced the Neolithic revolution in Europe were derived from a package assembled mostly in the Fertile Crescent of SW Asia. A small sample of 15 ancient mtDNA samples from 8000 BCE in the Fertile Crescent Neolithic favors a maritime migration route of first wave farmers into Europe via Cyprus, Crete and the Aegean, rather than via Anatolia.[9]
A different Bronze Age Minoan mtDNA sample (N=37), five thousand years later, however, mostly by virtue of being so rich in mtDNA haplogroup H, more closely resembles second wave farming populations of Bronze Age Europe (as well and a particular affinity to Northern and Western European populations, as well as to modern Kurdish populations) than first wave Neolithic populations, and is also almost identical to the current population of the part of Crete from which the ancient DNA samples were obtained, a modern population also rich in a European clade of Y-DNA R1b.[10]
The Caucasus And The Vicinity In The Copper Age
The first farmers were most similar genetically to the peoples of the Caucasus mountains and Northern Anatolia today[8], although the population genetic landscape of Europe would have been different then.
This could mean that the first farmers originated in the Caucasus mountains, but could also simply mean that the Caucasus and a few other European populations like the Sardinians, are relict populations that escaped the genetic transformations of the next wave of metal using farmers that followed the initial Neolithic population bust in Europe due to their isolation and distinct climate niches.
A critical moment in the history of the Caucasus region was the Maikop culture (3700 BCE to 3000 BCE) of the Northern Caucasus which was an instrumental influence in early metallurgy development that spread to the contemporaneous and neighboring Yamna culture of the Pontic Steppe which is in the Kurgan hypothesis proto-Indo-European (the Maikop people possibly also spread metallurgy technology to other early adopters of metal age technology such as the Bell Beaker people). The Maikop culture also appears to have been the first to adopt the Kurgan burial practices that subsequently came to be a litmus tests for early Indo-European cultures before they adopted cremation on a widespread basis sometime around 2000 BCE or earlier.[12]
There does not appear to be any archaeological evidence to support the claim that the Maikop culture was derived from and strongly influenced by the contemporaneous Uruk culture of the Sumerians of Mesopotamia, which instead arose independently of the Sumerians or the Balkan-Anatolian copper age, with influences mostly from Iran and South Central Asia.[13] But, there is evidence to support the claim that there were trade ties (or more) between the Kura-Araxes culture of the Southern Caucasus (i.e. the modern Republic of Georgia) and adjacent parts of Iran and Eastern Anatolia did have longstanding and sustained ties to this Sumerian Uruk culture.[13]
The Population Genetic Impact of Metal Age Second Wave Farmers
Sometime between the population bottleneck followed by the collapse of the first wave Neolithic in Europe and the end of the Bronze Age, there was a second major shift in European population genetics that caused Western and Northern Europe to be dominated by Y-DNA R1b, caused Central and Eastern Europe to be dominated by Y-DNA R1a, introduced Y-DNA E and J to Europe, and caused mtDNA to become the predominant mtDNA type across Europe.
Since the origins of Y-DNA R1b (West Asia), E (North and East Africa), J2 (West Asia) ad J1 (SW Asia) (with the transition from J2 to J1 being somewhat clinal) are so different geographically, they may have arrived in separate migration waves in this time period, and both E and J could be somewhat later arrivals (for the most part) than R1a and R1b in areas where R1a and/or R1b are predominant singly or in combination.
In Central and Eastern Europe, this genetic transition generally attributed to Indo-Europeans particularly in the Corded Ware culture (ca. 2900 BCE to 2400 BCE), a metal using culture fairly directly emerging from the Indo-European urheimat. Ancient DNA evidence reported in a newly announced conference paper confirms this analysis:
To understand the population transformations that took place in Europe since the early Neolithic, we used . . . DNA from a number of different archaeological cultures of central Europe (Germany and Hungary). The samples spanned the time period from 7,500 BP to 3,500 BP (Early Neolithic to Early Bronze Age periods) and most of them were previously studied using mtDNA (Brandt, Haak et al., Science, 2013). . . . By analyzing this data together with a dataset of 2,345 present-day humans and other published ancient genomes, we show that late Neolithic inhabitants of central Europe belonging to the Corded Ware culture were not a continuation of the earlier occupants of the region. Our results highlight the importance of migration and major population turnover in Europe long after the arrival of farming.[14]The Corded Ware culture is also a likely principle source of one of the three main autosomal genetic ancestry components in Europe - "Ancestral Northern Europeans (ANE)" ("In Europe today it peaks among Estonians at just over 18%, and, intriguingly, reaches a similar level among Scots. However, numbers weren't given for Finns, Russians and Mordovians, who, according to one of the maps, also carry very high ANE, but their results are confounded by more recent Siberian admixture"), which together with Western European Hunter-Gatherers (WHG) from Mesolithic Western Europe ("today the WHG component peaks among Estonians and Lithuanians, in the East Baltic region, at almost 50%"), and Early European Farmers (EEF) ("today peaks at just over 80% among Sardinians. Apart from the Stuttgart sample, the EEF meta-population includes Oetzi the Iceman and a Neolithic Funnelbeaker farmer from Sweden."),[15] contribute most of Europe's population genetic ancestry.
From [15]
There are two groups of significant outliers to this model, however (from the same link) (which also does not seem to include any Roma populations with affinities to South Asia or more recent immigrant populations):
While our three-way mixture model fits the data for most European populations, two sets of populations are poor fits.
First, Sicilians, Maltese, and Ashkenazi Jews have EEF estimates beyond the 0-100% interval and they cannot be jointly fit with other Europeans. These populations may have more Near Eastern ancestry than can be explained via EEF admixture, an inference that is also suggested by the fact that they fall in the gap between European and Near Eastern populations in the PCA of Fig. 1B.In Western Europe, the source of this genetic transformation is less clear. The Bell Beaker culture (ca. 2800 BCE to 1800 BCE) and its successors prior to Bronze Age collapse (see below) is in roughly the right places at the right time, but was not commonly been associated with mass demic transformation in academic circles in the last 20th century and the early 21st century before ancient DNA samples suggested otherwise over the last decade or so. However, it also isn't clear at all what the genetic make up of Atlantic Neolithic megalithic culture peoples was like before Bell Beaker cultures appeared.
Second, we observe that Finns, Mordovians, Russians, Chuvash, and Saami from northeastern Europe do not fit our model. To better understand this, for each West Eurasian population in turn we plotted f4(X, Bedouin2; Han, Mbuti) against f4(X, Bedouin2; MA1, Mbuti), using statistics that measure the degree of a European population’s allele sharing with Han Chinese or MA1. Europeans fall along a line of slope >1 in the plot of these two statistics. However, northeastern Europeans fall away from this line in the direction of Han. This is consistent with Siberian gene flow into some northeastern Europeans after the initial ANE admixture, and may be related to the fact that Y-chromosome haplogroup N is shared between Siberian and northeastern Europeans but not with western Europeans. There may in fact be multiple layers of Siberian gene flow into northeastern Europe after the initial ANE gene flow, as our analyses . . . show that some Mordovians, Russians and Chuvash have Siberian-related admixture that is significantly more recent than that in Finns.
The Bell Beaker culture and its successors in continuity with it, which was probably Vasconic (i.e. linguistically related to Basque) rather than Indo-European linguistically, expanded across a generally Western and Northern European territory and held off Indo-Europeans associated with the Corded Ware culture and related archaeological cultures for a thousand years along a fairly static border that still biogeographically divides Western Europe from Eastern Europe.
The Bell Beaker culture expanded out of Southern Portugal across Europe. But, the origins of the Bell Beaker culture prior to its expansion out of Portugal are unclear. Indigenous origins, origins in Western Sahara, and origins in Bohemia and more remotely in the Caucasus Mountains, have been suggested.
By the time the Iron Age arrived following Bronze Age collapse ca. 1200 BCE, the population genetics of Europe were generally similar to those today prior to historic era migrations. Indo-Europeans came to linguistically and culturally dominate the formerly Bell Beaker territory around this time, but seem to have had quite a modest population genetic impact.
The Urnfield Culture ca. 1300 BCE, in the region shown on the map below, via Wikipedia, which may have been linguistically proto-Celtic, was probably one of the first Indo-European cultures in Western Europe.
Y-DNA E and J in Europe
Y-DNA E has a split distribution, with Y-DNA E clades in SW Europe probably arriving from NW Africa, and SE Europe probably receiving its Y-DNA E clades from NE Africa in parallel but separate migration waves, quite likely by sea.
Y-DNA J2 appears to have spread largely by maritime travel also along the Southern European coast, possibly mixed with a minority of Y-DNA J1, with a significant subset of both J2 and J1 due to the Jewish diaspora and migration (and probably due to Phoenicians before that). J2 is much more common than J1 in Europe, indicating a predominantly West Asian origin, rather than a Semitic one. The J2 and J1 divide can also be conceptualized as a divide between high country J2 populations and lowland J1 populations.
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The low levels of Y-DNA J and E in most of Europe, and their relatively late arrival, also disfavor any theory that there were substantial areas where Afro-Asiatic languages were spoken in Europe in unattested prehistory. Historic migrations of Hebrew speaking Jews, Phoenicians, Arabs/Moors, North African Romans, and Egyptians are sufficient to account for all Afro-Asiatic linguistic influences in Europe and their histories are older than almost any other part of the world.
The scarcity of Y-DNA J and G in the Basque population tends to disfavor of Middle Eastern or West Asian origin for their Y-DNA R1b carrying patriline ancestors. But, genetic diversity of R1b supports an origin for the haplogroup in the East of Europe and Central Asia, rather than in Western Europe as an indigenous Y-DNA type there.
The lack of Y-DNA R1b in Western Sahara apart from Chadic R1b-V88 which is very distinct from European Y-DNA R1b, the absence of any evidence of pre-Phoenician Afro-Asiatic linguistics in the Bell Beaker area (or any evidence of Semitic languages away from coastal areas), the lack of a strong metal processing tradition in copper age Western Sahara all point away from Bell Beaker origins there in my humble opinion.
Y-DNA H in Europe
Y-DNA H, which is common in South Asia, is found in Europe is due almost entirely to historic era Roma (aka Gypsy) migrations in the current era.
The Uralic Langauges In Europe
The timing and manner by which Uralic languages arrived in Finland, Karelia, and the Baltic area around the time of the Finnish Bronze Age ca. 1500 BCE (after about 1000 years as a linguistically Indo-European region that was part of the Corded Ware culture) is increasingly clear. Not surprisingly, given their linguistic distinctiveness and position near the Eurasian boundary, a population genetic study of 6,209 contemporary Europeans targeted at identifying fine scale structure in European populations found that:
[T]he Finns are the most differentiated from the rest of Europe (as might be expected); [there is] a clear divide between Sweden/Norway and the rest of Europe (including Denmark); and an obvious distinction between southern and northern Europe. We also observe considerable structure within countries on a hitherto unseen fine-scale - for example genetically distinct groups are detected along the coast of Norway.[16]
The events giving rise to the Uralic Hungarian language in the historic era by a narrow Magyar elite are also now well understood.
Footnote On European Linguistics In Light Of Genetics
There are lots of scholars who have argued for an early appearance of Indo-European languages in Europe. I've seen it argued that the Mesolithic hunter-gatherers of Atlantic and Baltic coasts spoke Indo-European languages, that the people who kept Venus figurines spoke Indo-European languages, that the LBK and Cardial Pottery Neolithic people spoke Indo-European languages, that the Bell Beaker people spoke Indo-European languages, that the Minoans spoke Indo-European languages, and that the pre-Hittite people of Anatolia mostly spoke Indo-European languages.
Personally, I find these assertions to be highly implausible. Proto-Indo-European probably dates to around 4000-4500 BCE and was probably a minor language family of Central Asia and Eastern Europe with a narrow geographic scope until around 2000 BCE when it exploded across Europe, West Asia, South Asia, Central Asia and Siberia, expanding further at the end of the Bronze Age into Western Europe.
In Greece, we don't know much about the Minoan language, but we know enough from Egyptian phonetic translations of Minoan prayers/spells/songs and from correspondences between Linear A and Linear B, that Minoan was not an Indo-European language and bore some resemblance to the Hattic language spoken in Anatolia at the same time that Minoan palace culture thrived. We know the the Mycenean Greeks spoke an early version of ancient Indo-European Greek, and that before conquering the Minoans who had a written language, that they conquerered pre-Mycenean people of mainland Greece (the Pelopenese) around 2000 BCE, and that they were people who had a greater cultural affinity to the Greeks and hence probably spoke a non-Indo-European language. We also have substantial evidence of a strong non-Indo-European substrate influence in ancient (and modern) Greek.
We know that the Hattic language of much of Anatolia subsequently conquered by the Indo-European Hittites, which is attested in Hittite writings as a liturgical language, was non-Indo-European. Most of the Indo-European languages of Anatolia are attested only after the fall of the Hittite empire around 1200 BCE. We know from contemporary correspondence from Mesopotamian trading posts that the Hittite empire was just a tiny two town confederation around 2000 BCE.
We know that to the South and West of Anatolia, neither the Sumerian language, nor the kindred Kassite language, nor the Akkadian language that replaced the Sumerian language, nor the Coptic language spoke in Egypt, or the Phoenician language spoken by Eastern Mediterranean maritime traders who emerged out of Lebanon, were Indo-European.
We know that the Indo-Aryan Mittani language first appeared on the scene near the modern Turkish-Iranian border around 1500 BCE which was about 500 years after the archaeologically attested appearance of the Sanskrit speaking Aryan people in South Asia, and that the Indo-Iranian languages appeared in Persia around the same time (2000 BCE); these languages share a common origin around 2000 BCE. There is no positive evidence of any kind to support the argument that the Harappan language was an Indo-European language and there were no Indo-European languages spoken in South Asia or Iran that were not Indo-Iranian or Indo-Aryan until Hellanic Alexander the Great imposed Greek upon Persia ca. 300 BCE. Sanskrit also shows substrate influences not shared by other Indo-European languages again arguing for a non-Indo-European Harappan language. There is evidence that at least two non-Indo-European languages (Elamite and a newly discovered unnamed language in an Hittite era historical record) were spoken in Iran as late of the Iron Age (both of these language died in the historic era).
We know that the Basque people, who have typically Western European high levels of Y-DNA R1b and mtDNA H, preceded Indo-European language speakers in the area and never underwent the language shift seen by other peoples (nature's secret weapon by have related to rh blood type factors that reduced the viability of the pregnancies of local women with would be conquering men, in addition to a secure and remote mountainous environment to serve as a refugium that could be bypassed by subsequent Indo-European conquerors). We also know that linguistically Vasconic people were present in a larger geographic area in pre-Roman times, that a large swath of formerly Bell Beaker Europe has Vasconic place names, that there are traces of Vasconic substrate influences in the Indo-European languages of Western Europe (for example, base twenty numbers), and that the archaeological appearance with cultural traits that were litmus tests for Bronze Age Indo-Europeans like cremation, and Celtic material culture didn't start to appear in the archaeological record until about 1300 BCE in France and Spain and Italy. And, we know that this later wave of people in Western Europe didn't have much of a demic impact, suggesting something less than a blowout in terms of comparative technological and cultural superiority. We know that the megalithic culture of Western Europe was pre-Celtic.
Litmus tests for Indo-Europeans appear in proto-Germanic territory only around the Nordic Bronze Age (ca. 1500 BCE) and arguably only in the later part of the Nordic Bronze Age (ca. 1200 BCE).
We know that linguistically non-Indo-European Etruscans were present in Tuscany prior to the formation of the Roman state in the iron age, and persisted into the current era, although they may not have preceded the Italic peoples by much more than a century or two, and probably shared a language family with the linguistically non-Indo-European Rhaetic people of Alps to the North.
We know that there were other small pockets of linguistically non-Indo-European between Italy and Anatolia into the attested Roman era.
We know that the Slavic languages expanded starting around 400 CE or later, although our knowledge of what was spoken before the Slavic languages in the area into which they expanded is less solid.
There is no evidence that Indo-European languages were spoken on the North African coast prior to the expansions of Greek and Roman civilizations into those areas in the Iron Age.
We know that the linguistically Indo-European Tocharians arrive in the Tarim Basin around 2000 BCE, although they would have had to commence their expansion from an Indo-European urheimat before then. By all accounts this is the furthest eastern outpost of Indo-European languages and involved people who physically and culturally had much in common with Indo-European language speakers further west.
There is a very plausible argument to suggest that the Finns converted to an Indo-European language around 2500 BCE, only to adopt the non-Indo-European Finnish language around the time of the Finnish Bronze Age ca. 1500 BCE.
There are historically attested and linguistic reasons to suspect that the Armenian language did not come into being until after the fall of the Hittite empire.
There is good reason to doubt linguistic chronologies pointing towards an early Neolithic Anatolian origin of the Indo-European languages, both in terms of a methodology that ignores that fact that language change is heightened in the formative years of a language rather than drifting at an even rate due to a desire to be distinct from prior languages and due to substrate influences as language shift takes place. Ignoring these factors makes a language seem artificially long. The available evidence on the pre-Hittite linguistic state of Anatolia also tends to contradict the Anatolian theory.
The Kurgan theory provides plausible cultural antecedents for the Indo-European languages outside of Anatolia that are not rebutted by contradictory evidence and that are bolstered by the distribution of Y-DNA R1a which is found in ancient DNA samples from some of the oldest known Indo-European language speakers such as the Tocharian mummies and late Corded Ware peoples. The low levels of Y-DNA R1a in Western Europe also tends to disfavor the notion that second wave early metal age farmers in these regions were Indo-European linguistically.
References
[1] Maanasa Raghavan, et al., "The genetic prehistory of the New World Arctic", Science 29 August 2014: Vol. 345 no. 6200 DOI: 10.1126/science.1255832.
[2] David Reich, et al., "Reconstructing Native American population history", Nature 488, 370-374 (16 August 2012) doi: 10.1038/nature11258
[3] Matthew C. Dulik, "Y-chromosome analysis reveals genetic divergence and new founding native lineages in Athapaskan- and Eskimoan- speaking populations", PNAS (May 29, 2012) doi: 10.1073/pnas/1118760109
[4] Erika Tamm, et al., "Beringian Standstill and Spread of Native American Founders", PLOS One DO: 10.1381/journal.pone.0000829 (September 5, 2007).
[5] Alessandro Achilli, "Reconciling migration models to the Americas with the variation of North American native mitogenomes", 110 PNAS 35 (August 27, 2013) doi: 10.1073/pnas.1306290110
[6] Zegura, et al., "High-Resolution SNPs and Microsatellite Haplotypes Point to a Single, Recent Entry of Native American Y Chromsomes into the Americas.", Mol. Biol. Evol. (2004) 21(1):164-175 doi: 0.1093/molbev/msh009
[7] Judith R. Kidd, et al., "SNPs and Haplotypes in Native American Populations", Am J. Phys Anthropol. 146(4) 495-502 (Dec. 2011) doi: 10.1002/aipa/21560
[8] Anna Szécsényi-Nagy et al., "Tracing the genetic origin of Europe's first farmers reveals insights into their social organization" (2014) (via Dienekes Anthropology Blog).
[9] Eva Fernandez, et al., "Ancient DNA Analysis of 8000 B.C. Near Eastern Farmers Supports an Early Neolithic Pioneer Maritime Colonizatio of Mainland Europe through Cyprus and the Aegean Islands" PLOS Genetics (June 5, 2014) doi: 10.1371/journal.pgen.1004401
[10] Jeffery R. Hughey, et al., "A European population in Minoan Bronze Age Crete", Nature Communications (2013) doi: 10.1038/ncomms2871 (via For what they were . . . we are).
[11] Timpson et al, "Reconstructing regional population fluctuations in the European Neolithic using radiocarbon dates: a new case-study using an improved method", Journal of Archaeological Science (2014) (via Bell Beaker Blogger).
[12] Konstatine Pitskhelauri, "Uruk Migrants in the Caucuasus", 6(2) Bulletin of the Georgian National Academy of Sciences (2012) (via Dienekes Anthropology Blog)
[13] Mariya Ivanova, "Kaukasus und Orient: Die Entsthung des "Maikop-Phanomens" im 4. Jahrausend .Chr.", 87(1) Prahistorische Zeitschrift 1-28 (2013) (in German) (abstract translated at Dienekes Anthropology Blog).
[14] I. Lazaridis, et al., "Capture of 390,000 SNPS in dozens of ancient central Europeans reveals a population turnover in Europe thousands of years after the advent of farming.", American Society of Human Genetics (ASHG) 2014 Conference Abstracts (to be delivered October 18-22, 2014) (via Dienekes Anthropology Blog).
[15] Iosif Lazaridis, et al., "Ancient human genomes suggest three ancestral populations for present-day Europeans" (December 23, 2013) bioRxiv doi: http://dx.doi.org/10.1101/00155
[16] S. Leslie, et al., "Fine-scale population structure in Europe.", American Society of Human Genetics (ASHG) 2014 Conference Abstracts (to be delivered October 18-22, 2014) (via Dienekes Anthropology Blog).
This post was last updated September 11, 2014.