A handy reference from a 2013 book provides Bronze Age chronologies from a variety of places in Western Europe. It begins at different times in different places generally between 2200 BCE and 1950 BCE in Western Europe.
There is less variation in the end of the Bronze Age Western Europe, after which the Iron Age follows, with 800 BCE being typical (and almost 400 years after the time period usually described as "Bronze Age Collapse").
Wednesday, October 12, 2016
Tuesday, October 11, 2016
The Running Of The QCD Coupling Constant
A nice, comprehensive primer on the running of the QCD coupling constant is now available and runs to a mere 195 pages.
If you prefer to get right down to bottom line, the five loop beta function for the QCD coupling constant (a.k.a. the strong force coupling constant) in the MS bar renormalization scheme is also available. Notable, at the QCD scale in that renormalization scheme of about a third of one GeV, the precision of the theory is only about +/- 5%. This QCD scale, in turn, is fundamentally connected to the scale of the hadron masses.
Generically, the running of the QCD coupling constant described by this beta function differs from the Standard Model version linked above in most beyond the Standard Model theories and so comparing the data to this Standard Model prediction provides a useful experimental test of such theories.
QCD fans may also appreciate a 2013 summary of eighteen significant open problems in QCD. This article ultimately distills thirteen lessons from its eighteen puzzles (emphasis added):
We point out numerous areas wherein often-used procedures in QCD and hadron physics have been challenged. These include the following conventional assumptions.
1. The structure function of a hadron reflects only the physics of the wave function of the hadron and thus must be process independent. In fact, the observed structure functions are sensitive to rescattering processes at leading twist, which are process dependent.
2. Antishadowing is a property of the nuclear wave function and is thus process independent. In fact, as the NuTeV data show, each quark may have its own antishadowing distribution.
3. Initial-state and final-state interactions are always power-law suppressed and process independent. This hypothesis is contradicted by the Sivers effect in SIDIS and the breakdown of the Lam–Tung relation in Drell–Yan reactions.
4. High–transverse momentum hadrons always arise only from jet fragmentation. In fact, there is a significant probability that high-pT hadrons arise from hard color-transparent subprocesses. As we discuss above, direct higher-twist processes wherein the hadron wave function appears in the subprocess matrix element can explain anomalies in the fixed-xT cross section and the remarkable baryon anomaly, the large proton-to-pion ratio observed in heavy-ion collisions at RHIC.
5. The renormalization scale in QCD cannot be fixed and can only be guessed to minimize sensitivity. In fact, it can be fixed at each order in perturbation theory in a scheme-independent way that agrees with the conventional QED procedure.
6. QCD condensates must be properties of the vacuum. As we discuss above, contrary results are obtained in Bethe–Salpeter and LF analyses. The conflict with the cosmological constant highlights the need to distinguish different concepts of the vacuum obtained from the usual instant form versus the causal LF definition.
7. Infrared slavery: The QCD running coupling must diverge at long distances. This is not correct in LF holographic QCD, nor is it true if one defines the QCD coupling through an effective charge defined from experiment.
8. Nuclei can be regarded as composites of color-singlet nucleons. In fact, QCD predicts hidden-color configurations of the quarks, which can dominate short-distance nuclear reactions.
9. The real part of DVCS is an arbitrary subtraction term. In fact, local four-point photonquark scattering can lead to a novel amplitude that is constant in energy and independent of the photons’ virtuality at fixed t.
10. Heavy quark thresholds cause minimal effects. In fact, the charm and strangeness thresholds can lead to unexpectedly large competing amplitudes and striking polarization effects, such as the remarkable spin-spin correlations observed in elastic pp scattering and, at large angles, the breakdown of pQCD color transparency.
11. Gluon degrees of freedom should be manifest at all scales. In fact, the effects of soft gluons may well be sublimated in favor of the QCD confinement potential.
12. Orbital angular momentum effects are negligible. In fact, in the LF framework the hadron eigensolutions for the light quarks have orbital components that are comparable in strength to the L = 0 components.
To summarize further, in my words:13. The heavy quark sea arises only from gluon splitting and is thus confined to the low-x domain. In fact, QCD predicts contributions where the heavy quarks are multiconnected to the valence quarks and thus appear at high x.
* Many observables which one would naively assume are process independent are in fact dependent upon the process involved in QCD. (1), (2) and (3).
* Holographic light front relativistic approaches make significantly different predictions than non-relativistic or non-causal approaches in many circumstances. (6), (7) and (12).
* Detailed technical analysis of every possibility including those that might seem unnatural or irrelevant often has a measurable impact on observables in QCD. (4), (8), (9), (10), (12) and (13).
* But, sometimes technical details that seem like they should be important are not. (5) and (11).
Lost Irish Cathedral Identified
There is a good case that some newly discovered ruins are the remains of one of the larger Catholic cathedrals in Irish history, probably pre-Norman (i.e. pre-1066 CE). The earliest historically attested Christian presence in Ireland is from 430 CE, so it was probably built after then.
The building's stone foundations were subsequently looted, and its identity was lost to local recollection. But, the technology involved in building it suggests that it was almost certainly from the historic era, so, given its size, it is probably mentioned somewhere in a written recollection.
The building's stone foundations were subsequently looted, and its identity was lost to local recollection. But, the technology involved in building it suggests that it was almost certainly from the historic era, so, given its size, it is probably mentioned somewhere in a written recollection.
Genetic Evidence Links Yayoi To Northeast China
A new examination of a particular genetic marker suggests that that Yayoi component of the Japanese people that migrated there ca. 300 BCE migrated to Japan from Northeast China via Korea.
The Jomon version of the marker is also shared with Native Americans - this could indicate a Japanese contribution to the Native American founding population, or it could reflect a common origin for the populations in Northeast Asia.
The Jomon version of the marker is also shared with Native Americans - this could indicate a Japanese contribution to the Native American founding population, or it could reflect a common origin for the populations in Northeast Asia.
This data point tends to slightly disfavor an Altaic linguistic connection for Japanese, although it is hardly definitive. For example, if Korea was Altaic and the Northeast Chinese migrants experienced language shift before moving on to Japan, Japanese could still be an Altaic language. Similarly, if an Altaic language (such as the Manchu language) was spoken in that part of Northeast China at the time and it subsequently experienced language shift to a Sino-Tibetan language, an Altaic hypothesis could still be supported.
The (open access) study is:
Miyamori, Daisuke et al., Tracing Jomon and Yayoi ancestries in Japan using ALDH2 and JC virus genotype distributions 6 Investigative Genetics 14 (2015).
See also:
Timothy A. Jinam, Hideaki Kanzawa-Kiriyama and Naruya Saitou, Human genetic diversity in the Japanese Archipelago: dual structure and beyond 90 Genes Genet. Syst. 147-152 (2015) (“genetic data strongly support the dual-structure model proposed by Hanihara (1991) whereby the Hondo Japanese are the result of admixture between the Jomon and Yayoi ancestral populations. . . . The indigenous Ainu and Ryukyuan populations retain a genetic identity that most likely traces back to Jomon ancestors, while at the same time show indications of recent admixture with the Hondo Japanese. . . . The genetic substructure in the Hondo Japanese also hints at a more complex model of human migrations and interactions than the dual structure model implies”).
Monday, October 10, 2016
Gravity Modification From Quantum Gravity
Lee Smolin has a new paper on quantum gravity including the proposition that modified gravity rules giving rise to the effects summarized in the MOND toy-model should arise in Loop Quantum Gravity theories based upon a couple of different arguments, neither of which are rock solid, but both of which are basically plausible. Sabine Hossenfelder discusses the paper and related issues in a recent post at her blog, and also wrote an article for the general public on a hybrid of a gravity modification and dark matter proposal.
I share Smolin's optimism that MOND-like gravitational laws will arise out of quantum gravity, although I've been more attracted to the reasoning of Alexander Deur who sees that coming out of the self-interaction term of the graviton. But, that doesn't mean that equivalent phenomena couldn't arise out of a space-time based quantization of gravity. It is nice to see room for this arising from quantum gravity in either approach.
In Deur's approach, some dark energy effects arise from a shielding effect in the dark matter effects (also nicely explaining the "coincidence" phenomena that I am loathe to call a "problem"). In Smolin's approach, the cosmological constant is integral in giving rise to the MOND-like effect, so the chain of causation is in the opposite direction.
Why Deur's approach?
Why is Deur's approach so attractive?
Occam's Razor: it explains more, with a simpler theory, than the alternatives.
1. It can reproduce the flat rotation curves and Tully-Fisher relationship for spiral galaxies recovered in other theories with dark matter and/or modified gravity.
2. More generally, essentially all arguments for modified gravity theories relative to dark matter theories are also arguments in favor of this theory (e.g. the close relationship between luminous matter distributions and dark matter distributions and the low scatter of this relationship, the contrived assumptions necessary to make N-body dark matter simulations work, etc.).
3. It explains why satellite galaxies tend to arrange themselves in a plane of rotation around a galaxy.
4. It explains the variation in the proportion of dark matter amongst elliptical galaxies, which almost all other modified gravity and dark matter particle theories fail to do.
5. Unlike MOND which ceases to be predictive beyond the galactic scale, it correctly predicts the approximate proportion of dark matter in galactic clusters.
6. It can explain the bullet cluster entirely without resort to supplemental dark matter.
7. It naturally explains why the proportions of ordinary matter, dark matter and dark energy in the universe at this moment are of the same order of magnitude in the lamdaCDM model of cosmology (the "coincidence problem").
8. It likewise explains why the apparent cosmological constant is so small (i.e. there actually isn't any dark energy or cosmological constant and the observational evidence is a function of gravitational fields between non-elliptical galaxies being weaker than one would expect because gravitons tend to stay within gravitationally bound galaxies more often than they would if gravitons did not interact with each other).
9. It explains all dark matter phenomena and much if not all dark energy phenomena with a single, widely assumed hypothetical particle beyond the Standard Model, the graviton, without having to hypothesize additional new physics particles or additional fields or extra dimensions that are not observed.
10. It has just one experimentally determined constant (the gravitational coupling constant) rather than the three experimentally determined constants (G, the cosmological constant lambda and one constant related to dark matter such as the dark matter particle mass) of General Relativity with a cosmological constant and cold dark matter. Relativistic MOND theories such as TeVeS also need three (the MOND acceleration constant, G and the cosmological constant).
11. Its mathematical conclusions are well motivated by experimentally confirmed consequences of QCD in circumstances where the gravitational equations and the quantum gravitational equations are similar.
12. The respects in which Deur's approach differs from conventional general relativity (e.g. it localizes gravitational energy, it effectively includes gravitational fields in the stress-energy tensor, it conserves mass-energy, it considers higher order terms that are natural in a graviton formulation) involve issues that have been the subject of considerable scholarly discussion over the last century, while it does realize the Einstein equations as its classical limit for a sufficient set of simplifying assumptions.
13. Unlike other modified gravity and dark matter theories which are generally purely phenomenological, Deur's approach is well motivated theoretically from a fundamental physics perspective.
14. It would not lead to significantly different predictions around time of the Big Bang because the Big Bang is widely assumed to have been spherically symmetric.
15. It would not lead to very different predictions about the properties of black holes which are also widely assumed to be spherically symmetric. In general, in the spherically symmetric limit, which is a good approximation of most situations involving strong gravitational fields, it reduces to General Relativity in a domain where the predictions of General Relativity have been rigorously confirmed.
16. It would not lead to very different predictions at the solar system scale where mass distributions around the Sun are very spherically symmetric and the mass of the total system is very small compared to galaxies.
17. This is the basis of two peer reviewed published articles in respectable journals by a professional physicist. Whether or not it is correct, it is not a crackpot theory. Indeed the author's primary background in QCD, rather than general relativity, may explain why he was able to see mathematical possibilities that others in the seemingly unrelated fields might not, and to appreciate what simplifications of the naively intractable equations could make them workable without sacrificing their accuracy greatly.
18. In this theory it is natural that space-time is extremely close to being topologically flat as is observed.
19. There are serious problems with most dark matter theories and the few that remain viable are close to being overconstrained by the observational evidence.
20. The apparent shortcomings of this approach (failure to explain inflation - although it might if a cosmology on this basis were developed, and failure to explain baryogenesis and leptogenesis) are shared by almost all of its competitors, but unlike those theories it doesn't also have to explain where dark matter comes from as the emission and absorption of gravitons on an ongoing basis over the life of the universe is well explained.
In short, the Standard Model and a Deur type quantum gravity theory involving just one additional tensor boson beyond the Standard Model, suffice to explain all observed phenomena in the Universe, delivering us to the "end of physics" at the fundamental level, except for the very early parts of Big Bang cosmology and the deeper relationships between the component parts of the core theory in some kind of unification of the forces and particles.
Why Deur's approach?
Why is Deur's approach so attractive?
Occam's Razor: it explains more, with a simpler theory, than the alternatives.
1. It can reproduce the flat rotation curves and Tully-Fisher relationship for spiral galaxies recovered in other theories with dark matter and/or modified gravity.
2. More generally, essentially all arguments for modified gravity theories relative to dark matter theories are also arguments in favor of this theory (e.g. the close relationship between luminous matter distributions and dark matter distributions and the low scatter of this relationship, the contrived assumptions necessary to make N-body dark matter simulations work, etc.).
3. It explains why satellite galaxies tend to arrange themselves in a plane of rotation around a galaxy.
4. It explains the variation in the proportion of dark matter amongst elliptical galaxies, which almost all other modified gravity and dark matter particle theories fail to do.
5. Unlike MOND which ceases to be predictive beyond the galactic scale, it correctly predicts the approximate proportion of dark matter in galactic clusters.
6. It can explain the bullet cluster entirely without resort to supplemental dark matter.
7. It naturally explains why the proportions of ordinary matter, dark matter and dark energy in the universe at this moment are of the same order of magnitude in the lamdaCDM model of cosmology (the "coincidence problem").
8. It likewise explains why the apparent cosmological constant is so small (i.e. there actually isn't any dark energy or cosmological constant and the observational evidence is a function of gravitational fields between non-elliptical galaxies being weaker than one would expect because gravitons tend to stay within gravitationally bound galaxies more often than they would if gravitons did not interact with each other).
9. It explains all dark matter phenomena and much if not all dark energy phenomena with a single, widely assumed hypothetical particle beyond the Standard Model, the graviton, without having to hypothesize additional new physics particles or additional fields or extra dimensions that are not observed.
10. It has just one experimentally determined constant (the gravitational coupling constant) rather than the three experimentally determined constants (G, the cosmological constant lambda and one constant related to dark matter such as the dark matter particle mass) of General Relativity with a cosmological constant and cold dark matter. Relativistic MOND theories such as TeVeS also need three (the MOND acceleration constant, G and the cosmological constant).
11. Its mathematical conclusions are well motivated by experimentally confirmed consequences of QCD in circumstances where the gravitational equations and the quantum gravitational equations are similar.
12. The respects in which Deur's approach differs from conventional general relativity (e.g. it localizes gravitational energy, it effectively includes gravitational fields in the stress-energy tensor, it conserves mass-energy, it considers higher order terms that are natural in a graviton formulation) involve issues that have been the subject of considerable scholarly discussion over the last century, while it does realize the Einstein equations as its classical limit for a sufficient set of simplifying assumptions.
13. Unlike other modified gravity and dark matter theories which are generally purely phenomenological, Deur's approach is well motivated theoretically from a fundamental physics perspective.
14. It would not lead to significantly different predictions around time of the Big Bang because the Big Bang is widely assumed to have been spherically symmetric.
15. It would not lead to very different predictions about the properties of black holes which are also widely assumed to be spherically symmetric. In general, in the spherically symmetric limit, which is a good approximation of most situations involving strong gravitational fields, it reduces to General Relativity in a domain where the predictions of General Relativity have been rigorously confirmed.
16. It would not lead to very different predictions at the solar system scale where mass distributions around the Sun are very spherically symmetric and the mass of the total system is very small compared to galaxies.
17. This is the basis of two peer reviewed published articles in respectable journals by a professional physicist. Whether or not it is correct, it is not a crackpot theory. Indeed the author's primary background in QCD, rather than general relativity, may explain why he was able to see mathematical possibilities that others in the seemingly unrelated fields might not, and to appreciate what simplifications of the naively intractable equations could make them workable without sacrificing their accuracy greatly.
18. In this theory it is natural that space-time is extremely close to being topologically flat as is observed.
19. There are serious problems with most dark matter theories and the few that remain viable are close to being overconstrained by the observational evidence.
20. The apparent shortcomings of this approach (failure to explain inflation - although it might if a cosmology on this basis were developed, and failure to explain baryogenesis and leptogenesis) are shared by almost all of its competitors, but unlike those theories it doesn't also have to explain where dark matter comes from as the emission and absorption of gravitons on an ongoing basis over the life of the universe is well explained.
In short, the Standard Model and a Deur type quantum gravity theory involving just one additional tensor boson beyond the Standard Model, suffice to explain all observed phenomena in the Universe, delivering us to the "end of physics" at the fundamental level, except for the very early parts of Big Bang cosmology and the deeper relationships between the component parts of the core theory in some kind of unification of the forces and particles.
How Far Away Is The Center Of The Milky Way?
The supermassive black hole at the center of the Milky Way galaxy, Sagittarius A* is 26,000±1,000 light years from Earth.
We report on the detection in the combined Gaia-DR1/RAVE data of a lack of disk stars in the solar neighbourhood with velocities close to zero angular momentum. We propose that this may be caused by the scattering of stars with very low angular momentum onto chaotic, halo-type orbits when they pass through the Galactic nucleus. We model the effect in a Milky-Way like potential and fit the resulting model directly to the data, finding a likelihood (∼2.7σ) of a dip in the distribution. Using this effect, we can make a dynamical measurement of the Solar rotation velocity around the Galactic center: v⊙=239±9 km s−1. Combined with the measured proper motion of Sgr A∗, this measurement gives a measurement of the distance to the Galactic centre: R0=7.9±0.3 kpc.
Jason A. S. Hunt, Jo Bovy, Raymond G. Carlberg, "Detection of a dearth of stars with zero angular momentum in the solar neighbourhood" (6 Oct 2016).
Thursday, October 6, 2016
When Is A Species A Species?
An interesting new study looks at the question of how different genetically two populations have to be in order to uncontroversially constitute separate species and how similar they must be to uncontroversially constitute different populations of one species, empirically, by looking at the amount of genetic differences between populations where species status is controversial.
Speciation results from the progressive accumulation of mutations that decrease the probability of mating between parental populations, or reduce the fitness of hybrids - the so-called species barriers. The speciation genomic literature, however, is mainly a collection of case studies, each with its own approach and specificities, such that a global view of the gradual process of evolution from one to two species is currently lacking. Of primary importance is the prevalence of gene flow between diverging entities, which is central in most species concepts, and has been widely discussed in recent years.
Here we explore the continuum of speciation thanks to a comparative analysis of genomic data from 61 pairs of populations/species of animals with variable levels of divergence. Gene flow between diverging gene pools is assessed under an Approximate Bayesian Computation (ABC) framework. We show that the intermediate "grey zone" of speciation, in which taxonomy is often controversial, spans from 0.5% to 2% of net synonymous divergence, irrespective of species life-history traits or ecology. Thanks to appropriate modeling of among-loci variation in genetic drift and introgression rate, we clarify the status of the majority of ambiguous cases and uncover a number of cryptic species. Our analysis also reveals the high incidence in animals of semi-isolated species, when some but not all loci are affected by barriers to gene flow, and highlights the intrinsic difficulty, both statistical and conceptual, of delineating species in the grey zone of speciation.Camille Roux, et al., "Shedding light on the grey zone of speciation along a continuum of genomic divergence" (October 5, 2016) (emphasis added).
The open access pre-print is a nice, analytical introduction to the various ways of defining what constitutes a species in biology.
I would welcome the efforts of anyone who could determine this percentage by comparing the Neanderthal and Denisovan genomes, respectively, to modern human genomes (something beyond my technical capacity), as some investigators consider these cases to be ambiguous ones.
What Happened In Bronze Age Armenia?
Davidski at his Eurogenes blog notes an interesting disconnect between ancient DNA from the early Bronze Age in Armenia (a.k.a. the Kura-Araxes culture) and the Middle Late Bronze Age in Armenia.
The early Bronze Age ancient DNA from Armenia is pretty much what you would expect:
Armenia_EBA or Kura-Araxes shows strong affinity to Caucasus populations, particularly those from the Northeast Caucasus. This is very cool, and it makes a lot of sense, because historical linguists and archaeologists generally consider Kura-Araxes people to have been early speakers of Hurrian, an ancient language thought to be closely related to present-day Northeast Caucasian languages.
Hurrian and some languages that were probably related (e.g. Hattic) were the principle languages of Anatolia and the highlands near Mesopotamia before the linguistically Indo-European Hittites came along and conquered essentially all of Anatolia, the Northern Levant and northern Mesopotamia. There is good reason to think that the Minoan language also had linguistic family ties to one or more of the non-Indo-European, pre-Hittite languages of Anatolia.
But, the Middle Late Bronze Age Armenian ancient DNA unexpectedly has strong affinities to modern day Latvian and Swedish populations. What contemporary populations could have led to these affinities in the Middle Bronze Age?
Following some statistical testing, he finds that this new component of their ancestry "may have also been closely related to the Sintashta people of the Middle Bronze Age Ural steppes, who do appear very Northern European in terms of genome-wide genetic structure. The time frame fits, so does the expansive and militaristic nature of the Sintashta Culture (see here)." His analysis finds that the Middle Bronze Age Armenians had about 20% Sintashta ancestry with the other 80% from the earlier Early Bronze Age population of the region. The link in his post recounts some of the pertinent information from a new book on the topic by David Anthony (citations in the text omitted in the quotation below):
The violent and transformative Sintashta period, 2100 to 1800 BC, saw the concentration of dispersed MBA mobile herder populations into MBA II fortified settlements east of the Urals, and this settled Sintashta phase ushered in the settled Petrovka-Alakul economy as well as the artifact and grave types of the early LBA Andronovo horizon....Sintashta-Petrovka chariot-driving chiefs contacted the irrigated civilizations of Central Asia (Bactria-Margiana Archaeological Complex [BMAC]), shown at the Petrovka settlement of Tugai near Sarazm and Petrovka-style ceramics inside the walled BMAC town of Gonur. Perhaps Ural copper and steppe horses were exchanged for Asian luxury goods (textiles?) for distribution to local steppe allies. The geographic expansion of Petrovka-style sites from the southeastern Ural steppes into the Zeravshan Valley in Central Asia was the foundation for the later development of Andronovo styles across Kazakhstan....After the formation of the almost pan-continental Srubnaya-Andronovo cultural horizon, beginning around 1900 to 1800 BC, innovations that included bronze casting, chariotry, and some aspects of pastoral subsistence and settlement types began to diffuse between regions that had formerly appeared materially isolated, encouraging the movement of commodities such as copper, tin, and horses and enabling the more patchy diffusion of cultural traits, including language, rituals, and packages of distinctive elite behaviors. At its eastern end, the Andronovo network interacted across the Tien Shan with what is today northwestern China during the rise of the earliest Chinese state in the late Quijia, Erlitou, and early Shang periods and with Central Asia during the declining centuries (1800–1600 BC) of the BMAC and Namazga VI cultures.
The Sintashta culture population's ancient DNA as a source for the Middle Bronze Age demographic shift in Armenia is preferred in statistical comparisons relative to other candidate populations which he labels Potapovka, Corded Ware from Central Europe, Poltavka, Andronovo and Srubnaya populations.
This part of the world was not literate in this era, so there is no historical record of a major invasion or conquest as far as Armenia by chariot driving warriors from the Ural Steppes, and there isn't really any strong archaeological pointer to this significant population upheaval. But, the ancient DNA evidence and what we do know about the archaeological cultures in existence at the time certainly supports Davidski's inference.
This also suggests that one of the reasons that people in the Caucasus mountains look more Northern European than you would expect, for example, from comparing them to nearby Iranians, is that a significant share of them received a significant infusion of Northern European ancestry in the Middle Bronze Age.
This Middle Bronze Age event would also be a plausible historical moment for a language shift from Hurrian or a related language to an Indo-European language such as an early version of the Indo-European Armenian language.
This Middle Bronze Age event would also be a plausible historical moment for a language shift from Hurrian or a related language to an Indo-European language such as an early version of the Indo-European Armenian language.
Tuesday, October 4, 2016
Do We Still Need Barbarians?
Much of the larger sweep of history can be summed up in a pretty simple dynamic.
When conditions, which are mostly a function of climate, are favorable, civilized settled societies thrive and can keep "barbarians" (historically mostly herders as opposed to more settled farmers) at bay.
When conditions are unfavorable, often again as a function of climate, barbarians rush in and destroy the settled society because their culture is better adapted to adverse environmental conditions, but they either retreat or acclimate to a settled lifestyle as conditions improve again.
Rinse and repeat.
The question then is whether this dialectic is still relevant, or whether we are at "the end of history" at which point the barbarians have grown obsolete.
In a war of competing cultures model, the fierce cultures of honor, globally often Muslim, domestically often Evangelical Christian, have a great deal in common with the barbarians of old. And, we are almost certainly entering an era in which climate conditions will be less favorable for most of humanity.
We would expect a shift in selective fitness in favor of "barbarian cultures" relative to "civilized cultures" as a result. But, perhaps the technologies which civilized cultures are more suited to nurturing has become so decisive that this overcomes the benefits of cultural norms more naturally suited to a survival/adversity mode.
Accuracy of Charged Pion Mass Measurement Improved
The Particle Data Group value for the mass of the charged pion has a precision of ± 2.5 parts per million. A new experiment has improved the precision of the charged pion mass measurement by almost 50% to ± 1.3 part per million.
The newly measured value of the charged pion which is more accurate than any previous measurement to date is 139.57077±0.00018 MeV/c^2. Put another way, this is a more or less perfect measurement to the nearest 1000 electron volts/c^2, and is between 1,000 and 10,000 times more precise than the experimental precision of a typical newly discovered hadron.
This experimentally measured value is more than a thousand times more precise than the theoretical value that can be determined from first principles using QCD in the Standard Model, even though, in principle, the Standard Model with sufficiently accurately measured physical constants contains everything needed to determine this mass to this level of precision and more.
Our experimental measurements of the charged pion mass matched the precision of our current theoretical prediction of the charged pion mass in the year 1954 (62 years ago).
(This is also a good point to make a general observation about particle physics. Many measurements in particle physics are of fundamental or composite particles which are perfectly interchangeable parts which once measured accurately never need to be measured again. If you do dozens of different experiments that measure the mass of a charged pion to this level of precision, you will get a distribution of results will that is consistent with a Gaussian distribution with a mean close to the true value of the charged pion mass and a standard deviation with a 1 part per million margin of error. The true value is going to be the same every time even at this immense level of precision which rivals that of pretty much any precision piece of equipment ever made by man.)
Why is the theoretically calculated value so much less precise?
One immediate source of this limitation is that the quark masses and strong force coupling constant aren't known to sufficient precision. But, the deeper source of the lack of precision is that we lack the computational power to determine the formula into which the constants would be added to a sufficient number of terms to provide the required theoretical accuracy.
What would be possible if we could calculate a greater number of terms in the relevant QCD formulas?
If we could calculate the formula out to enough terms to make the theoretical error small enough, we could compare the half dozen or dozen most accurately measured hadron masses (such as the charged pion, proton and neutron) to the experimentally measured results and use them to determine the masses of the light quarks and the strong force coupling constant to comparable degrees of precision. We could then use those constants in turn to determine with masses of the heavier quarks with more precision by using the most accurately measured masses of hadrons containing heavy quarks and the newly determined more accurate constants.
More accurate knowledge of those physical constants, in turn, would allow us to make far more accurate predictions of all forms of QCD processes (e.g. particle decays and scattering processes at high energies). And, more accurate measurements of physical constants would also provide a more meaningful test of hypothetical mathematical relationships between those physical constants which could elucidate the deeper theory that gives rise to the Standard Model's physical constants.
Why is this approach attractive as an area to spend fundamental physics research funds?
The most attractive thing about this avenue of research, despite its somewhat dry nature, is that we have exact rules telling us how to calculate the relevant formulas in QCD to any desired degree of precision, so this approach is guaranteed to produce more accurate knowledge of Standard Model constants and the associated advances in science, even if we never do another measurement of a QCD observable ever again. It would even allow us to reanalyze past QCD observations in a manner that would increase their precision as well.
Right now, it can take many months to several years with super-computers to come up with a formula necessary to get even four or five digit precision in the result. But, for the most part, the time it takes to come up with the answer is scalable with increased computer power.
In other words, if we spent $5 billion on computers to do QCD calculations instead of $500 million today (these are purely hypothetical numbers, I don't know how much we actually spend right now on computers to do QCD calculations), we could do calculations that now take 5 years in 6 months, and could do calculations that would take 50 years to do now in a much more tolerable 5 years, increasing the precision of the formula significantly.
There aren't many areas of physics where you can pretty much guarantee scientific advances just by spending more money on more and more powerful computers. But, QCD and by association, the whole of Standard Model fundamental physics, is one area where spending more money in this way can guarantee scientific advances.
Monday, October 3, 2016
Marijuana and Hops Were Cultivated In 4th Century BCE Madagascar
Established dates show definite human agricultural activity [in Madagascar] during the 5th century BC, with Cannabis and Humulus (Hops) visible in palynology assemblages.From here relying on [1] (a source which cites a 4th century BCE date rather than a 5th century BCE date).
The 4th century BCE pre-dates the usually hypothesized dates at which the first Austronesians arrived (about 500-1000 years later), although it isn't clear if the previous population was viable enough to last until then. The previous population apparently had less ecological impact on the island than the Austronesians and little genetic impact on the subsequent population which was a mix of Austronesians (ultimately originating in Borneo) and East Africans.
This is mind-blowing because the usual interpretation of the pre-Austronesian population of Madgascar is that it was made up of people who unintentionally ended up there after being cast about in a storm who regressed from a possibly agriculturalist or herder origins to a foraging lifestyle. But, cultivation of these crops, neither of which is native to Madagascar, would suggest either an intentional colonization effort by nearby Africans from the coast for which there is no other archaeological evidence of long distance maritime trade, or perhaps by Yemeni and Somalian sea farers who were the first to conduct long time maritime trade in the Indian Ocean, mostly on a circuit that linked Mesopotamia with the Indus River Valley civilization with the Ethiopian coast.
This is mind-blowing because the usual interpretation of the pre-Austronesian population of Madgascar is that it was made up of people who unintentionally ended up there after being cast about in a storm who regressed from a possibly agriculturalist or herder origins to a foraging lifestyle. But, cultivation of these crops, neither of which is native to Madagascar, would suggest either an intentional colonization effort by nearby Africans from the coast for which there is no other archaeological evidence of long distance maritime trade, or perhaps by Yemeni and Somalian sea farers who were the first to conduct long time maritime trade in the Indian Ocean, mostly on a circuit that linked Mesopotamia with the Indus River Valley civilization with the Ethiopian coast.
In a related development, a recent paper on archaeobotany notes that Austronesians also settled the island of Comoros (which lies between East Africa and Madagascar) and probably settled it before they settled Madagascar.
Incidentally, palynology is a discipline whose most common activity according to a Google definition (the boundaries are the subject of ongoing disciplinary turf wars), is the study of pollen grains and spores, especially as found in archaeological or geological deposits.
[1] Burney, D. A; et al., "A chronology for late prehistoric Madagascar" Journal of Human Evolution. 47. pp.25- 63 (2004).
Baryogenesis And The Matter-Energy Balance Of The Universe
Estimating A Mass-Energy Mix From Rest Mass Loss In The Decay Of Democratically Created Quarks
One of the main focuses of scientists researching cosmology and fundamental physics is the matter-antimatter asymmetry of the quarks and charged leptons of the universe, almost all of which are matter rather than antimatter.
But, put that issue aside for a moment and assume that we know how the baryon number of the universe came to be something on the order of 10^54 when the laws of physics at every scale we have been able to measure them provide that baryon number is conserved.
Let's think about another issue: the relative amounts of ordinary matter and other stuff in the total mass-energy budget of the universe, which according to the standard model of cosmology is roughly 5% ordinary matter, 26% dark matter and 69% dark energy, give or take a little depending upon which set of experimental data you use to determine its parameters.
Now, there are several boson interactions in the Standard Model that can produce quarks. They can be produced in W and Z boson decays, in which case the products a "democratic" between quark flavors (although quarks are favored over leptons 3-1 because each color of quark is treated as distinct in this "democracy"), subject to conservation of mass-energy concerns. They can be produced by pairs of photons, also democratically, subject to conservation of mass-energy concerns. They can be produced by gluon fusion, again democratically, subject to conservation of mass-energy concerns. Or, they can be produced by Higgs boson decays, proportionate to rest mass and subject to conservation of mass-energy concerns.
The early universe is widely assumed to have been essentially maximal in terms of available mass-energy, so a large share of the quarks that were not cancelled out in matter-antimatter annihilations would be top, bottom, charm or strange quarks, but would swiftly decay to a mix of up and down quarks.
In those decays, the vast majority of the rest masses of these second and third generation quarks would be converted into something other than quarks, since no new net quarks could be created. And, it is straight forward to model the amount of energy emitted in this fashion relative to the current count of up and down quarks in the universe today, with a variety of assumptions about the mix of quark production methods and the amount of time elapsed during periods when some but not all quark flavors could be generated consistent with mass-energy conservation.
For example, using the assumption that all quarks were initially created in equal proportions, calculating their rest masses, and subtracting the mass (from quarks and gluons) of all baryons in existence today, you end up with a back of napkin estimate that baryons should make up about 1% of the mass-energy of the universe today. (I'll leave this straight forward naive calculation using PDG values as an exercise for the reader.)
Other Implications
Reconciling this to the 5% of mass-energy in the standard model of cosmology today takes a couple of steps. First, you would have to add in adjustments for radiation (i.e. photons) and neutrinos, both of which are numerically small and don't make a lot of difference. Second, you would have to make an adjustment for the aggregate kinetic energy and energy from angular momentum of the universe, for which the standard model of cosmology also makes no adjustment which might be fairly significant.
Suppose, for sake of argument, that this gives baryons 3% of the mass-energy of the universe, which is still three times our naive estimate of 1%. This would imply that one-third of the initial mass-energy of the universe as of the time that conservation of mass-energy began to apply, went into creating quarks, while the balance went into leptogenesis (to which a similar analysis could be applied if we knew the ratio of neutrinos to antineutrinos in the universe, which we don't) and to the creation of fermion-antifermion pairs that annhilated and to the creation of bosons which lack baryon or lepton number.
This one-third fraction would also let us know how strongly CP would have to be violated in the early universe to create the existing baryon number of the universe.
Some Other Caveats
Now, one problem with this is that general relativity does not conserve mass-energy, for example, creating it with the cosmological constant as the universe expands, and destroying it via the gravitational red shifting of photons, unless there is a quantity of gravitational potential energy which is conserved and balances gravitational changes in mass-energy. Physicists differ regarding whether this is a proper thing to consider.
But, this does not itself imply that the analysis above is pointless even if general relativity does not conserve mass-energy. If the universe does start to obey conservation of baryon number at some point, and not all quarks in the universe of up and down quarks at that point, the difference between the mass at that point and the mass of up and down quarks in the end state mere minutes later, must end up in creating mass-energy of some other type. This is true whether or not general relativity conserves mass-energy and continues to be a source for other constants of the standard model of cosmology.
But, this does not itself imply that the analysis above is pointless even if general relativity does not conserve mass-energy. If the universe does start to obey conservation of baryon number at some point, and not all quarks in the universe of up and down quarks at that point, the difference between the mass at that point and the mass of up and down quarks in the end state mere minutes later, must end up in creating mass-energy of some other type. This is true whether or not general relativity conserves mass-energy and continues to be a source for other constants of the standard model of cosmology.
There are also subtle issues with determining total kinetic energy and total energy from angular momentum in the universe, in part, from the fact that kinetic energy is usually frame of reference dependent while general relativity is background independent, and in part from the fact that gravitational lensing estimates of the mass of galaxies and galactic clusters ought to automatically include the gravitational mass equivalent attributable to the angular momentum and internal kinetic energy of those systems. An effort to estimate it is found here. A similar March 2014 paper by the same author is found here.
Thirdly, a less naive calculation would have to consider the fact that the masses of quarks in high energy circumstances are different from the masses of quarks in today's low energy circumstances, because quark masses, like many other Standard Model of particle physics physical constants, run with energy scale. In general, if I recall correctly, the running of the quark masses tends to make them lighter at higher energy scales and heavier at lower energy scales.
Fourth, this analysis assumes that baryongenesis begins after the laws of physics start to conserve baryon number. But, it is also perfectly possible that quarks are created and have already begun to decay in earnest before conservation of baryon number holds true, in which case the analysis above will overstate the amount of energy created by quark decay after baryon number conservation applies.
For example, another interpretation of baryons making up 3% of the mass energy of the universe would be that baryon number conservation didn't begin to apply until a large share of the quarks created in the universe had already decayed, so that a disproportionate number of the quarks in existence when baryon number conservation began to apply were not heavy quarks. Indeed, this cutoff would merely need to happen sometime between a time that was energy rich enough for top quarks to be one-sixth of all quarks created and a time when the universe was not energy rich enough to create bottom quarks.
This could be a feature rather than a flaw as well, however, because if we apply whatever assumptions we determine are necessary to get the numbers to work for baryogenesis, and then apply the same assumptions to leptogenesis, we might very well be able to make both an untestable prediction of the energy content of the universe attributable to lepton decay, and a testable prediction (in principle, at least) regarding the currently unknown total lepton number of the universe (which would not necessarily be the same as the baryon number of the universe, as most GUT models assume, in this analysis). This could be tested as soon as the ratio of neutrinos to antineutrinos in the universe could be measured to any meaningful precision (even plus or minus 10% accuracy would rule out all sorts of leptogenesis theories and favor others).
But, the fact that a very naive back of napkin estimate of the amount of ordinary mass in the universe based upon the loss of rest mass from quark decay and the conservation of baryon number is of the right order of magnitude, and that some of the adjustments required to make that estimate less naive (such as considering the total kinetic energy and energy from angular momentum in the universe and adjusting quark masses for energy scale) suggest that this kind of analysis isn't entirely off the mark as a useful line of inquiry about the cosmology of the very early universe.
Disclaimer
This analysis, other than the general principles of it, are my personal conjecture and are not supported by any literature in the field done by professionals considering the question in this manner that I have read. So, please do not take these conjectures as established scientific facts.
But, on the other hand, I do not claim to be the first person to come up with this analysis which is fairly obvious to anyone in the field, and due to the caveats I mention or some other reason, it could be that there is good cause why this doesn't work that is more obvious to professionals in the field which is why it isn't considered. But, I have not reviewed the literature sufficiently to know if this idea is original or not (only that it is not the subject of much active publishing and investigation in the last few years) and honestly, I don't know that I would have the competence to do such a comprehensive literature search in a manner well calculated to find previous articulations of this idea as a previous investigator might have used different terminology to describe the key concepts than I do.
Friday, September 30, 2016
Pre-Industrial Societies Reward High Status Men With More Children
From the hunter-gatherer era and on into societies based on herding and farming, high social status men have significantly more children than low social status men. Then, in the industrial era, that relationship was inverted. That is the conclusion of a new meta-analysis of 33 pre-industrial societies.
I've seen a study along the same lines out of a University of Michigan scholar a decade or two ago, that looked at historical and legendary history documents to show the gradually decreasing number of mates and children of ultra high status men from the Bronze Age through the present, with significant changes continuing even from the Victorian era to the 20th century. The drivers of this change aren't entirely clear.
The study and its abstract are as follows:
Social status motivates much of human behavior. However, status may have been a relatively weak target of selection for much of human evolution if ancestral foragers tended to be more egalitarian. We test the “egalitarianism hypothesis” that status has a significantly smaller effect on reproductive success (RS) in foragers compared with nonforagers. We also test between alternative male reproductive strategies, in particular whether reproductive benefits of status are due to lower offspring mortality (parental investment) or increased fertility (mating effort). We performed a phylogenetic multilevel metaanalysis of 288 statistical associations between measures of male status (physical formidability, hunting ability, material wealth, political influence) and RS (mating success, wife quality, fertility, offspring mortality, and number of surviving offspring) from 46 studies in 33 nonindustrial societies. We found a significant overall effect of status on RS (r = 0.19), though this effect was significantly lower than for nonhuman primates (r = 0.80). There was substantial variation due to marriage system and measure of RS, in particular status associated with offspring mortality only in polygynous societies (r = −0.08), and with wife quality only in monogamous societies (r = 0.15). However, the effects of status on RS did not differ significantly by status measure or subsistence type: foraging, horticulture, pastoralism, and agriculture. These results suggest that traits that facilitate status acquisition were not subject to substantially greater selection with domestication of plants and animals, and are part of reproductive strategies that enhance fertility more than offspring well-being.
Christopher R. von Rueden, Adrian V. Jaeggi. "Men’s status and reproductive success in 33 nonindustrial societies: Effects of subsistence, marriage system, and reproductive strategy." 113 (39) Proceedings of the National Academy of Sciences 10824 (2016).
Hominin Evolution Triggered By Climate Change
What did hominins like humans and their archaic hominin ancestors evolve?
One important factor was a major wave of global cooling from 7 million years ago that created the Savannah ecosystems that our ancestors evolved to fill.
The time period during which this happened is known as the late Miocene Epoch.Around 7 million years ago, landscapes and ecosystems across the world began changing dramatically. Subtropical regions dried out and the Sahara Desert formed in Africa. Rain forests receded and were replaced by the vast savannas and grasslands that persist today in North and South America, Africa and Asia.Up to now, these events have generally been explained by separate tectonic events -- the uplift of mountain ranges or the alteration of ocean basins -- causing discrete and local changes in climate. But in a new study, a team of researchers has shown that these environmental changes coincided with a previously undocumented period of global cooling, which was likely driven by a sharp reduction in atmospheric carbon dioxide.
The paper spelling all of this out is:
Timothy D. Herbert, Kira T. Lawrence, Alexandrina Tzanova, Laura Cleaveland Peterson, Rocio Caballero-Gill, Christopher S. Kelly. "Late Miocene global cooling and the rise of modern ecosystems." Nature Geoscience (2016)
Gamma Ray Bursts Probably Won't Wipe Us Out, But They Could
Every once and a while a huge gamma ray burst from space strikes a planet. If the planet is like Earth and the gamma ray burst is severe enough, this kills the ozone layer from the outside and everything dies, because the biosphere on the planet is no longer protected from cosmic rays.
Fortunately, about 65% of gamma ray bursts are survivable for planets like Earth. Also, they aren't terribly likely to hit planets way out on the fringe of a galaxy, like ours, as opposed to planets in the inner galaxies where the higher density of stars and a complicated confluence of other considerations related to the age and metal composition of the stars involved make gamma ray bursts more common.
So, bottom line:
The bad news is that I have just informed you of a new existential threat to all life on Earth that you'd probably never considered or worried about until now. But, the good news is that this particular threat is probably less likely to kill us all than all sorts of other potential threats from space like large heavy objects crashing into the planet, or the Sun expanding and frying the planet, or space aliens invading us. So, really, it's no big thing.
A planet having protective ozone within the collimated beam of a Gamma Ray Burst (GRB) may suffer ozone depletion, potentially causing a mass extinction event to existing life on a planet's surface and oceans. We model the dangers of long GRBs to planets in the Milky Way and utilize a static statistical model of the Galaxy that matches major observable properties, such as the inside-out star formation history, metallicity evolution, and 3-dimensional stellar number density distribution. The GRB formation rate is a function of both the star formation history and metallicity; however, the extent to which chemical evolution reduces the GRB rate over time in the Milky Way is still an open question. Therefore, we compare the damaging effects of GRBs to biospheres in the Milky Way using two models. One model generates GRBs as a function of the inside-out star formation history. The other model follows the star formation history, but generates GRB progenitors as a function of metallicity, thereby favoring metal-poor host regions of the Galaxy over time. If the GRB rate only follows the star formation history, the majority of the GRBs occur in the inner Galaxy. However, if GRB progenitors are constrained to low metallicity environments, then GRBs only form in the metal-poor outskirts at recent epochs. Interestingly, over the past 1 Gyr, the surface density of stars (and their corresponding planets) that survive a GRB is still greatest in the inner galaxy in both models. The present day danger of long GRBs to life at the solar radius (R⊙=8 kpc) is low. We find that at least ∼65% of stars survive a GRB over the past 1 Gyr. Furthermore, when the GRB rate was expected to have been enhanced at higher redshifts, such as z≳0.5, our results suggest that a large fraction of planets would have survived these lethal GRB events.
Michael G. Gowanlock, "Astrobiological Effects of Gamma-Ray Bursts in the Milky Way Galaxy" (29 September 2016)
The First Farmers Colonized Europe; The Indo-Europeans Conquered It
Razib Khan sums up a recent paper comparing the gender composition of newcomers to Europe, first among the first wave of farming in the Neolithic era, and then in the major demic upheaval that accompanied the arrival of Indo-Europeans from the Steppe into Europe in the Bronze Age.
The Neolithic populations were gender balanced, probably migrated as families colonizing virgin farmland starting in Anatolia and then to Southeast Europe ca. 8000 years ago and from there West and North, after a formative period during which a Near Eastern population mixed with European hunter-gatherers. But, they didn't admix with local populations much for many centuries until farming hit its first major widespread, but temporary, collapse. Remaining hunter-gatherer populations were at that point enriched in the gene pools during this bottle neck.
The Indo-European migrants from the steppe, ca. 5000 years ago, in contrast, probably came in armed war bands on horses with men outnumbering women in ratios somewhere between 14-1 and 5-1. They took local wives at the expense of local men who were squeeze out of the gene pool by death or simply denial of local women to marry. This process continued for multiple generations, rather than in a single pulse.
Further Back In Time
There were also several waves of migration before the Neolithic Revolution.
Neanderthals were the dominant hominins of Europe from more than 200,000 years ago until about 40,000 years ago (in round numbers). They probably evolved locally from more archaic hominins who migrated to Europe from Africa. Their time period is known as the Lower Paleolithic era.
In round numbers, ca. 40,000 years ago, early modern human hunter-gatherers called Cro-Magnons swept into Europe from the Southeast and largely replaced the Neanderthals who had lived in Europe in smaller number with a hunting style focused more exclusively on large game than the new Cro-Magnon population. This was near the beginning of an era known as the Upper Paleolithic era. At the time the Cro-Magnon people migrated to Europe, modern humans had already been outside Africa from many thousands of years, but presumably because that territory was already taken by the Neanderthals, it took modern humans longer to penetrate Europe.
The Cro-Magnon people had it good for a while, but eventually, the climate cooled and glaciers came to cover most of Northern Europe banishing them to three main refuges, the Franco-Cantabrian one, one in Italy, and one in the Southeastern Mountains, where temperatures were tolerable. This ice age was at its peak roughly 20,000 years ago.
Several thousand years later, the glaciers retreated, the Cro-Magnon people in the refuges repopulated Europe and they were joined by new people from the Near East and North Africa during a time period known as the Mesolithic era. This population that had a few thousand years earlier repopulated Europe was the population of hunter-gatherers who were in Europe when the first farmers of the Neolithic Revolution arrived.
1000 Posts
This is the 1000th post at Dispatches From Turtle Island, which has maintained its rather quirky mix of about 50% physics (508 posts out of 1000) and about 50% anthropology and genetics for the roughly five years that it has been in existence.
As of the time I am writing this post, there have been 1876 published comments (excluding deleted comments), which is an average of almost two comments per substantive post.
There have been 391,729 page views of this blog since its inception, an average of 392 page views per post, although that average is highly skewed by a few posts that have received very high traffic, such as the all time most visited post on this blog about "Pre-Out of Africa Population Sizes and Densities", which has received 12,707 page views.
This blog gets less traffic than its sister blog, Wash Park Prophet, from which it was split off. But, the quality and sophistication of the readership is quite impressive.
As of the time I am writing this post, there have been 1876 published comments (excluding deleted comments), which is an average of almost two comments per substantive post.
There have been 391,729 page views of this blog since its inception, an average of 392 page views per post, although that average is highly skewed by a few posts that have received very high traffic, such as the all time most visited post on this blog about "Pre-Out of Africa Population Sizes and Densities", which has received 12,707 page views.
This blog gets less traffic than its sister blog, Wash Park Prophet, from which it was split off. But, the quality and sophistication of the readership is quite impressive.
Elk Migrations To North America
I missed this interesting study at the time it was originally released. It uses multiple methods to infer the arrival of elk in North America via Beringia which generally coincides with the human migration to North America via essentially the same route at about the same time.
Human colonization of the New World is generally believed to have entailed migrations from Siberia across the Bering isthmus. However, the limited archaeological record of these migrations means that details of the timing, cause and rate remain cryptic.
Here, we have used a combination of ancient DNA, 14C dating, hydrogen and oxygen isotopes, and collagen sequencing to explore the colonization history of one of the few other large mammals to have successfully migrated into the Americas at this time: the North American elk (Cervus elaphus canadensis), also known as wapiti.
We identify a long-term occupation of northeast Siberia, far beyond the species’s current Old World distribution. Migration into North America occurred at the end of the last glaciation, while the northeast Siberian source population became extinct only within the last 500 years. This finding is congruent with a similar proposed delay in human colonization, inferred from modern human mitochondrial DNA, and suggestions that the Bering isthmus was not traversable during parts of the Late Pleistocene. Our data imply a fundamental constraint in crossing Beringia, placing limits on the age and mode of human settlement in the Americas, and further establish the utility of ancient DNA in palaeontological investigations of species histories.
Meirav Meiri, et al., "Faunal record identifies Bering isthmus conditions as constraint to end-Pleistocene migration to the New World", Proceedings of the Royal Society B: Biological Sciences (December 11, 2013) (Hat tip to Linear Population Model).
Thursday, September 29, 2016
What Did Neanderthal Speech Sound Like?
Based upon the physical size and shape of the Neanderthal voice box, nasal cavity, rib cage and thick heavy skull, we can infer that Neanderthal speech was probably loud, and considerably more high pitched and nasal sounding than one might expect, compared to modern human alive today.
Wednesday, September 28, 2016
Calibrating Ancient Egyptian Chronologies
The Thera Eruption Linked Climate Event
An Egyptian inscription made during the reign of the pharaoh Ahmose, the first pharoh of the 18th Dynasty and the New Kingdom in Egypt that followed the Second Intermediary Period of Canaanite, linguistically Semitic Hyskos rule in Egypt "describes rain, darkness and "the sky being in storm without cessation, louder than the cries of the masses".
There is good reason to believe that this was associated with "the result of a massive volcano explosion at Thera, the present-day island of Santorini in the Mediterranean Sea" that was decisive in bringing Minoan civilization to an end. (This is one of two leading candidate as the source for the Atlantis myth, with the other in Southern Iberia.)
Equally important, radiocarbon dating of wood from an olive tree found in the ashes of that eruption provided a reliable date for that eruption: 1621-1605 B.C.E.
With this critical calibration point, it was possible to date Ahmose's reign to considerably earlier than the 1550 B.C.E date previously associated with the start of his reign. And, since Egyptian documents often reckon dates in terms of the reigning monarch, this shifts a huge chunk of the Egyptian historical record about 50+ years earlier, with the events recounted themselves taking place shortly before the beginning of Ahmose's reign.
What does this imply?
Until now, the archeological evidence for the date of the Thera eruption seemed at odds with the radiocarbon dating, explained Oriental Institute postdoctoral scholar Felix Hoeflmayer, who has studied the chronological implications related to the eruption. However, if the date of Ahmose's reign is earlier than previously believed, the resulting shift in chronology "might solve the whole problem," Hoeflmayer said.
The revised dating of Ahmose's reign could mean the dates of other events in the ancient Near East fit together more logically, scholars said. For example, it realigns the dates of important events such as the fall of the power of the Canaanites and the collapse of the Babylonian Empire, said David Schloen, associate professor in the Oriental Institute and Near Eastern Languages&Civilizations on ancient cultures in the Middle East.
"This new information would provide a better understanding of the role of the environment in the development and destruction of empires in the ancient Middle East," he said.
For example, the new chronology helps to explain how Ahmose rose to power and supplanted the Canaanite rulers of Egypt—the Hyksos—according to Schloen. The Thera eruption and resulting tsunami would have destroyed the Hyksos' ports and significantly weakened their sea power.
In addition, the disruption to trade and agriculture caused by the eruption would have undermined the power of the Babylonian Empire and could explain why the Babylonians were unable to fend off an invasion of the Hittites, another ancient culture that flourished in what is now Turkey.
The short term havoc wrecked by this eruption, while it may have weakened the Hyskos rulers of Egypt of the Second Intermediate Period (previously dated from 1650 BCE to 1550 BCE, but now calibrated to 1700 BCE to 1600 BCE) and other regimes in the region, pales next to two major arid periods in the region that bookended this event.
The 4.2 Kiloyear Event
The first, which preceded the Thera eruption from around 2200 BCE to 2000 BCE is called the 4.2 kiloyear event. (This was good news for California which received a two century break from its 6,000 year old megadrought at this time.)
This led to the collapse of Harappan civilization in South Asia (and the disappearance of the Sarasvati River that figures prominently in the Rig Vedic epics), the collapse of the Akkadian Empire in what is now Iraq, and Egypt's First Intermediary period (2231 BCE to 2105 BCE). The First Intermediary Period began with the collapse of Egypt's Old Kingdom (2736 BCE to 2231 BCE), which in turn, was preceded by Egypt's early Dynastic period that started around 3150 BCE according to the new calibration, at the dawn of the Copper Age and some of the earliest moment of written history.
This also weakened the existing Hattic regime in Anatolia, clearing the way for the rise of the Indo-European Hittites, and coincides with the appearance of the first Mycenean Greeks (also Indo-Europeans) in mainland Greece, and the migration of the Tocharians to the Tarim Basin.
This led to the collapse of Harappan civilization in South Asia (and the disappearance of the Sarasvati River that figures prominently in the Rig Vedic epics), the collapse of the Akkadian Empire in what is now Iraq, and Egypt's First Intermediary period (2231 BCE to 2105 BCE). The First Intermediary Period began with the collapse of Egypt's Old Kingdom (2736 BCE to 2231 BCE), which in turn, was preceded by Egypt's early Dynastic period that started around 3150 BCE according to the new calibration, at the dawn of the Copper Age and some of the earliest moment of written history.
This also weakened the existing Hattic regime in Anatolia, clearing the way for the rise of the Indo-European Hittites, and coincides with the appearance of the first Mycenean Greeks (also Indo-Europeans) in mainland Greece, and the migration of the Tocharians to the Tarim Basin.
Bronze Age Collapse
The second, which took place after the Thera eruption, started around 1200 BCE and is commonly known as Bronze Age Collapse.
This brought down the last round of successors to the Bell Beaker culture in Western, Central and Northern Europe. It brought the ethnically Mycenean Greek Philistine Sea people mentioned in the Bible to the Gaza Strip. It led to the fall of the Hittite Empire, and the Trojan War fought on the Western coast of Anatolia. Egypt's Third Intermediate Period starting at the recalibrated date of 1119 BCE, also comes swiftly on the heels of Bronze Age collapse, although it was not the first to fall.
This brought down the last round of successors to the Bell Beaker culture in Western, Central and Northern Europe. It brought the ethnically Mycenean Greek Philistine Sea people mentioned in the Bible to the Gaza Strip. It led to the fall of the Hittite Empire, and the Trojan War fought on the Western coast of Anatolia. Egypt's Third Intermediate Period starting at the recalibrated date of 1119 BCE, also comes swiftly on the heels of Bronze Age collapse, although it was not the first to fall.
Out of the ashes of the Third Intermediate Period comes ancient Egypt's Late Period as an Egyptian dynasty of pharaohs reestablishes itself at a recalibrated date of about 714 BCE (which endures until a recalibrated date of about 382 BCE), right around the time that the Roman Empire and Classical Greece began to reestablish themselves as Iron Age civilizations.
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