The Ten Most Popular Posts Of 2017 (So Far)

The following ten posts were the most popular at this blog in 2017 as measured by page views. Nine were anthropology posts and one (number 2) was a somewhat meta physics posts. Overall, 86 posts in 2017 were on physics (somewhat less than my usual 50-50 split).

South Asia was discussed in two of the anthropology posts, the Americas were discussed in three of them, Africa was discussed in three of them (number 5 is about Africa even though that isn't obvious from the title) although one of the African posts also discusses Europe and the Middle East (number 4), and one was about the Middle East, which is at the intersection of South Asia, Africa and Europe. No posts exclusively about Europe, or about North, East or Southeast Asia, or Oceania (not even Australia) made the cut for the top ten.

10. Dravidian Speaking Gonds In India

9. The Founding Americans Hung Out In Beringia Before Moving South

8. Central African Hunter-Gatherer DNA Is Distinctive

7. Is Poverty Point, Louisiana Evidence Of Complex Social Organization In Hunter-Gathers?

6. The Middle East Really Has Been In The Middle

5. Another Introgressing Hominin Species?

4. The Source Of the Proto-Chadic Y-DNA R1b-V88 People Of Africa

3. Ancient DNA Refined New World Settlement Paradigm

2. Blog Post Results In Revision Of Next Edition Of New Trade Non-Fiction Book!

1. Harappan Y-DNA Leak

With this post, I have also averaged two posts for every three days this year.

Pan European New Year's Traditions

The Old European Culture blog documents some very elaborate New Year's Day traditions in England that have very precise counterparts as far afield as Serbia, Greece and Georgia, suggesting that these traditions may have deep Indo-European roots.

Proton Decay and GUTs

This is a crosspost from Physics Forums about the state of experimental searches for proton decay and the implications of those searches for "grand unified theories" (GUTs) which often predict proton decay.

I see papers on experimental bounds on proton decay every few years or so. The last experimental result I blogged on it was in August of 2015, where I summarized the finding stating with a link to my source that: 

"The Super-Kamiokande Experiment has used an independent method to exclude proton decay and related di-nucleon decays involving protons to charged leptons, neutrinos, photons and neutral and invisible to the experiment's detector's X particles, up to very large mean lifetimes on the order of 10^31 to 10^32 years. 

So, over the life of the universe, the fraction of protons that decay as measured by these methods is less than one per 10^21protons (in words, less than one hundred per gram of protons, and probably less than ten per gram of protons). 

Previous studies using other methods have set a minimum proton lifetime on the order of 10^33 to 10^34 years, i.e. 1.0 to 0.1 such decays per gram of protons over the entire lifetime of the universe, or put another way, less than 1 such decay per 10 kilotons of protons per year (a measurement of truly stunningly great precision). A kiloton of protons is pretty much indistinguishable in mass from a kiloton of hydrogen at this level of precision in measurement."

The latter research results were restated in a 2017 paper considering the DUNE experiment. The Particle Data Group summarizes the experimental literature on proton decay here.  

Another 2015 paper looked at prospects for improving the current limitation with experiments that were in progress. So, anyway, we are probably due for a new experimental result sometime in the next year or two. On the other hand, there has only been a one or two order of magnitude improvement in the experimental exclusion since 1979 when it was about 10^31. 

The experimental exclusion for proton decay is one of the most strict exclusions in the area of experimental tests of the SM, along with baryon number violation and lepton number violation which are also very throughly ruled out to the current limits of experimental precision. But, efforts to further limit the parameter space of these things continues because lots of theories that it would be nice to have be true call for them. 

There is certainly no GUT that works yet, that has been proposed. Papers exploring GUTs are written on a regular basis month in and month out and have been for decades. FWIW, my gross perception from reading a lot of pre-prints without doing a proper statistical analysis is that the most popular directions are minimalist GUTs such as SU(5) and minimal SU(10) GUTs (see also, e.g. SM particles plus a small number of massless scalar bosons and maybe a gravitino) and E8 theories. And, of course, there are always proton decay is just around the corner papers (also here). 

Glashow opined about a year ago that the non-detection of proton decay pretty much ruled out SU(5) unification models which are the most minimalist theoretically possible GUTs. Non-detection of SUSY-GUT particles has also been problematic as there are naive reasons to expect that they should appear not later than 20 TeV and we are now ruling out these particles in the single digit TeV range. 

A prediction for proton decay assuming virtual blackholes as a mediator was made in this 2017 paper. A 2017 paper makes a (funding driving IMHO) argument that proton decay might first start to be discernible in a 100 TeV collider. Another 2017 paper argues that non-detection of proton decay implies strict SUSY parameter space limits. 

A notable 2016 paper explored a mechanism by which a GUT that did not predict proton decay could be realized. Another more recent paper along the same lines is discussed in this thread.

Some Recent Physics Experiment Results

* The ATLAS experiment at the LHC continues to exclude the possibility of light supersymmetric particles.

The search for strongly produced supersymmetric particles decaying into final states with multiple energetic jets and either two leptons (electrons or muons) with the same electric charge or at least three leptons was performed using the proton-proton collision dataset of 36 fb−1 at 13 TeV recorded with the ATLAS detector in 2015 and 2016. Due to the low Standard Model background, these final states are particularly adapted to searches for gluinos or third generation squarks in several supersymmetric production topologies determined from a variety of simplified and phenomenological models. The absence of excess over the Standard Model prediction is interpreted in terms of limits on the masses of superpartners derived at 95% confidence level. In the studied decay modes and depending on the decay topology, the existence of gluinos with masses below 1.9 TeV, sbottoms with masses below 700 GeV, and neutralinos with masses below 1.2 TeV are excluded.

From here.

* Production of a Higgs boson with a top quark pair has been seen with a significance of 4.2 sigma. The results are consistent with the Standard Model prediction.

"An excess of events over the expected background from Standard Model processes is found with an observed significance of 4.1 standard deviations, compared to an expectation of 2.8 standard deviations. The best fit for the tt¯H production cross section is σ(tt¯H)=790+230−210 fb, in agreement with the Standard Model prediction of 507+35−50 fb. The combination of this result with other tt¯H searches from the ATLAS experiment using the Higgs boson decay modes to bb¯, γγ and ZZ∗→4ℓ, has an observed significance of 4.2 standard deviations, compared to an expectation of 3.8 standard deviations. This provides evidence for the tt¯Hproduction model."

From here.

* The Higgs boson observed at the LHC continues to be consistent with the Standard Model Higgs boson according to the ATLAS experiment.

"For a Higgs boson mass of 125 GeV, the ratio of the measured tt¯H signal cross-section to the Standard Model expectation is found to be μ=0.84+0.64−0.61. A value of μ greater than 2.0 is excluded at 95% confidence level while the expected upper limit is μ<1.2 in the absence of a tt¯H signal."

From here.

* As predicted there is still no experimental evidence of magnetic monopoles.

* A current as of 2017 summary of top quark physics can be found in this review article (link to pdf). 

Notably, it explores the definitional difficulties with measuring the top quark mass, which based on the global average by the most precise available means is about 171.9 GeV to 174.3 GeV at plus or minus two sigma in direct measurements, which are consistent with less precise cross-section based measurements. 

The global average width measurement at plus or minus two sigma is 1.11 GeV to 1.79 GeV with a theoretically predicted value for a 172.5 GeV mass top quark of 1.322 GeV.

* There is considerable variety in the properties of the different kinds of filaments of matter that stretch across the universe.

The Great Wall of Syria

In the Bronze Age Syrian farmers in the plain feared barbarian herders from the mountains and took action to defend themselves, analysis of aerial photography and sites on the ground has revealed.

[A] fortified surveillance network over the territory dating from the second millennium (-2,000 to -1,550). It is the first time that such an extensive fortified system has been discovered in the territory. 

This structure, exceptional in its extent and designed to protect urban areas and their hinterlands, is composed of a series of fortresses, small forts, towers, and enclosures that run along the mountainous ridge which dominates the steppes of central Syria. The researchers' work suggests that the fortresses were made from large blocks on unsculpted basalt and formed walls several meters wide and high. In addition, each fortified site was positioned in such a way to ensure that it could see and be seen by others. The spatial organization of this network thus depended on the ability to communicate through light (or smoke) signals in order to rapidly convey information to the major centers of power. The purpose of this regional network would have been to defend the territory, to surveil and protect transport corridors and, above all, to protect the most attractive lands. 

These results consolidate field observations conducted prior to the exploration. These had already enabled the sites to be dated using ceramics collected on site. The access to aerial and satellite observations, from 1960 to the present day, made it possible to reconstruct the network beyond the limits of the zone under exploration. It has thus been identified across a north-south distance of around 150 km.

From Science Daily.

The parallel to the Great Wall of China is obvious. Before the wall was built, China has a similar visual relay.

Another system of similar forts is the source of Britain's "ley lines". Spain also had such a system.

Fantasy fans will also note the similarity to the "Warning beacons of Gondor."

Happy Winter Solstice!

The winter solstice is what inspired the ancients to create monuments and myths. It was the foundation of the discipline of astronomy that still struggles with an ultimate understanding of gravity which, in simplified form, fully explains it with an equation you can fit on a napkin. Today, the winter solstice is merely a footnote, as we are more enlightened, although perhaps also less full of wonder.

The Old European Culture blog in a recent post, seeks to reconcile astronomy, legend and language. A key link: in Sanskrit, the Orion constellation is called the Deer constellation.

Big Cats Have A Common Ancestor 4.5 Million Years Ago

Extant big cats (i.e. lions, tigers, jaguars, leopards and snow leopards) have a common ancestor just 4.5 million years ago, with some branches related more recently (comparable to the depth of hominin diversification). Domestic cats have a common ancestor with big cats about 12 million years ago (comparable to the chimpanzee-hominin divide).

Australian Aboriginal Myth Describes Variable Brightness Stars

Did you know that a few stars that are visible in the night sky vary in brightness over time, in time frames and magnitude of brightness variability that differ from star to star?

Modern astronomers do and ancient Egyptian astronomers did, but in Western European astronomy this wasn't discovered until a few years before the dawn of the 18th century CE, and many ordinary people today don't know this fact. But, Australian aborigines were well aware of it and embedded it in their mythology.

[N]ew research, recently published in The Australian Journal of Anthropology, reveals that Aboriginal oral traditions describe the variable nature of three red-giant stars: Betelgeuse, Aldebaran and Antares.

From here.

The myths not only embed the variable stars in the myths about the constellations that are home to them, but also recount the relative frequency with which their magnitude varies.

More Data Narrows Primordial Black Hole Dark Matter Parameter Space

Black hole merger events detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO) have revived dark matter models based on primordial black holes (PBH) or other massive compact halo objects (MACHO). This macroscopic dark matter paradigm can be distinguished from particle physics models through their gravitational lensing predictions: compact objects cause most lines of sight to be demagnified relative to the mean, with a long tail of higher magnifications. We test the PBH model using the lack of lensing signatures on type Ia supernovae (SNe), modeling the effects of large scale structure, allowing for a non-gaussian model for the intrinsic SNe luminosity distribution and addressing potential systematic errors. Using current JLA (Union) SNe data, we derive bounds ΩPBH/ΩM<0.346(0.405) at 95% confidence, ruling out the hypothesis of MACHO/PBH comprising the totality of the dark matter at 5.01σ(4.28σ) significance. The finite size of SNe limits the validity of the results to M_PBH≳0.01M⊙, fully covering the black hole mergers detected by LIGO and closing that previously open PBH mass range.

Miguel Zumalacarregui and Uros Seljak,"No LIGO MACHO: Primordial Black Holes, Dark Matter and Gravitational Lensing of Type Ia Supernovae"(December 7, 2017).

The limiting minimal size of PBH covered by the exclusion, 0.01M⊙, is equivalent to about ten times the mass of Jupiter (which implies an event horizon of the Primordial Black Hole with a radius of approximately 28 meters, which would fit comfortably within a baseball field).

This is notable, because it makes previous MACHO/PBH exclusions more robust, but the sweet spot for MACHO dark matter was already limited to PBH objects with a mass on the order of the Moon (many hundreds of times less than the mass of Jupiter), and a event horizon radius on the order of millimeters.

Personal Attacks In The Comments Are Strictly Forbidden Here.

This is a warning.

Many blogs in the areas of anthropology and/or physics tolerate some ad hominem (i.e. personal) attacks on other people leaving comments in the comments at their blog, or even make ad hominem attacks in their own posts.

Ad hominem attacks in the comment are completely unacceptable at this blog, and they will be made in original posts here only in very exceptional circumstances.

I am quite willing to tolerate non-mainstream theories and personal conjectures in the comments. And, other commentators are welcome to criticize those theories and conjectures in other comments. But, ad hominem attacks on other people making comments, whether or not they are justified (and sometimes they are), are not permitted here for any reason. 

This is a forum in which a minimum standard civility is imposed.

If you have a criticism of something that someone else has said, you need to figure out how to say that without making it personal (and without making it a racial or ethnic slur or making your point in any otherwise offensive manner).

Northern Chinese Ancient DNA

There is population genetic continuity in Northern China near where the Han Dynasty originated, back to the early Bronze Age (ca. 2000 BCE) according to the ancient DNA that could be extracted from sixty individuals buried a cemetery from that time period. 

Some Southern Central Asians Have About 50% Steppe Ancestry

Davidski at Eurogenes discusses some Southern Central Asian populations in a recent post. This post expands on his rather raw genetic analysis to put his conclusions in historical and anthropological and linguistic context.

Pamiri children via Wipiedia. There are about 350,000 Pamiris in their region, 

who are mostly Shia Muslims

A map showing where Pamiri people live from the same Wikipedia page. 

This region called Badakhshan, is divided between Tajikistan in the north 

and Afghanistan and Pakistan in the south and China's Xinjiang to the west.

Pamiri Tajik Genetics

Davidski demonstrates with convincing autosomal and uniparental genetic evidence that 50% or more of their gene pool is derived from the Pontic Caspian Steppe in Europe (i.e. basically modern Ukraine) with the balance mostly from Iranian farmers and about 8% directly from East Asians. This is consistent with their phenotype, but contrary to the oral history of the origins of their people.

Several South Central Asian populations have a reputation for producing individuals who look surprisingly European, even the lighter shade sort of European from Eastern and Northern Europe. This is especially true of the Pamiri Tajiks, and it's unlikely to be a coincidence, because these people probably do harbor a lot of ancient Eastern European ancestry. 

My own estimates, using various ancestry modeling methods, suggest that Pamiri Tajiks derive ~50% of their genome-wide genetic ancestry from populations closely related to, and probably derived from, Eneolithic/Early Bronze Age pastoralists from the Pontic-Caspian steppe of Eastern Europe, such as the Sredny Stog and Yamnaya peoples.

In his autosomal genetic model he is "using the mostly Yamnaya-derived Iron Age Sarmatians from Pokrovka, Russia, in far Eastern Europe, to illustrate the point. Note that Sarmatians were East Iranic-speakers, which is what Tajiks are."

Many South Central Asian groups, and especially Indo-European-speakers, like the Tajiks, show moderate to high frequencies of two Y-chromosome haplogroups typical of Bronze Age Eastern Europeans: R1a-M417 and R1b-M269. This is old news to the regular visitors here and its implications are obvious, so if you still think that these haplogroups expanded from South Central Asia to Eastern Europe, rather than the other way around, then please update yourself (for some pointers, see here and here). 

And now, courtesy of Peng et al. 2017, we also have a much better understanding of ancient European maternal input into the gene pool of Pamiri groups (see here). The paper doesn't specifically cover the topic of European admixture in South Central Asia, but it nevertheless demonstrates it unequivocally.

In Peng (2017), many mtDNA lineages are: 

shared between Europeans and Central and South Asians; quite a few of these lineages are rooted in Eastern Europe, as shown by both modern-day and ancient DNA, so they strongly imply gene flow, and indeed considerable maternal gene flow, from Eastern Europe deep into Asia. Worthy of note are the lineages belonging to such relatively young (likely post-Neolithic) haplogroups as U5a1a1, U5a1d2b, U5a2a1, and U5b2a1, all of which have already been found in ancient remains from the Pontic-Caspian steppe.

The History of the Pamiri People

The Badakhshan region has had a Silk Road trading based economy attested to with archaeological evidence dating to before 4000 BCE. 

The legendary historical origin story of the Pamiri people, or at least the homegrown dynasty of rulers of Badakhshan, traces the dynasty's origins to the reign of Alexander the Great in the 4th century BCE, although no linguistic or genetic or cultural evidence supports this Iron Age legendary Hellenic history. But, it isn't impossible as the Eastern part of Alexander the Great's empire was a conquered Persian population which may not have involved many Greek and Anatolian migrants below the highest levels of the ruling class and soldiers who did not relocate permanently. It is one of several historical instances where conquerers adopted to a great extent the sophisticated culture of the land they conquered.

Ethnically Persian, local poet and religious scholar Nasir Khusraw led the conversion of the ancestors of the modern Pamiri people to Shia Islam in the 11th century CE.

The kingdom of Badakhshan is historically well attested and flourished from the 15th century CE to 1641 CE, and is mentioned in the Marco Polo story (whose historical accuracy is admittedly sometimes questionable). For the next two centuries, until 1839 CE, the region alternated between conquering outsider Emirs and Khanates, and home grown princes. After that British, Russian and Chinese colonial powers had their way with various parts of the region in succession and not always peacefully. Ultimately today, the region ended up split between Afghanistan and Pakistan (the successors to the British colonial rulers), Tajikistan (successor to Russian and then Soviet colonial rulers), and an autonomous region on the far western frontier of China.

Analysis

At a minimum, Alexander the Great's Iron Age empire, while it may have been one important source of the Iranian Neolithic ancestry of the Pamiri people, which has significant Indo-Iranian steppe admixture itself from sometime in the time frame from ca. 2500 BCE to 1500 BCE or so, was almost surely not the primary source of the substantial and distinctively steppe ancestry found in the Pamiri people relative to Iron Age Iranians.  And the Pamiri apparently also also show little South Asian proper genetic admixture, either in their whole genomes or in their uniparental haplogroups.

This suggests that in the Bronze Age, East Iranian steppe people may have mostly replaced the previous population that had traded there for 1500 to 2000 years or so when these Indo-Europeans arrived.

Part of what makes the ancestry of the Pamiris interesting is that that they have not just autosomal genetic and mtDNA similarity to the Yamnaya people of Ukraine the way the Corded Ware people did, but also significant amounts of Y-DNA R1b-M269 associated with the Southern Steppe, in addition to Y-DNA R1a-M417, associated with the Northern Steppe (which was the predominant Y-DNA haplogroup among both Corded Ware people and people with Indo-Aryan ancestry in South Asia).

Indeed, the fact that the two Y-DNA haplogroups are mixed here, unlike nearby regions adjacent to the steppe, suggests a plausible two step migration, with Y-DNA R1b Yamnaya people forming the first wave that cleared away older populations of the region, and Indo-Iranians (who were predominantly Y-DNA R1a) forming a second wave, perhaps not that many centuries afterwards, who gave the Pamiris their East Iranian language, Y-DNA R1a and an additional dollop of steppe autosomal genetics and steppe mtDNA.

The Y-DNA R1b Yamnaya people, while similar in autosomal genetics and mtDNA to steppe people further north with mostly Y-DNA R1a, whom we can characterize much better linguistically, are almost surely ancestral to Western and Northern European populations where Y-DNA R1b-M269 is predominant. But, the story of their long westward journey and the near disappearance of Y-DNA R1b-M269 men from the steppe they originally inhabited before the Indo-Iranian and Corded Ware expansions as demonstrated by a stark transition in Y-DNA types in ancient DNA in their own homeland is much more of a mystery. 

The linguistic connections between their language(s) the languages spoken in the parts of Europe and Asia where their descendants are now most common is also more obscure. It would be plausible for them to have been linguistically Indo-European, but it isn't a foregone conclusion either, because anthropological and linguistic evidence suggests that the Celtic languages which are the oldest attested languages of the regions where their descendants settled have far to little time depth (1300 BCE or so at most) to have arrived at the same time that the descendants of the Yamnaya people arrived in Western and Northern Europe (ca. 2500 BCE) a dozen centuries earlier.

The Pamiri people are testimony to the fact that the collapsing Yamnaya people had spread to the East on the Silk Road as well as to the West, before or in connection with their collapse.

We don't know if the Y-DNA R1b in the Pamiri is a relict population of a formerly greater Yamnaya range or if it arrives as part of an exodus from Ukraine. But, the fact that they speak an Indo-Iranian language associated with Y-DNA R1a steppe people, denies us much insight in the linguistic character of the Y-DNA R1b steppe people who preceded them, unless substrate influences can be discerned in their East Iranian languages that are not shared by predominantly Y-DNA R1a Indo-Iranian populations.

It would be particularly notable as we try to reconstruct Yamnaya linguistics, if substrate influences found in the Pamiris languages were also shared by Indo-European languages in the Balkans were there is also a mix of Y-DNA R1a and R1b, and in Celtic languages, but was absent in other Balto-Slavic languages and other Indo-Iranian languages. But, those are very fragile ties to establish and doing so is more linguistic art than linguistic science. Alas, in the case of the Pamiris, their historic role as Silk Road traders makes it particularly hard to distinguish substrate influences in their languages from loan words picked up from travelers and fellow Silk Road merchants.