Tuesday, April 30, 2024

Neutron Star Structure Parameter Space

We understand simple systems of Standard Model particles at almost any scale, but the physics of the complex condensed matter system of a neutron star is far less well understood. 

A new study, however, argues that the end product of the analysis of that complex condensed matter system, called its "Equation of State" can be summarized well with just three observable properties of neutron stars. Observation basically confine this parameter space to the portion of the area surrounded by the thick solid black line near the center of the chart below that is not ruled out on other grounds shown. The paper summarizes the evidence supporting these bounds on neutron star parameters.

Numerous models of neutron star (NS) equation of state (EoS) exist based on different superdense-matter physics approaches. Nevertheless, some NS properties show universal (EoS-independent) relations. Here, we propose a novel class of such universalities. Despite different physics inputs, a wide class of realistic nucleonic, hyperonic, and hybrid EoS models can be accurately described using only three parameters. For a given EoS, these are the mass and radius of the maximum-mass NS (or pressure and density in its center) and the radius of a half-maximum-mass star. With such a parametrization, we build universal analytic expressions for mass-radius and pressure-density relations. They form a semi-analytic mapping from the mass-radius relation to the EoS in NS cores (the so-called inverse Oppenheimer-Volkoff mapping). This mapping simplifies the process of inferring the EoS from observations of NS masses and radii. Applying it to current NS observations we set new limits on the high end of the EoS.
Dmitry D. Ofengeim, Peter S. Shternin, Tsvi Piran, "A three-parameter characterization of neutron stars' mass-radius relation and equation of state" arXiv:2404.17647 (April 26, 2024). The body text clarifies that:
One of the most intriguing problems of modern physics is to unveil the mystery of the neutron star (NS) equation of state (EoS, pressure P − density ρ relation). One of the few ways to study it is to measure NS masses M andradii R. As the star is in hydrostatic equilibrium, its EoS determines the M − R relation. Inverting this relation, we can find the EoS. Non-rotating NS hydrostatics is described by the Tolman-Oppenheimer-Volkoff (TOV) equations. The Oppenheimer-Volkoff (OV) mapping from the P − ρ to M − R is a bijection, i.e., there exists inverse OV mapping (IOVM). Thus unambiguous finding of EoS from M and R observations is, in principle, possible. Additionally, a maximum-mass NS (MMNS) exists regardless of the EoS model used. The MMNS characteristics, such as mass Mtov, radius Rtov, pressure Ptov, density ρtov in the center, etc., are specific for a given EoS. 

While the true NS EoS is unique, there are hundreds of various theoretical EoS models present in the literature. Each yields its own M −R, M — central ρ and P relations and, in particular, its own Mtov, Rtov, ρtov, and Ptov. Nevertheless, it has been known for a long time that some relations between various NS properties are universal across the EoS manifold. Some of these relations, like the I-Love-Q relation, originate from a unifying ability of relativistic gravity and are very accurate for almost all existing models of EoS. Others are less precise and exist due to some common features of a subclass of EoSs, which are considered to be “realistic”.

The one-dimensional 68% credible intervals for the key parameters of the approximations (1)— (4) are[:]

M(tov) = 2.28+0.05 −0.06 M⊙

R(tov) = 11.2+0.4 −0.3 km

R(1/2) = 12.0+0.4 −0.3 km

ρ(tov) = 7.7+0.6 −0.3 ρ0, and 

P(tov) = 3.5+1.0 −0.4 ρ0c2.

The boundaries on the maximum neutron star mass are known with roughly ± 2% precision, and the maximum and half-maximum mass neutron star radii are known with roughly ± 4% precision. 

Monday, April 29, 2024

Substrate Languages In Europe

Here's an interesting map of substrate languages in Europe. I don't vouch for its complete accuracy.

Thursday, April 25, 2024

Uralic And Yeniseian Origins

New ancient DNA data informs both that origins of the Siberian Yeniseian peoples, the Native American populations of North America, and the Uralic people. 

In Siberia, two genetically distinct populations emerged from admixture between the early Northeastern Siberian population that was a major source of Native American ancestry, and "groups from Inland East Asia and the Amur River Basin."

One of these populations, the Cis-Baikal Late Neolithic–Bronze Age, was ancestral to the Yeniseian peoples of Siberia, who in turn admixed with some other Northeast Asian and North Central Asia populations.

The other of these populations, the Yakutian Late Neolithic–Bronze Age, was the proto-Uralic population. They spread from an east Siberian origin ca. 2500 BCE, along with subclades of Y-chromosome haplogroup N occurring at high frequencies among present-day Uralic speakers, into Western and Central Siberia in communities associated with Seima-Turbino metallurgy, a suite of advanced bronze casting techniques that starteds to expand rapidly ca. 2000 BCE. As they expanded they admixed with many other people in the region, including Indo-Iranians and various hunter-gather peoples.
The North Eurasian forest and forest-steppe zones have sustained millennia of sociocultural connections among northern peoples. We present genome-wide ancient DNA data for 181 individuals from this region spanning the Mesolithic, Neolithic and Bronze Age
We find that Early to Mid-Holocene hunter-gatherer populations from across the southern forest and forest-steppes of Northern Eurasia can be characterized by a continuous gradient of ancestry that remained stable for millennia, ranging from fully West Eurasian in the Baltic region to fully East Asian in the Transbaikal region
In contrast, cotemporaneous groups in far Northeast Siberia were genetically distinct, retaining high levels of continuity from a population that was the primary source of ancestry for Native Americans. By the mid-Holocene, admixture between this early Northeastern Siberian population and groups from Inland East Asia and the Amur River Basin produced two distinctive populations in eastern Siberia that played an important role in the genetic formation of later people. 
Ancestry from the first population, Cis-Baikal Late Neolithic–Bronze Age (Cisbaikal_LNBA), is found substantially only among Yeniseian-speaking groups and those known to have admixed with them.

Ancestry from the second, Yakutian Late Neolithic–Bronze Age (Yakutia_LNBA), is strongly associated with present-day Uralic speakers. We show how Yakutia_LNBA ancestry spread from an east Siberian origin ∼4.5kya, along with subclades of Y-chromosome haplogroup N occurring at high frequencies among present-day Uralic speakers, into Western and Central Siberia in communities associated with Seima-Turbino metallurgy: a suite of advanced bronze casting techniques that spread explosively across an enormous region of Northern Eurasia ∼4.0kya. However, the ancestry of the 16 Seima-Turbino-period individuals—the first reported from sites with this metallurgy—was otherwise extraordinarily diverse, with partial descent from Indo-Iranian-speaking pastoralists and multiple hunter-gatherer populations from widely separated regions of Eurasia
Our results provide support for theories suggesting that early Uralic speakers at the beginning of their westward dispersal where involved in the expansion of Seima-Turbino metallurgical traditions, and suggests that both cultural transmission and migration were important in the spread of Seima-Turbino material culture.

Sophisticated Science Denial

For those of you who aren't Young Earth Creationists (as about 0.1% of scientists and 46% of American adults are) or Flat Earthers (as essentially no scientists and 10% of American adults are), but still want to ignore consensus physics with lots of independent sources of high precision observational evidence to back it up, this more sophisticated form of science denial, that only rolls back scientific knowledge by about 120 years, may be for you.

As an aside, note that denying that space-time is non-Euclidian, a broad, theory independent observation, is a considerably stronger form of science denial than the mere scientific field of inquiry into whether General Relativity, as formulated by Einstein more than a century ago, is precisely the correct set of equations or is only a very close approximation of reality that is subtly wrong (e.g., because it is classical rather than quantum). The latter doesn't deny scientific evidence. It merely explores the full range of the possible within the constraints of what we know from experiments and scientific observations.

The percentage of the general adult public in the United States who understands that space-time itself is non-Euclidian is probably pretty low. My high, probably overoptimistic, estimate would be that 10-20% of American adults (i.e. about half of four year college graduates plus or minus) understand this fact. I make this estimate even though non-Euclidian geometry is part of the standard high school math curriculum for college bound students, and high school geometry textbooks often mention general relativity as one of the motivations for it. Spherical Earth theory and evolution are taught in K-12 education too, but the absence of scientific worldviews in those subjects is still pretty high. 

In this case, of course, the issue is mostly just lack of knowledge, rather than actual science denial. You can't deny science knowledge you never knew about in the first place. In the same vein, you can't deny the existence of quantum tunneling, or quantum entanglement, or quarks (concepts that are often first formally introduced in intermediate level undergraduate science courses), unless you've learned about these scientific discoveries in the first place and then rejected their validity.

See also, a new study on the percentage of Gen X members who believe in evolution at different ages. The study is: 

Jon D. Miller, et al., "The acceptance of evolution: A developmental view of Generation X in the United States." Public Understanding of Science (2024). DOI: 10.1177/09636625241234815

Wednesday, April 24, 2024

Avar Sex And Marriage Patterns From Ancient DNA

The Avars (see also here and here) were a historically attested Altaic (probably Turkic) language speaking people of Eastern Europe who expanded as far as Hungary and included much of what is now Ukraine.

The Avar Khaganate and surroundings circa 602 CE.
Image from Wikipedia

The Avars conquered a region that had previously been Slavic for two or three hundred years, although that linguistic character wasn't all that old at the time. Slavic expansion started sometime around the 200s CE in the Kiev culture.

In Hungary, a couple of centuries after the fall of the Avar Khaganate (567 to 822 CE), a small group of Uralic language speaking barbarian Magyar conquerers from the East would arrive, and transfer their language through elite dominance to Hungary which gave rise to the modern Hungarian language, even though they had little demic (i.e. population genetic) impact.

The Avar Khaganate period overlaps heavily with the Migration Period of "barbarian" peoples in Europe.

The latest 2024 study of ancient Avar genetics, following 2020 and 2022 studies linked above, is making headlines at CNN, mostly because it shows that many elite men had children with more than one woman, and that many elite women had children with more than one man, in many cases the multiple partners were siblings. 

This doesn't necessary indicate polygamy, although that is the mostly likely explanation for the men who had children with multiple partners, as there could be successive marriages in an age where early deaths were common. The women who had children with more than one man were probably widows who remarried a man who was a relative of their first husband.

The detail of the ancient DNA results combined with anthropological data and historical attestations from neighboring literate societies is so fine and rich that one could write an epic historical fiction narrative about it that would correspond fairly closely to reality, with the rise and fall of an empire, the replacement of an Avar lord with a new one in one location, and lots of juicy romantic and marital connections. 
Ancient DNA is spilling more secrets about the Avars, a fearsome people who built a mysterious empire that ruled much of Central and Eastern Europe for 250 years from the mid-sixth century.

Primarily known from the accounts of adversaries, the Avars confounded the Byzantines with formidable horseback warriors who appeared suddenly on their doorstep. The enigmatic nomads came en masse from the Mongolian steppe in what was one of the biggest and fastest long-haul migrations in ancient history.

With opulent graves but no written records, the empire and its people have remained largely in the shadows of history until recently. But a landmark April 2022 study involving ancient DNA taken from the graves of the Avar elite shed light on the empire’s far-flung origins.
Now, a new study analyzing the remains of 424 people buried in four cemeteries unearthed in Hungary has revealed details about Avar family and social life and how the newcomers interacted with the population of their adopted homeland. 
. . .
The researchers were able to build detailed family trees or pedigrees, the largest of which spanned nine generations across 2½ centuries. The team discovered that around 300 of the individuals had a close relative buried in the same cemetery.

The analysis showed that men stayed in their community after marriage, while women married outside their original community — a pattern known as patrilocality.

“For all the mothers, we don’t find the parents. The parents aren’t at the site. While all the males are the descendants of the founders,” said Guido Alberto Gnecchi-Ruscone, lead author of the study that appeared Wednesday in the journal Nature.

Study of mitochondrial DNA, which reveals the female line, showed a high variability, suggesting that the women who married into the Avar groups were from different places, according to Gnecchi-Ruscone, a postdoctoral researcher of archaeogenetics at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. They still shared a “steppe” genetic ancestry, indicating that they were probably not conquered local people. 
. . . 

What’s more, the study found, it was relatively common for both men and women in Avar society to have children with multiple partners.

In the case of men, researchers found two partners in 10 cases, three partners in four cases and four partners in one case. Having multiple wives may have been relatively common in the general population as well as the elite, the study authors wrote.

The team also uncovered multiple cases of closely related male individuals having offspring with the same female partner: three pairs of fathers and sons, two pairs of full brothers, and one sibling of paternal half brothers and an uncle and nephew.

Similar “levirate unions” that took place after the death of the woman’s husband existed in other Eurasian steppe societies, according to the study, and suggests that the Avars, who abandoned their nomadic way of life based on herding and became more settled shortly after arriving in Europe, clung to some aspects of their former way of life. 

From CNNThe new study and its abstract are as follows:

From AD 567–568, at the onset of the Avar period, populations from the Eurasian Steppe settled in the Carpathian Basin for approximately 250 years. Extensive sampling for archaeogenomics (424 individuals) and isotopes, combined with archaeological, anthropological and historical contextualization of four Avar-period cemeteries, allowed for a detailed description of the genomic structure of these communities and their kinship and social practices. 
We present a set of large pedigrees, reconstructed using ancient DNA, spanning nine generations and comprising around 300 individuals. We uncover a strict patrilineal kinship system, in which patrilocality and female exogamy were the norm and multiple reproductive partnering and levirate unions were common. 
The absence of consanguinity indicates that this society maintained a detailed memory of ancestry over generations. 
These kinship practices correspond with previous evidence from historical sources and anthropological research on Eurasian Steppe societies. 
Network analyses of identity-by-descent DNA connections suggest that social cohesion between communities was maintained via female exogamy
Finally, despite the absence of major ancestry shifts, the level of resolution of our analyses allowed us to detect genetic discontinuity caused by the replacement of a community at one of the sites. This was paralleled with changes in the archaeological record and was probably a result of local political realignment.
Guido Alberto Gnecchi-Ruscone, et al., "Network of large pedigrees reveals social practices of Avar communities" Nature (April 24, 2024) (open access). https://doi.org/10.1038/s41586-024-07312-4

Tuesday, April 23, 2024

Old News: The Spread Of The Neolithic Revolution In Europe

This map from 2006 has largely withstood the test of time. 

Some key observations that might otherwise be forgotten or overlooked:

* The initial Fertile Crescent Neolithic saw different crops and animals domesticated by genetically distinct modern human populations in different places across the Fertile Crescent. The Neolithic Revolution only expanded once the domesticated plants and animals found at various locations within the Fertile Crescent were consolidated into a single combined package of domesticates. 

* The European Neolithic revolution shared a common origin from Western Anatolia, to the Acreamic Neolithic in Crete, to Thessalia in Greece, to the rest of Greece and the Balkans, before forking off into Mediterranean and terrestrial European branches. The Fertile Crescent Neolithic package added some secondary domesticates in the process of this shared early expansion.

* The Western Mediterranean Neolithic (a.k.a. Cardial Pottery), was several centuries earlier than the early LBK (a.k.a. Linear Pottery) Neolithic in central Europe.

* The LBK Neolithic in central Europe started off in only the best land for farming, mostly along major rivers, and then expanded later into arable, but less optimal farming land.

* There was a mass migration of herders derived from the Mediterranean Neolithic the migrated along a narrow stretch of land, roughly in Eastern France, from Southern France towards central Europe at about the same time as the early LBK.

* As late as 4900 BCE large swaths of Europe had still not experienced the Neolithic Revolution and were still inhabited by European hunter-gatherers whose ancestors had migrated to Europe in the Mesolithic era.

* The Neolithic Revolution in Egypt, West Asia, and the Indus River Valley, were derived from the Fertile Crescent Neolithic Revolution as well, but are not shown on the map below.  These Neolithic expansions also picked up some secondary domesticated plants and animals along the way, like the donkey which was domesticated in Egypt. In Egypt, the Neolithic Revolution increased the population density in the Nile Basin by roughly a hundred-fold.

Source: Detlef Gronenborn, "Ancient DNA from the First European Farmers in 7500-Year-Old Neolithic Sites", 312 Science (June 30, 2006).

Monday, April 22, 2024

Two More Big Ancient DNA Papers

Eurogenes points out two more major European ancient DNA papers at bioRxiv (a pre-print server):

Germanic-speaking populations historically form an integral component of the North and Northwest European cultural configuration. According to linguistic consensus, the common ancestor of the Germanic languages, which include German, English, Frisian, Dutch as well as the Nordic languages, was spoken in Northern Europe during the Pre-Roman Iron Age. 
However, important questions remain concerning the earlier Bronze Age distribution of this Indo-European language branch in Scandinavia as well as the driving factors behind its Late Iron Age diversification and expansion across the European continent. 
A key difficulty in addressing these questions are the existence of striking differences in the interpretation of the archaeological record, leading to various hypotheses of correlations with linguistic dispersals and changes in material culture. Moreover, these interpretations have been difficult to assess using genomics due to limited ancient genomes and the difficulty in differentiating closely related populations. 
Here we integrate multidisciplinary evidence from population genomics, historical sources, archaeology and linguistics to offer a fully revised model for the origins and spread of Germanic languages and for the formation of the genomic ancestry of Germanic-speaking northern European populations, while acknowledging that coordinating archaeology, linguistics and genetics is complex and potentially controversial. We sequenced 710 ancient human genomes from western Eurasia and analysed them together with 3,940 published genomes suitable for imputing diploid genotypes. 
We find evidence of a previously unknown, large-scale Bronze Age migration within Scandinavia, originating in the east and becoming widespread to the west and south, thus providing a new potential driving factor for the expansion of the Germanic speech community. This East Scandinavian genetic cluster is first seen 800 years after the arrival of the Corded Ware Culture, the first Steppe-related population to emerge in Northern Europe, opening a new scenario implying a Late rather than an Middle Neolithic arrival of the Germanic language group in Scandinavia. Moreover, the non-local Hunter-Gatherer ancestry of this East Scandinavian cluster is indicative of a cross-Baltic maritime rather than a southern Scandinavian land-based entry. 
Later in the Iron Age around 1700 BP [250 CE], we find a southward push of admixed Eastern and Southern Scandinavians into areas including Germany and the Netherlands, previously associated with Celtic speakers, mixing with local populations from the Eastern North Sea coast. 
During the Migration Period (1575-1200 BP [375-750 CE]), we find evidence of this structured, admixed Southern Scandinavian population representing the Western Germanic Anglo-Saxon migrations into Britain and Langobards into southern Europe. During the Migration Period, we detect a previously unknown northward migration back into Southern Scandinavia, partly replacing earlier inhabitants and forming the North Germanic-speaking Viking-Age populations of Denmark and southern Sweden, corresponding with historically attested Danes. However, the origin and character of these major changes in Scandinavia before the Viking Age remain contested. 
In contrast to these Western and Northern Germanic-speaking populations, we find the Wielbark population from Poland to be primarily of Eastern Scandinavian ancestry, supporting a Swedish origin for East Germanic groups. In contrast, the later cultural descendants, the Ostrogoths and Visigoths are predominantly of Southern European ancestry implying the adoption of Gothic culture. 
Together, these results highlight the use of archaeology, linguistics and genetics as distinct but complementary lines of evidence.

The north Black Sea (Pontic) Region was the nexus of the farmers of Old Europe and the foragers and pastoralists of the Eurasian steppe, and the source of waves of migrants that expanded deep into Europe. We report genome-wide data from 78 prehistoric North Pontic individuals to understand the genetic makeup of the people involved in these migrations and discover the reasons for their success. 
First, we show that native North Pontic foragers had ancestry not only from Balkan and Eastern hunter-gatherers but also from European farmers and, occasionally, Caucasus hunter-gatherers. 
More dramatic inflows ensued during the Eneolithic, when migrants from the Caucasus-Lower Volga area moved westward, bypassing the local foragers to mix with Trypillian farmers advancing eastward. People of the Usatove archaeological group in the Northwest Pontic were formed ca. 4500 BCE with an equal measure of ancestry from the two expanding groups
A different Caucasus-Lower Volga group, moving westward in a distinct but temporally overlapping wave, avoided the farmers altogether, and blended with the foragers instead to form the people of the Serednii Stih archaeological complex. 
A third wave of expansion occurred when Yamna descendants of the Serednii Stih forming ca. 4000 BCE expanded during the Early Bronze Age (3300 BCE). The temporal gap between Serednii Stih and the Yamna expansion is bridged by a genetically Yamna individual from Mykhailivka in Ukraine (3635-3383 BCE), a site of uninterrupted archaeological continuity across the Eneolithic-Bronze Age transition, and the likely epicenter of Yamna formation. 
Each of these three waves propagated distinctive ancestries while also incorporating outsiders during its advance, a flexible strategy forged in the North Pontic region that may explain its peoples’ outsized success in spreading their genes and culture across Eurasia.
Davidski at Eurogenes comments that:
All of these studies are very useful, but there are some problems with each of them. Indeed, I'd say that the authors of the Lazaridis and McColl preprints need to reevaluate the way that they use ancient DNA to solve their linguistic puzzles. Once they do that their conclusions are likely to change significantly.

I tend to agree and will flesh out this post later as time becomes available. 

As an aside, stylistically, I think that it is poor form to put footnotes and references in a journal article abstract. I omit them per my standard formatting standards linked in the sidebar, when I quote them at this blog.

Thursday, April 18, 2024

The Genetic Origins Of The Indo-Europeans

A major new preprint of a paper on Indo-European genetic origins is out. The genetic information is interesting. The linguistic and historical analysis still isn't great, but this paper, at least, seems to abandon previous flawed Anatolian origin and Neolithic origin theories for the Indo-European languages. 

Hat tip to @Ryan for the link to the new paper.

The Yamnaya archaeological complex appeared around 3300 BCE across the steppes north of the Black and Caspian Seas, and by 3000 BCE reached its maximal extent from Hungary in the west to Kazakhstan in the east. To localize the ancestral and geographical origins of the Yamnaya among the diverse Eneolithic people that preceded them, we studied ancient DNA data from 428 individuals of which 299 are reported for the first time, demonstrating three previously unknown Eneolithic genetic clines. 
First, a "Caucasus-Lower Volga" (CLV) Cline suffused with Caucasus hunter-gatherer (CHG) ancestry extended between a Caucasus Neolithic southern end in Neolithic Armenia, and a steppe northern end in Berezhnovka in the Lower Volga. Bidirectional gene flow across the CLV cline created admixed intermediate populations in both the north Caucasus, such as the Maikop people, and on the steppe, such as those at the site of Remontnoye north of the Manych depression. CLV people also helped form two major riverine clines by admixing with distinct groups of European hunter-gatherers. 
A "Volga Cline" was formed as Lower Volga people mixed with upriver populations that had more Eastern hunter-gatherer (EHG) ancestry, creating genetically hyper-variable populations as at Khvalynsk in the Middle Volga. 
A "Dnipro Cline" was formed as CLV people bearing both Caucasus Neolithic and Lower Volga ancestry moved west and acquired Ukraine Neolithic hunter-gatherer (UNHG) ancestry to establish the population of the Serednii Stih culture from which the direct ancestors of the Yamnaya themselves were formed around 4000 BCE. This population grew rapidly after 3750-3350 BCE, precipitating the expansion of people of the Yamnaya culture who totally displaced previous groups on the Volga and further east, while admixing with more sedentary groups in the west. 
CLV cline people with Lower Volga ancestry contributed four fifths of the ancestry of the Yamnaya, but also, entering Anatolia from the east, contributed at least a tenth of the ancestry of Bronze Age Central Anatolians, where the Hittite language, related to the Indo-European languages spread by the Yamnaya, was spoken. 
We thus propose that the final unity of the speakers of the "Proto-Indo-Anatolian" ancestral language of both Anatolian and Indo-European languages can be traced to CLV cline people sometime between 4400-4000 BCE.
Iosif Lazaridis, et al., "The Genetic Origins of the Indo-Europeans" bioRxiv (April 17, 2024).

The paper's conclusion lays out a narrative, which has some merit, although I'm skeptical of some of their analysis, including the Anatolian part. 
The origin and spread of the first speakers of Indo-Anatolian languages 
Different terminologies exist to designate the linguistic relationship of Anatolian and IndoEuropean languages. The traditional view includes both within an “Indo-European” (IE) group in which Anatolian languages usually represent the first split. An alternative terminology, which we use here, names the entire linguistic group “Indo-Anatolian” (IA) and uses IE to refer to the set of related non-Anatolian languages such as Tocharian, Greek, Celtic, and Sanskrit. Dates between 4300-3500 BCE have been proposed for the time of IA split predating both the first attestation of the Hittite language in Central Anatolia (post-2000 BCE) and the expansion of the Yamnaya archaeological culture (post-3300 BCE). 
We identify the Yamnaya population as Proto-IE for several reasons. First, the Yamnaya were formed by admixture ~4000 BCE and began their expansion during the middle of the 4th millennium BCE, corresponding to this linguistic split date between IE and Anatolian. Second, the Yamnaya were the source of the Afanasievo migration to the east a leading candidate for the split of the ancestral form of Tocharian, widely recognized as the second split after that of Anatolian. Third, the Yamnaya can be linked to the languages of Armenia via both autosomal and Y-chromosome ancestry after ~2500 BCE, and to the languages of the Balkans such as Greek. Fourth, the Yamnaya can be linked indirectly to other IE speakers via the demographically and culturally transformative Corded Ware and Beaker archaeological cultures of the 3rd millennium BCE that postdate it by centuries. Most people of the Corded Ware culture of central-northern Europe had about three quarters of Yamnaya ancestry, a close connection within a few generations that can be traced to the late 4th millennium BCE. The Beaker archaeological culture of central-western Europe also shared a substantial amount of autosomal ancestry with the Yamnaya and were also linked to them by their possession of R-M269 Y-chromosomes. The impact of these derivative cultures in Europe leaves no doubt that they were linguistically Indo-European as most later Europeans were; the Corded Ware culture itself can also be tentatively linked via both autosomal ancestry and R-M417 Y-chromosomes with Indo-Iranian speakers via a long migratory route that included Fatyanovo and Sintashta intermediaries. 
A recent study proposed a much deeper origin of IA/IE languages to ~6000  BCE or about two millennia older than our reconstruction and the consensus of other linguistic studies. The technical reasons for these older dates will doubtlessly be debated by linguists. From the point of view of archaeogenetics, we point out that the post-3000 BCE genetic transformation of Europe by Corded Ware and Beaker cultures on the heels of the Yamnaya expansion is hard to reconcile with linguistic split times of European languages consistently >4000 BCE as no major pan-European archaeological or migratory phenomena that are tied to the postulated South Caucasus IA homeland ~6000 BCE can be discerned.  
The Yamnaya culture stands as the unifying factor of all attested Indo-European languages. Yet, the homogeneity of the Yamnaya patrilineal community was formed out of the admixture of diverse ancestors, via proximal ancestors from the Dnipro and CLV clines. Yamnaya and Anatolians share ancestry from the CLV Cline, and thus, if the earliest IA language speakers shared any genetic ancestry at all—the possibility of an early transfer of language without admixture must not be discounted—then the CLV Cline is where this ancestry must have come from. On the Anatolian side, we see that ancestry from the southern Caucasus Neolithic end of the CLV Cline was impactful during the Chalcolithic and Bronze Ages and Bronze Age Central Anatolians over the time span of Hittite presence there also had traces of Lower Volga-related ancestry which implies an origin north of the Caucasus. On the steppe side, we see that mixed Lower Volga/Caucasus Neolithic ancestry was present in the Dnipro Cline and maximized in the Yamnaya population along that cline. IBD analysis identifies long (≥30cM) segments shared by Eneolithic individuals from Berezhnovka-2 in the Lower Volga with Khvalynsk, Igren-8 Serednii Stih, and Areni-1 Armenian Chalcolithic populations, providing strong direct evidence for the impact of Lower Volga ancestry on the Middle Volga, Dnipro, and South Caucasus regions, and active gene flow among these regions around the time the sampled individuals lived. The individual from Vonyucka-1 in the North Caucasus, in fact, has an IBD link (15.2cM) with an early Bronze Age Anatolian from Ovaören. Indo-Anatolian languages must have been spread widely by people carrying CLV cline ancestry >4000 BCE. However, only two descendant groups transmitted their languages to later groups: the Yamnaya in the Dnipro-Don area, aided by the mobility of their horse-wagon technology, and the Proto-Anatolians in the south, surviving in the diverse linguistic landscape of ancient Western Asia long enough for their languages to be recorded in writing after 2000 BCE. Whatever their deeper origins in time out of the diverse constituents of CLV cline populations, the Indo-Anatolians must have been part of that cline. Genetics has little to say whether within this cline the IA languages were first spoken in the Caucasus end of the cline and spread into the steppe along with the spread of Caucasus ancestry, or vice versa, or even if a linguistic unity uncoupled with ancestry existed within the CLV continuum. DNA has traced back the ancestors of both Anatolian and IE speakers to the part of the CLV Cline that was north of the Caucasus mountains, bringing them into proximity with each other and uncovering their common CLV ancestry. However, it cannot adjudicate, on its own, who among the proximate and diverse distal ancestors of the CLV people were Pre-IA speaking. Future studies of the dynamics and temporality of intra-CLV contacts (to which genetics may add its information) and of the cultures of CLV people (as reconstructed by archaeology and linguistics) may decide who among them were most likely to have been the “original” Indo-Anatolians. 

Linguistic evidence has been advanced in favor of different solutions of the Proto-IE origins problem for more than two centuries and we review some recent proposals relevant to our reconstruction of early IA/IE history.

First, the presence of some cereal terminology in IA languages and even more in IE was suggested to reflect a subsistence strategy that relied in part on agriculture; this was interpreted as providing evidence against a geographic origin of the populations that spread Indo-European languages east of the Dnipro valley, the easternmost point in which agriculture was used (along with foraging and herding) during the Eneolithic. Our genetic findings are consistent with this constraint. If a Caucasus Neolithic population like that at Aknashen spread IA languages to the north (via the CLV cline to the Dnipro-Don area) it would almost certainly have had a cereal vocabulary, and then this vocabulary would have been retained during the Serednii Stih culture of the Eneolithic down to the time of the Yamnaya as agriculture continued to be used there. 

Second, the fact that Anatolian languages are attested largely in western Anatolia has been interpreted as evidence for entry into Anatolia from the west (via the Balkans), and thus we need compelling genetic evidence to provide a strong synthetic case for an eastern route. In fact, however, our genetic data does provide such a strong case, greatly increasing the plausibility of scenarios of an eastern entry of Proto-Anatolian speaking ancestors into Anatolia. This is because we find that Central Anatolian Early Bronze Age people who were plausibly speakers of Anatolian languages based on their archaeological contexts, were striking genetic outliers from their neighbors due to having a minority component of their ancestry from the CLV (plausibly from the people who brought the ancestral form of Anatolian languages to Anatolia), the majority of their ancestry from Mesopotamian Neolithic farmers, and little or no ancestry from the Neolithic and Chalcolithic Anatolians who were overwhelming the source populations of other Early Bronze Age Anatolians. Mesopotamian Neolithic ancestry almost certainly had an eastern geographic distribution, while the Central Anatolian Bronze Age people had no evidence of the European farmer or European hunter-gatherer ancestry that CLV have encountered if they had migrated to Anatolia from the west, so the genetic data favor an eastern route. 
How then could it be that there is no linguistic evidence of Anatolian speakers in eastern Anatolia? 

We propose that the archaeologically momentous expansion of the Kura-Araxes archaeological culture in the Caucasus and eastern Anatolia after around 3000 BCE may have driven a wedge between steppe and West Asian speakers of IA languages, isolating them from each other and perhaps explaining their survival in western Anatolia into recorded history. That the expansion of the Kura-Araxes archaeological culture could have had a profound enough demographic impact to have pushed out Anatolian-speakers, is attested by genetic evidence showing that in Armenia, the spread of the Kura-Araxes culture was accompanied by the complete disappearance of CLV ancestry that had appeared there in the Chalcolithic. 
The Kura-Araxes culture may not be the only reason for the IA split. The ancestors of the Yamnaya did not only become separated from their Anatolian linguistic relatives but from other steppe populations as well. The homogenization of the Yamnaya ancestral population during the 4th millennium BCE, both in terms of its autosomal ancestry, and in terms of its Y-chromosome lineage, attest to a period of relative isolation and the cessation of admixture. Such isolation would foster linguistic divergence of the languages spoken in the pre-Yamnaya community with those of their linguistic relatives on the steppe. This isolation must have persisted even after the sudden appearance of the Yamnaya archaeological horizon. Mobility and geographical dispersal provided ample opportunities for the resumption of admixture, yet the genetic homogeneity of the “Core Yamnaya” across much of the steppe leaves little room for the absorption of any pre-existing steppe communities: they all seem to disappear in the face of the Yamnaya juggernaut. Did mixing occur between the segment of the Yamnaya population not buried in kurgans and locals they encountered while the kurgan-buried elite largely avoided it with some exceptions? 

The rise of the Yamnaya in the Steppe at the expense of their predecessors was followed by their demise after a thousand years, displaced by descendants of people of the Corded Ware culture. Was this the demise of the kurgan elites of the Yamnaya or of the population as a whole? 

The steppe was dominated by many and diverse groups later still, such as the Scythians and Sarmatian nomads of the Iron Age. These groups are certainly very diverse genetically, but their kurgans scattered across the steppe attest to the persistence of at least some elements of culture that began in the Caucasus-Volga area seven thousand years ago before blooming, in the Dnipro-Don area, into the Yamnaya culture that first united the steppe and impacted most of Eurasia. To what symbolic purpose did the Yamnaya and their precursors erect these mounds we may not ever fully know. If they aimed to preserve the memory of those buried under them, they did achieve their goal, as the kurgans, dotting the landscape of the Eurasian steppe, drew generations of archaeologists and anthropologists to their study, and enabled the genetic reconstruction of their makers’ origins presented here.

Wednesday, April 17, 2024

Ritual Human Sacrifices In Neolithic Europe

There are about twenty known instances across Neolithic Europe of women being ritually sacrificed in an astrologically aligned grave together with grindstones which were often destroyed after a harvest. Due to the difficulty of finding and properly classifying these sites, the authors acknowledge that 20 cases is an underestimate even among European remains recovered by archaeologists. This was done by dropping them in a pit which was either a repurposed grain storage pit or was designed to mimic one, alive with their throats tied to their ankles so that they eventually strangle themselves, a painful means of death still employed by the Italian mafia in modern times. While involuntary, it this is often seen as a form of symbolic suicide.

The earliest known instance of this practice, in Italy, predates agriculture, but all of the other instances of this practice in Europe arise in the context of the culture of the first farmers of Europe, prior to the metal ages or the migration of Indo-Europeans into the regions where it occurred. This practice may have been adopted by the first farmers of Europe from the European hunter-gathers whom they took perhaps a thousand years of co-existence in any one place to largely replace.

"Retainer sacrifice", often involving slaves or concubines, is well-attested from prehistoric times into the end of the pre-Christian era in Indo-European peoples. But the precise Neolithic human sacrifice associated with the harvest described in the new paper below does not appear to have carried over into the Indo-European metal age period in Europe. Indo-European religious practices superseded those of the first farmers of Europe.

The hunter-gather example, depicted in ancient artwork (shown in a figure below) that was not accompanied by remains, involved two sacrificed men and an excited group including several people wearing bird masks. The later sites include:
20 individuals (nine men, seven women, and four children) from 16 tombs or pits at 14 archaeological sites. The oldest sites (5400 to 4800 BCE) are from the Brno-Bohunice from Linear Pottery culture or linearbandkeramik (LBK) culture in the Czech Republic. The most recent (4000 to 3500 BCE) are the three individuals found at Saint-Paul-Trois-Châteaux in the Rhône Valley and one in Catalonia.

The numbers in brackets refer to the site numbers on the map. Blue dagger, male; red dagger, female; black dagger, undetermined; dagger in box, immature. PAL, Italian Paleolithic culture; LBK, Linearbandkeramik or linear pottery culture; VBQ I, square-mouthed vase culture (first phase); Münchs., Münchshofen culture; BG, Bischeim-Gatersleben transition; SF, Sepulcros de Fosa; Ch, Chassey culture. . . . B.P., before the present.
There were at least three distinct religious and burial cultures at the time in Europe, and this practice was restricted to first farmers of Europe with a pit tomb burial tradition. This practice was not shared by contemporaneous megalithic first farmers, like those associated with Stonehenge, or with contemporaneous first farmer cultures that buried people under large slabs in the Alps.

19th century European folklore describes similar practices attributed to the deep past, generally involving young women.

In an example initially discovered in 1985, that is the touchstone of a new paper just fully analyzing the find now, where three women's bodies were found, two younger women were ritually sacrificed (one with pieces of a broken grindstone on her back), and one woman who died in her fifties and was placed in the pit at the same time was interred in a covering in a non-sacrificial manner with a vase serving as a form of grave goods who would have been the only body visible from above. In the case of the two women who were sacrificed:

(D) Detailed view of the individual (woman 3) in a prone position with a box-shaped stone on the left half of her remains (white square). The upside-down grindstone fragment next to the box-shaped stone covers the head of the individual lying underneath (white circle). The scale displays 50 cm
fragments of grindstone were forcefully inserted during the positioning of the women, thus blocking the two bodies. . . . they could no longer move, and breathing became very difficult. . . . In such a position, death occurs relatively quickly, even if the victims were not drugged or beaten. The prone position induces inadequate ventilation and a decrease in the blood volume pumped by the heart, which can lead to pulseless electrical activity arrest and/or cardiac arrest by asystole. This diagnosis, formerly known as positional asphyxia, could now be better defined as “prone restraint cardiac arrest.” . . . cervical compression is an aggravating factor, as is obstruction of the nose and mouth. The . . . position of the lower limbs of woman 3 . . . suggests a potential case of homicidal ligature strangulation. . . . the woman would have been on her abdomen with a ligature attached to her ankles and neck. The fact that the woman was obstructed by grindstones and the overhang of the storage pit, coupled with . . . a tie connecting her ankles to her neck, supports the hypothesis of a deposit while she was still alive. 
The sacrificial pits would have been under an oval shaped structure made of perishable materials at the time of the sacrifice.

The paper and its abstract are as follows:
In the Rhône Valley’s Middle Neolithic gathering site of Saint-Paul-Trois-Châteaux (France), the positioning of two females within a structure aligned with the solstices is atypical. Their placement (back and prone) under the overhang of a silo in front of a third in a central position suggests a ritualized form of homicidal ligature strangulation. The first occurrence dates back to the Mesolithic, and it is from the Early Neolithic of Central Europe that the practice expands, becoming a sacrificial rite associated with an agricultural context in the Middle Neolithic. Examining 20 cases from 14 sites spanning nearly two millennia from Eastern Europe to Catalonia reveals the evolution of this ritual murder practice.

The introduction to the paper provides useful context:
The topic of human sacrifice, its significance in understanding human societies, and its archaeological study are subjects of active debate and interest. The debate around this issue has sparked lively discussions across various fields, including the humanities, as well as social and ecological sciences. In the context of the Neolithic period in Europe, scholars have been particularly intrigued by the concept of human sacrifice. The prevailing archaeological interpretation of human sacrifice during this era, influenced by the social control hypothesis, often sees it as a form of retainer sacrifice, where officiants killed enslaved people, servants, relatives, wives, concubines, or others to accompany their masters, social superiors, or relatives into the afterlife. An alternative viewpoint suggests that human sacrifice might have played a role in ideological integration within agrarian societies rather than being solely a feature of hierarchical societies. Moreover, there has long been suspicion of agricultural rituals predominantly involving female participants during the European Neolithic. One of the earliest signs of agrarian rites could be in the ritual destruction of grindstones––a symbol of agriculture and harvest—which is a tradition that may have been especially widespread in the Mediterranean region; in other sites, the remains of fauna are notable, with notable sacrifices of dogs and bovids. We should note that human sacrifice to obtain abundant harvests is not an exceptional occurrence in farming societies and is particularly well documented for specific historical periods. In some well-documented cases, the breakdown by sex and age of the individuals sacrificed shows that, depending on the case, they could have been children, young women, or even adults. In Europe, particularly in Central Europe, there were still abundant traces of such sacrifices (especially of young women) in folklore in the 19th century, and this was the source of one of the most famous writings by J. G. Frazer, one of the fathers of religious anthropology. 
The principal challenge in archeology, especially in prehistory where written records are absent, is distinguishing ritual sacrifice from other forms of ritualized violence. To investigate formal sacrifice, defined as the killing of humans for ritual purposes, researchers seek recurrent patterns of behavior that deviate from the norm and that archeologists can hypothesize as sacrificial. The examination of “deviant burials”, i.e., those that differ from conventional burial practices for a specific population, along with methods of execution becomes essential. Several criteria for exploring the hypothesis of human sacrifices have been established, including indicators of violent death, unusual body positions or burial patterns, multiple concurrent burials, hierarchically related body placements, the inclusion of individuals with or instead of offerings, the distinctive arrangement of individuals, and demographic irregularities. The challenge lies in determining the threshold for classifying a burial as atypical, similar to identifying instances of violent death when no obvious signs of lethal trauma are present on skeletal remains. The postulation of human sacrifice emerges when human remains exhibit indicators of a violent demise and appear within contexts deviating from established patterns typical of interred bodies. These contexts encompass scenarios in which an individual subjected to violence is not laid to rest within the confines of a conventional burial site, and their treatment differs from the customary rites accorded to the deceased. Archaeological records most robustly support sacrificial practices when a substantial dataset exhibits a recurring constellation of distinct characteristics. Moreover, when we observe a recurring pattern of several diagnostic traits over centuries, and when there is an absence of individuals accompanied by prestige objects, the hypotheses developed favor ritual sacrifices more than retainer sacrifices
Within the Rhône Valley at the end of the Middle Neolithic period—in this region, the Middle Neolithic is between 4250 and 3600/3500 Before Common Era (BCE)—expansive sites spanning several hectares are arranged in a distinct pattern of land use and management. These sites exhibit a wealth of features, including numerous silos, numerous broken grindstones, ceramics sourced from distances spanning several tens of kilometers, animal remains indicative of communal meals, instances of animal sacrifices, and graves containing individuals found in configurations reminiscent of silos or resembling such structures. While the notion of abandoned villages has been proposed for similar sites in proximity to the Mediterranean, the discovery at Saint-Paul-Trois-Châteaux, where two women were found in an unconventional placement beneath the overhang of a storage pit, positioned in front of a third body (a woman) in a central location, suggests a ritualized form of asphyxiation that may even imply a method of homicidal ligature strangulation. Given that the silo containing these bodies is part of an architectural orientation toward solstices, we lean toward the hypothesis that these sites, at a certain juncture in their history, functioned as collective gathering places where food security and the agricultural cycle were venerated, particularly through the practice of human sacrifices
Homicidal ligature strangulation involves a ritualized form of ligature strangulation, characterized by its cruelty, in which, in its classical way, the victim, in a prone position, is bound at the throat and ankles with a rope. Self-strangulation becomes inevitable due to the forced position of the legs. Currently, this torture, known as incaprettamento, is associated with the Italian Mafia and is sometimes used to punish persons perceived as traitors. In various circumstances, killing people with homicidal ligature strangulation has been interpreted as a form of symbolic suicide, as it is the individual who, by strangling themselves, causes their death. The earliest recorded instance of homicidal ligature strangulation dates back to the Italian Mesolithic era, possibly suggesting a highly ancient origin within ceremonial sites (Fig. 1).
Fig. 1. Mesolithic rock art scene from the Addaura Cave.

According to J. Guilaine, this scene features eleven humans and a deer, which, given its position, is most likely deceased (sacrificed?). Nine of the humans are standing (in gray); several of them are adorned with bird-like beak faces, resembling masks, and they all appear highly animated. The artist aimed to convey a sense of general excitement. They encircle two central humans (highlighted by us in black), in a prone position. They lie on their abdomens with their legs folded beneath them; one has their arms hanging, while the other has them folded behind their neck. There is a rope stretched between their ankles and neck. Male genitalia in the two figures are very clearly depicted, as if erect, and the figure underneath is shown with their tongue hanging out; these two signs are found in cases of strangulation or hanging.
Considering the observation of the Rhône Valley and the Mesolithic case, we have investigated, as a basis for research and insights into the socio-religious structuring of a segment of the European Neolithic, similar cases on the Ancient (5500 to 4900 BCE) and Middle Neolithic periods (4250 to 3600/3550 BCE) in Central and Western Europe. This study examines 20 cases spanning nearly 2000 years from Eastern Europe to Catalonia. These cases originated from archaeological sites on alluvial plains, either on major rivers (Danube, Oder, Rhine, Pô) or on coastal rivers on the Mediterranean coast with a distribution quite different from that of the megalithic sites of the same period. In these regions, funeral sites are mostly represented by repurposed storage pits or pits dug like silos or ritual silos, where archeologists found one or more individuals or isolated bones. The deposit of human remains in circular pits was widespread throughout the Carpathian Basin, the Rhine Valley, the Rhône Valley, southern France, southwestern France, Emilia, Italy, and the coast of Catalonia. In these sites, while some skeletons are in a flexed position—a standard position for this period—others are placed in atypical positions or buried unconventionally, which does not conform to the overall pattern. If, in some cases, deaths by stabbing or arrowheads have sometimes been described and if sometimes, researchers interpret these atypical positions as if the individuals had been unceremoniously thrown into the pits, in most cases, the cause of death is unknown, even if one hypothesizes that these individuals in atypical positions are cases of retainer sacrifice. These documented cases underscore the possible development of sacrificial practices in various regions and contexts. Particularly noteworthy are instances of homicidal ligature strangulation found in ritual sites during the Neolithic period. These sites often included storage pits used for burials, occasionally accompanied by sacrificial offerings, broken grindstones, and isolated human remains. This investigation contributes valuable insights into the intricate nature of human sacrifice and ritualized violence during the European Neolithic, questioning established interpretations and highlighting the importance of thorough archaeological analysis for a nuanced understanding of these practices.

Tuesday, April 16, 2024

Making More Nails

4gravitons has an excellent post entitled Making More Nails. It begins as follows:

They say when all you have is a hammer, everything looks like a nail.

Academics are a bit smarter than that. Confidently predict a world of nails, and you fall to the first paper that shows evidence of a screw. There are limits to how long you can delude yourself when your job is supposed to be all about finding the truth.

You can make your own nails, though.

Sunday, April 14, 2024

String Theory Didn't Work Out

String theory makes no predictions and has no observational support. It isn't really even really a theory so much as an approach to come up with a theory that no one has managed to set forth yet.

Friday, April 12, 2024

Peter Higgs Has Died

Peter Higgs, the theoretical physicist whose name graces the Higgs boson, died this week.

Wednesday, April 10, 2024

Y-DNA E22 In China

The Y-DNA E-V22 clade has an interesting distribution that even includes a dozen sampled individual in China. One of the nice things about uniparental historical genetics is that it naturally invites efforts to construct an eminently understandable narrative that explains it.

Also bonus points for the use of the term "brother lineage" to describe Y-DNA clades.
[T]he phylogeny of E-V22, at least based on the samples uploaded to yFull, reveals the following:
* The E-V22 haplogroup appears to be roughly 11,800 years old, with a “TMRCA,” or time to most-recent common ancestor, of 8,200 “ybp,” or years-before-present.
* While there are many deep and relatively old sublineages whose members have diverse geographical origins, there does appear to be a general pattern of E-V22 prevalence in/among the following regions and populations: the Arabian Peninsula and the Arab states of the Persian Gulf; diverse Jewish and related populations (including Bukharian, Ashkenazi, an apparent Moroccan Jewish, Italki, and Ashkenazi branch, the Samaritans [note: this lineage is apparently that of the Samaritan priestly class], and others); the Saho people, a Cushitic-speaking ethnic group of Eritrea and Ethiopia; and other groups such as Egyptians, Levantine Arabs, Sicilians, and at least one Caucasian-Iranian lineage. (There are Northwestern European exemplars, too.)
* Perhaps surprisingly, there are no fewer than twelve reported samples on yFull with origins in the present-day People’s Republic of China, including a well-developed lineage of Chinese men who report their origins as Dungan, Manchu, Mongol, and in Liaoning [i.e., the gateway to Manchuria], and who share a common paternal-line ancestor who lived about 600 years ago, right around the tail-end of the Mongol Yuan Dynasty. (Note their Czech "brother lineage," with a TMRCA of 5,700 years-before present.) Zooming out a bit farther back on the overall E-V22 phylogeny, three more Chinese samples emerge who are nested within different lineages altogether: a self-described “Mandarin Chinese” isolate lineage with Shandong origins that has a TMRCA of 4,100 years-before-present; a Chinese sample with Mongolian origins who shares a common Armenian paternal-line ancestor as of 4,500 years ago, and who has even more remote Irish and British (exotic for E-V22!) paternal-line cousins; and a rather old Henan-based lineage with a Saudi cousin as of 6,200 years ago, and diverse brother lineages with Nablusi, Moroccan Jewish, and Khorasani Turkish origins, among others (including an apparent ancient Longobard sample unearthed in Hungary).
It is possible to speculate endlessly about the historical migrations that led to E-V22’s present-day distribution, both in China and elsewhere. Yet I note that the Dungan-Manchu-Mongol-Liaoning branch shares as a brother lineage the Caucasian-Iranian group consisting of three samples with respective Talysh, Persian, and Georgian-Azerbaijani origins. Does this nearly 8,000-year-old Irano-Chinese lineage (with a Czech exemplar nested within them) reflect a more recent Silk Road-era migration eastward, or does the Chinese branch have altogether different, more ancient origins? More fodder for speculation: there is an ancient Xiongnu E-V22 sample among the data underlying a study from just last year entitled “Genetic population structure of the Xiongnu Empire at imperial and local scales.” Perhaps the sequencing of more ancient DNA will one day give us the complete historical migratory picture, but the phylogeny of this lineage does seem to point in a westerly direction.

From Language Log

Monday, April 8, 2024

Dark Matter Particles Can't Be Collisionless

A NFW halo density profile would be almost universal if dark matter phenomena were attributable to collisionless dark matter particles. But reality doesn't look like what a collisionless dark matter particle model's predictions at all. 
Conventional studies of galaxy clustering within the framework of halo models typically assume that the density profile of all dark matter haloes can be approximated by the Navarro-Frenk-White (NFW) spherically symmetric profile. However, both modern N-body simulations and observational data suggest that most haloes are either oblate or prolate, and almost never spherical.
From a new preprint which proposes a model of dark matter halos that parameterizes this asymmetry.

The observational data, generically, rules out any collisionless dark matter particle explanations for dark matter phenomena if the particles are not very light and wave-like in their behavior. At a minimum, it rules out all collisionless dark matter particle candidates with masses of more than about 10 keV (possibly much lighter, such as fuzzy dark matter models with particles with a mass of 1−2 × 10−23 eV and other ultralight dark matter models).

The asymmetrical dark matter halo preprint doesn't propose a mechanism by which its asymmetry parameter arises; it is a purely phenomenological formula. 

A self-interacting dark matter particle model could help explain this parameter, but still wouldn't explain the tight correlation between the distribution of ordinary matter in a galaxy and the dark matter phenomena in it that is observed, which would require a different kind of fifth force. 

Any theory attempting to describe dark matter phenomena in which a fifth force mediates interactions between dark matter particles and other dark matter particles, and/or between dark matter particles and ordinary matter, of course, has lost ground with Occam's Razor, relative to a theory that only modifies the equations of gravity, as conventionally applied, without resort to any dark matter particles.

On the other hand, Deur's gravity based model (even if it doesn't actually fully replicate weak field general relativity) can naturally address both concerns, without dark matter particles or dark energy. 

In his model, the asymmetrical distribution of ordinary matter is what gives rise to dark matter in the first place, so inferred dark matter distributions should almost never be spherically symmetric, consistent with what we observe. And, in a gravitationally based model, all dark matter phenomena arise from the ordinary matter distribution, so the tight correlation between ordinary matter distributions and the dark matter phenomena in the galaxy is expected rather than a problem.

Deur's model, of course, is not the only one on offer, although it is one of the best that I've seen so far. Some generalizations of MOND that address, among other things, its shortcomings in galaxy clusters, are discussed in another new preprint.