Wednesday, January 22, 2025

Matriarchal Celts

A new study published in Nature, examining ancient DNA evidence from Iron Age Celtic cemeteries in Southern England, demonstrate that these Celts, at least, were matrilocal

It also demonstrates the demic diffusion of Celts from continental Europe to Southern England, displacing Bronze Age Bell Beaker derived populations that were predominant in the rest of England in the first millennium before the common era. 

The paper's abstract says:

Roman writers found the relative empowerment of Celtic women remarkable. In southern Britain, the Late Iron Age Durotriges tribe often buried women with substantial grave goods. 
Here we analyse 57 ancient genomes from Durotrigian burial sites and find an extended kin group centred around a single maternal lineage, with unrelated (presumably inward migrating) burials being predominantly male. Such a matrilocal pattern is undescribed in European prehistory, but when we compare mitochondrial haplotype variation among European archaeological sites spanning six millennia, British Iron Age cemeteries stand out as having marked reductions in diversity driven by the presence of dominant matrilines. 
Patterns of haplotype sharing reveal that British Iron Age populations form fine-grained geographical clusters with southern links extending across the channel to the continent. Indeed, whereas most of Britain shows majority genomic continuity from the Early Bronze Age to the Iron Age, this is markedly reduced in a southern coastal core region with persistent cross-channel cultural exchange. This southern core has evidence of population influx in the Middle Bronze Age but also during the Iron Age. This is asynchronous with the rest of the island and points towards a staged, geographically granular absorption of continental influence, possibly including the acquisition of Celtic languages.

Tuesday, January 21, 2025

Ethnic Segregation In 8th Century Austria

The Avars from Asia Steppes and European farmers co-existed in segregated communities in the early Middle Ages in Austria for at least six generations.
Researchers carried out an archeogenetic study of human remains from more than 700 individuals from the Early Middle Ages. Two large burial sites, Modling and Leobersdorf, have been genetically analyzed in their entirety. The surprising result was that the individuals from Leobersdorf were mostly of East Asian origin, while those buried in Modling mostly had European ancestry. Both communities lived next to each other for at least six generations. . . . 
[The result] emerged from a genetic study of burial grounds from the Avar period in the 8th century CE. The Avars had arrived in the 6th century from the East Asian Steppes and settled in East Central Europe among a mixed population.
From Science Direct. The article quoted above is based upon the academic paper whose abstract and citation are provided below:
After a long-distance migration, Avars with Eastern Asian ancestry arrived in Eastern Central Europe in 567 to 568 CE and encountered groups with very different European ancestry. 
We used ancient genome-wide data of 722 individuals and fine-grained interdisciplinary analysis of large seventh- to eighth-century ce neighbouring cemeteries south of Vienna (Austria) to address the centuries-long impact of this encounter. We found that even 200 years after immigration, the ancestry at one site (Leobersdorf) remained dominantly East Asian-like, whereas the other site (Mödling) shows local, European-like ancestry. These two nearby sites show little biological relatedness, despite sharing a distinctive late-Avar culture. 
We reconstructed six-generation pedigrees at both sites including up to 450 closely related individuals, allowing per-generation demographic profiling of the communities. Despite different ancestry, these pedigrees together with large networks of distant relatedness show absence of consanguinity, patrilineal pattern with female exogamy, multiple reproductive partnerships (for example, levirate) and direct correlation of biological connectivity with archaeological markers of social status. The generation-long genetic barrier was maintained by systematically choosing partners with similar ancestry from other sites in the Avar realm. Leobersdorf had more biological connections with the Avar heartlands than with Mödling, which is instead linked to another site from the Vienna Basin with European-like ancestry. Mobility between sites was mostly due to female exogamy pointing to different marriage networks as the main driver of the maintenance of the genetic barrier.
Ke Wang, et al., "Ancient DNA reveals reproductive barrier despite shared Avar-period culture." Nature (January 15, 2025) DOI: 10.1038/s41586-024-08418-5 (open access).

Monday, January 20, 2025

Garbage Experiment Of The Day

This experiment is searching for dark matter that must have properties in a part of the dark matter parameter space that direct dark matter detection experiments and particle collider tests have already ruled out by a dozen orders of magnitude or more. It is also basically ruled out by the LAT collaboration.

It is arguably one of the biggest wastes of time in the astronomy community right now. I would never have voted to fund it, if I were sitting on a committee considering the proposal.

Numerous observations confirm the existence of dark matter (DM) at astrophysical and cosmological scales. Theory and simulations of galaxy formation predict that DM should cluster on small scales in bound structures called sub-halos or DM clumps. While the most massive DM sub-halos host baryonic matter, less massive, unpopulated sub-halos could be abundant in the Milky Way (MW), as well and yield high-energy gamma rays as final products of DM annihilation. Recently, it has been highlighted that the brightest halos should also have a sizeable extension in the sky. In this study, we examine the prospects offered by the Cherenkov Telescope Array Observatory (CTAO), a next-generation gamma-ray instrument, for detecting and characterizing such objects. Previous studies have primarily focused on high-latitude observations; here, we assess the potential impact of the CTAO's Galactic Plane Survey, which will provide unprecedentedly deep survey data for the inner five degrees of the Galactic plane. Our modeling accounts for tidal effects on the sub-halo population, examining the conditions under which DM sub-halos can be detected and distinguished from conventional astrophysical sources. We find that regions a few degrees above or below the Galactic plane offer the highest likelihood for DM sub-halo detection. For an individual sub-halo -- the brightest from among various realizations of the MW subhalo population -- we find that detection at the 5σ level is achievable for an annihilation cross section of ⟨σv⟩∼3×10^−25 cm^3/s for TeV-scale DM annihilating into bb¯. For a full population study, depending on the distribution and luminosity model of Galactic sub-halos, yet unconstrained cross sections in the range ⟨σv⟩∼10^−23−10^−22 cm^3/s for TeV DM candidates are necessary for the brightest sub-halos to be detected.
Christopher Eckner, et al., "Detecting dark matter sub-halos in the Galactic plane with the Cherenkov Telescope Array Observatory" arXiv:2501.09789 (January 16, 2025).

Sunday, January 19, 2025

Australopithecus Was Predominantly Vegetarian

On the path of evolution from chimpanzees and bonobos on one hand, and the genus Homo on the other, in between is Australopithecus, about 3.5 million years ago. Analysis of tooth enamel from Australopithecus remains in South Africa shows that this human ancestor ate very little meat and relied predominantly on plant based food. 

The underlying paper is: Tina Lüdecke, Jennifer N. Leichliter, Dominic Stratford, Daniel M. Sigman, Hubert Vonhof, Gerald H. Haug, Marion K. Bamford, Alfredo Martínez-García. "Australopithecus at Sterkfontein did not consume substantial mammalian meat." 387 (6731) Science 309 (January 2025). DOI: 10.1126/science.adq7315

Austronesian-Papuan People Replaced The First Modern Humans In Wallacea


Wallacea is the ecological region between the Wallace Line and the Lydekker Line (image via Wikipedia at the link). The plants and animals there differ greatly from those to the west (which were connected by land to mainland Asia when sea levels were lower) because neither animals nor 46,000 years of settlers after the first modern humans to cross into it, could cross the roughly 30 miles of deep sea between the regions.

The most basal modern human populations outside Africa, which also have the greatest Denisovan admixture, are the indigenous people of Papua New Guinea and Australia. People from this wave were also present on the islands of the Wallacean Archipelago in Indonesia and lived there undisturbed for about 46,000 years. 

But, when Papuans made contact with and fused with Austronesian sea farers (who originated on the island that is now called Taiwan) around 3500 years ago, contemporaneously with the late Bronze Age in Europe, the resulting fused population replaced the descendants of the first wave of modern humans in the Wallacean Achipelago.
Significance

We present a comprehensive study of the human genetic history of the Wallacean Archipelago and West Papuan regions of Indonesia, including 254 newly sequenced genomes, mostly from previously undocumented populations. In combination with linguistic and archaeological evidence, we show that Wallacean societies were transformed by the spread of genes and languages from West Papua in the past 3,500 y—the same period that Austronesian seafarers were actively mixing with Wallacean and Papuan groups. These migrant groups have largely replaced local Wallacean ancestry sources, challenging common assumptions that Papuan-related ancestry in Wallacea descends from first human migrants enroute to Sahul >50,000 y ago, and suggesting that these ancient movements may not be readily recoverable from modern genetic data alone.

Abstract

The tropical archipelago of Wallacea was first settled by anatomically modern humans (AMH) by 50 thousand years ago (kya), with descendent populations thought to have remained genetically isolated prior to the arrival of Austronesian seafarers around 3.5 kya. 
Modern Wallaceans exhibit a longitudinal countergradient of Papuan- and Asian-related ancestries widely considered as evidence for mixing between local populations and Austronesian seafarers, though converging multidisciplinary evidence suggests that the Papuan-related component instead comes primarily from back-migrations from New Guinea. 
Here, we reconstruct Wallacean population genetic history using more than 250 newly reported genomes from 12 Wallacean and three West Papuan populations and confirm that the vast majority of Papuan-related ancestry in Wallacea (~75 to 100%) comes from prehistoric migrations originating in New Guinea and only a minor fraction is attributable to the founding AMH settlers
Mixing between Papuan and local Wallacean lineages appears to have been confined to the western and central parts of the archipelago and likely occurred contemporaneously with the widespread introduction of genes from Austronesian seafarers—which now comprise between ~40 and 85% of modern Wallacean ancestry—though dating historical admixture events remains challenging due to mixing continuing into the Historical Period. In conjunction with archaeological and linguistic records, our findings point to a dynamic Wallacean population history that was profoundly reshaped by the spread of Papuan genes, languages, and culture in the past 3,500 y.
Gludhug A. Purnomo , Shimona Kealy, Sue O’Connor, Raymond Tobler, et al., "The genetic origins and impacts of historical Papuan migrations into Wallacea" 121 (52) PNAS e2412355121 (December 17, 2024). Hat tip to DDeden.

Tuesday, January 14, 2025

A High Precision Estimate Of The Strong Force Coupling Constant

A new pre-print uses novel methods to make a high precision determination of the strong force coupling constant, at greater precision than all previous determinations combined, which is:

αs(mZ) = 0.11873(56)

The relative uncertainty is one part per 212.


This is important because all strong force (i.e. QCD) calculations rely upon this experimentally determined physical constant.

The Particle Data Group value is 0.1180(9) which is a relative uncertainty of one part per 131 using an error weighted average of all strong force coupling constant measurements.

Monday, January 13, 2025

Radial Migration Of Stars In MOND v. DM

Testable predictions to distinguish between MOND and dark matter theories are valuable.
Multiple studies on radial migration in disc galaxies have proven the importance of the effect of resonances with non-axisymmetric components on the evolution of galactic discs. However, the dynamical effects of classic Newtonian dynamics with dark matter (DM) differ from MOdified Newtonian Dynamics (MOND) and might trigger different radial migration. A thorough analysis of radial migration considering these two gravitational regimes might shed some light on different predictions of DM and MOND theories. We aim to quantitatively and qualitatively compare the effects of resonances and stellar radial migration (churning) in a Milky Way-like (MW-like) galaxy in the DM and MOND regimes. We performed simulations of a MW-like galaxy to analyse the effect of non-axisymmetric structures (galactic bar and spiral arms) considering various parameters of the spiral structure. We conducted a two-dimensional numerical simulation consisting of the integration of 2⋅10^6 stars in a static rotating galactic potential for 6 Gyr. We analysed the change in the star's position, the guiding radius, as well as the frequency phase space. We investigated DM and MOND approaches. The outcome of the simulation shows that the radial migration is much more pronounced in the MOND regime compared to the DM one. Compared to the DM approach, in the MOND regime, we observe up to five times as many stars with a maximum change in the guiding radius of more than 1.5 kpc during the time interval from 2−6 Gyr. Analysis of the frequency phase space reveals that the most prominent resonances in all DM and MOND configurations are the co-rotation resonance with the spiral arms (m=p=1), outer Lindblad resonance with the galactic bar and spiral arms, and the co-rotation resonance (m=2, p=1) with the superposition of the galactic bar and spiral arms, 2Ω=Ωb+Ωsp.
R. Nagy, F. Janák, M. Šturc, M. Jurčík, E. Puha, "Comparing radial migration in dark matter and MOND regimes" arXiv:2501.05924 (January 10, 2025).

Thursday, January 9, 2025

Human Sacrifice In Northern Peru Ca. 500 CE

A new study analyzed the remains of six people at an elite burial in northern coastal Peru in the Moche culture. One boy and one girl were human sacrifices. They were strangled to death which was the norm for human sacrifices in this region. Unexpectedly, the sacrificed children were themselves part of this royal family. The boy was sacrificed with his father. The girl who was sacrificed was the niece of the woman whom she was sacrificed with, who was the highest ranking figure, probably a queen. The graves were the subject of a memorial fire for at least 166 years.

Monday, January 6, 2025

Non-Perturbative GR Strikes Again

Non-perturbative general relativity, which has conventionally been ignored in many circumstances where it is actually relevant, including in modeling ordinary stars.
The general theory of relativity is currently established as the most precise theory of gravity supported by observations, and its application is diverse ranging from astronomy to cosmology, while its application to astrophysics has been restricted only to compact stars due to the assumption that the Newtonian approximation is sufficient for celestial bodies with medium density such as the sun. Surprisingly, the recent research of the author has implied that this long-held assumption is not valid, and that non-perturbative effects significantly change relevant results obtained by Newtonian gravity. In particular, local physical quantities inside the sun are newly predicted to exhibit power law differently from the so-called standard solar model. This surprising result is reviewed including brief discussion of physics behind the discrepancy and a new application of the new mass formula to gas planets.
Shuichi Yokoyama, "Stellar Physics and General Relativity" arXiv:2501.01442 (December 27, 2024) (published in Astronomische Nachrichte).

Thursday, January 2, 2025

Quote Of The Day

They say that science progresses one funeral at a time. But it’s no longer true. Because the first generation of string theorists has raised their students who are now continuing the same stuff. And why would they not, these are cozy jobs, and there is nothing and no one that could stop them. So yeah, Siegfried is right. String theory is not dead. It’s undead, and now walks around like a zombie eating people’s brains.
From Sabine Hossenfelder's Youtube video String Theory Isn’t Dead about the article that Peter Woit discussed here.

Ancient DNA From Siberia As A Source For Modern Populations

Different strains of Siberian ancestry spread east to the New World and west to Scandinavia.
Human populations across a vast area in northern Eurasia, from Fennoscandia to Chukotka, share a distinct genetic component often referred to as the Siberian ancestry. Most enriched in present-day Samoyedic-speaking populations such as Nganasans, its origins and history still remain elusive despite the growing list of ancient and present-day genomes from Siberia. 
Here, we reanalyze published ancient and present-day Siberian genomes focusing on the Baikal and Yakutia, resolving key questions regarding their genetic history. First, we show a long-term presence of a unique genetic profile in southern Siberia, up to 6,000 yr ago, which distinctly shares a deep ancestral connection with Native Americans. Second, we provide plausible historical models tracing genetic changes in West Baikal and Yakutia in fine resolution. Third, the Middle Neolithic individual from Yakutia, belonging to the Belkachi culture, serves as the best source so far available for the spread of the Siberian ancestry into Fennoscandia and Greenland. These findings shed light on the genetic legacy of the Siberian ancestry and provide insights into the complex interplay between different populations in northern Eurasia throughout history.
Haechan Gill, Juhyeon Lee, Choongwon Jeon, "Reconstructing the Genetic Relationship between Ancient and Present-Day Siberian Populations" 16(4) Genome Biology and Evolution evae063 (March 25, 2024) https://doi.org/10.1093/gbe/evae063

Shifts In IQ Over Time

The chart, via Razib Khan, is based upon polygenetic scores calculated based upon ancient DNA.