January 26, 2016

History of extant populations of India

The five components they speak of are ANI, ASI, AAA (Ancestral Austro-Asiatic), ATB (Ancestral Tibeto-Burman), and a distinct fifth ancestry in the Andaman archipelago.

The differentiation of the four main components seems clear enough on the figure (left). The big question is how and in what order the different components got into India. I would wager that ASI was first and I modify my New Year's wish to ask for some ancient DNA from India too.

An interesting bit from the paper:
...that the practice of endogamy was established almost simultaneously, possibly by decree of the rulers, in upper-caste populations of all geographical regions, about 70 generations before present, probably during the reign (319–550 CE) of the ardent Hindu Gupta rulers
How plausible is that to anyone familiar with Indian history?

PNAS doi: 10.1073/pnas.1513197113

Genomic reconstruction of the history of extant populations of India reveals five distinct ancestral components and a complex structure

Analabha Basu, Neeta Sarkar-Roya, and Partha P. Majumder

India, occupying the center stage of Paleolithic and Neolithic migrations, has been underrepresented in genome-wide studies of variation. Systematic analysis of genome-wide data, using multiple robust statistical methods, on (i) 367 unrelated individuals drawn from 18 mainland and 2 island (Andaman and Nicobar Islands) populations selected to represent geographic, linguistic, and ethnic diversities, and (ii) individuals from populations represented in the Human Genome Diversity Panel (HGDP), reveal four major ancestries in mainland India. This contrasts with an earlier inference of two ancestries based on limited population sampling. A distinct ancestry of the populations of Andaman archipelago was identified and found to be coancestral to Oceanic populations. Analysis of ancestral haplotype blocks revealed that extant mainland populations (i) admixed widely irrespective of ancestry, although admixtures between populations was not always symmetric, and (ii) this practice was rapidly replaced by endogamy about 70 generations ago, among upper castes and Indo-European speakers predominantly. This estimated time coincides with the historical period of formulation and adoption of sociocultural norms restricting intermarriage in large social strata. A similar replacement observed among tribal populations was temporally less uniform.


January 16, 2016

Humans in the central Siberian Arctic ~45,000 years ago

The lack of such northerly sites prior to 45,000 years ago makes it quite likely that this mammoth kill was made by modern humans (it would be quite a coincidence if it was made by Neandertals at the same time as the expansionary Homo sapiens make their appearance all over the rest of Eurasia). If this is right, it's quite remarkable that by the mid to late 40,000s, modern humans were at ease from the equator to the arctic and from Europe to the remotest parts of Asia.

Science 15 Jan 2016:
Vol. 351, Issue 6270, pp. 260-263

Early human presence in the Arctic: Evidence from 45,000-year-old mammoth remains

Vladimir V. Pitulko, Alexei N. Tikhonov et al.

Archaeological evidence for human dispersal through northern Eurasia before 40,000 years ago is rare. In west Siberia, the northernmost find of that age is located at 57°N. Elsewhere, the earliest presence of humans in the Arctic is commonly thought to be circa 35,000 to 30,000 years before the present. A mammoth kill site in the central Siberian Arctic, dated to 45,000 years before the present, expands the populated area to almost 72°N. The advancement of mammoth hunting probably allowed people to survive and spread widely across northernmost Arctic Siberia.


January 08, 2016

Helicobacter pylori in the Iceman

Science 8 January 2016:
Vol. 351 no. 6269 pp. 162-165

The 5300-year-old Helicobacter pylori genome of the Iceman
Frank Maixner1,*,†, Ben Krause-Kyora2,†, Dmitrij Turaev3,†, Alexander Herbig4,5, et al.

The stomach bacterium Helicobacter pylori is one of the most prevalent human pathogens. It has dispersed globally with its human host, resulting in a distinct phylogeographic pattern that can be used to reconstruct both recent and ancient human migrations. The extant European population of H. pylori is known to be a hybrid between Asian and African bacteria, but there exist different hypotheses about when and where the hybridization took place, reflecting the complex demographic history of Europeans. Here, we present a 5300-year-old H. pylori genome from a European Copper Age glacier mummy. The “Iceman” H. pylori is a nearly pure representative of the bacterial population of Asian origin that existed in Europe before hybridization, suggesting that the African population arrived in Europe within the past few thousand years.


January 06, 2016

Even more Anatolian Neolithic genomes

Recently I proclaimed the problem of "Neolithization of Europe" to be "done", but it doesn't hurt to have more confirmation as this new paper does. The Anatolian data is from a different site than those used by Mathieson et al. and Hofmanová, Kreutzer et al. albeit still in the extreme northwest of Asia Minor. Nonetheless, the individual from Kumtepe doesn't seem to carry any major surprises, so "Neolithization of Europe" remains "done".

Current Biology http://dx.doi.org/10.1016/j.cub.2015.12.019

Genomic Evidence Establishes Anatolia as the Source of the European Neolithic Gene Pool 

Ayça Omrak et al.

Anatolia and the Near East have long been recognized as the epicenter of the Neolithic expansion through archaeological evidence. Recent archaeogenetic studies on Neolithic European human remains have shown that the Neolithic expansion in Europe was driven westward and northward by migration from a supposed Near Eastern origin [ 1–5 ]. However, this expansion and the establishment of numerous culture complexes in the Aegean and Balkans did not occur until 8,500 before present (BP), over 2,000 years after the initial settlements in the Neolithic core area [ 6–9 ]. We present ancient genome-wide sequence data from 6,700-year-old human remains excavated from a Neolithic context in Kumtepe, located in northwestern Anatolia near the well-known (and younger) site Troy [ 10 ]. Kumtepe is one of the settlements that emerged around 7,000 BP, after the initial expansion wave brought Neolithic practices to Europe. We show that this individual displays genetic similarities to the early European Neolithic gene pool and modern-day Sardinians, as well as a genetic affinity to modern-day populations from the Near East and the Caucasus. Furthermore, modern-day Anatolians carry signatures of several admixture events from different populations that have diluted this early Neolithic farmer component, explaining why modern-day Sardinian populations, instead of modern-day Anatolian populations, are genetically more similar to the people that drove the Neolithic expansion into Europe. Anatolia’s central geographic location appears to have served as a connecting point, allowing a complex contact network with other areas of the Near East and Europe throughout, and after, the Neolithic.


January 01, 2016

Happy New Year 2016

Last year I wished for ancient African DNA and I got my wish.
This year I wish for some ancient East Asian DNA. It's quite an embarrassment that hundreds of ancient European genomes have been published, but only a single Chromosome 21 from East Asia.