April 30, 2016

More on Kennewick Man

A new technical report re-analyzes the data of Rasmussen et al. study on Kennewick man and confirms that he is related to Native Americans. From the report:
We find the Kennewick sample has the highest shared similarity to Native American populations with the highest values observed being with populations from South America (Figure 7), in line with the observations from Rasmussen et al.
Hopefully this will end the campaign to put him back to the ground. I have added a horizontal line to the new study's Figure 7 to mark the population claiming the skeleton among the huge number considered, showing that there's no particularly strong relationship to it (the strongest connection is at the bottom of the figure).

The Rasmussen et al. and Novembre et al. studies are really science working at its best: simultaneously falsifying claims that Kennewick was some sort of Australoid (or even more implausibly Caucasoid) based on its craniofacial morphology, but not overreaching to validate emotional appeals to make him into an ancestor he wasn't. Thankfully, the way forward is to keep studying Kennewick Man (and modern Native Americans) with ever-better data and techniques which may turn up (who knows?) a real (rather than imagined) ancestral link.

Technical Report: Assessment of the genetic analyses of Rasmussen et al. (2015)

John Novembre, PhD, David Witonsky, Anna Di Rienzo, PhD

The primary aim of the analysis undertaken here (U.S. Army Corps of Engineers, St Louis District Contract #W912P9-16-P-0010) is to provide an independent validation of the genetic evidence underlying a recent publication by Morten Rasmussen and colleagues on July 23rd, 2015, in Nature (Vol 523:455–58). Based on our analysis of the Kennewick Man’s sequence data and Colville tribe genotype data generated by Rasmussen et al., we concur with the findings of the original paper that the sample is genetically closer to modern Native Americans than to any other population worldwide. We carried out several analyses to support this conclusion, including (i) principal component analysis (PCA; Patterson et al. 2006), (ii) unsupervised genetic clustering using ADMIXTURE (Alexander, Novembre, and Lange 2009), (iii) estimation of genetic affinity to modern human populations using f3 and D statistics (Patterson et al. 2012), and (iv) a novel approach based on the geographic distribution of rare variants. Importantly, these distinct analyses, spanning three non-overlapping subsets of the data, are each consistent with Native American ancestry.


April 25, 2016

Bursts in human male demography

From the paper:
When the tree is calibrated with a mutation rate estimate of 0.76 × 10-9 mutations per base pair per year9, the time to the most recent common ancestor (TMRCA) of the tree is ~190,000 years, but we consider the implications of alternative mutation rate estimates below. Of the clades resulting from the four deepest branching events, all but one are exclusive to Africa, and the TMRCA of all non-African lineages (that is, the TMRCA of haplogroups DE and CF) is ~76,000 years (Fig. 1, Supplementary Figs. 18 and 19, Supplementary Table 10, and Supplementary Note). We saw a notable increase in the number of lineages outside Africa ~50–55 kya, perhaps reflecting the geographical expansion and differentiation of Eurasian populations as they settled the vast expanse of these continents. Consistent with previous proposals14, a parsimonious interpretation of the phylogeny is that the predominant African haplogroup, haplogroup E, arose outside the continent. This model of geographical segregation within the CT clade requires just one continental haplogroup exchange (E to Africa), rather than three (D, C, and F out of Africa). Furthermore, the timing of this putative return to Africa—between the emergence of haplogroup E and its differentiation within Africa by 58 kya—is consistent with proposals, based on non–Y chromosome data, of abundant gene flow between Africa and nearby regions of Asia 50–80 kya15.
I've long argued for the Y-chromosome haplogroup E migration into Africa and it is nice to see this common-sense interpretation finally adopted. Too much focus has been placed on figuring out which routes modern humans took out of Africa, and not at all to figure out how Eurasian males came to overwhelm the African Y-chromosome gene pool so decisively. The Eurasian migration into Africa must have taken place in the ~70-60kya window, constrained by the D/E split and  the deepest intra-African E splits. I think that the Out-of-Arabia scenario I outlined in 2012 continues to make a lot of sense. It would be awesome to get data from the first Later Stone Age people from Africa which are probably the best bet to trace this migration from Eurasia into Sub-Saharan Africa.

Nature Genetics (2016) doi:10.1038/ng.3559

Punctuated bursts in human male demography inferred from 1,244 worldwide Y-chromosome sequences

G David Poznik et al.

We report the sequences of 1,244 human Y chromosomes randomly ascertained from 26 worldwide populations by the 1000 Genomes Project. We discovered more than 65,000 variants, including single-nucleotide variants, multiple-nucleotide variants, insertions and deletions, short tandem repeats, and copy number variants. Of these, copy number variants contribute the greatest predicted functional impact. We constructed a calibrated phylogenetic tree on the basis of binary single-nucleotide variants and projected the more complex variants onto it, estimating the number of mutations for each class. Our phylogeny shows bursts of extreme expansion in male numbers that have occurred independently among each of the five continental superpopulations examined, at times of known migrations and technological innovations.


April 24, 2016

Jewish and Indian ancestry in the Bene Israel

PLoS ONE 11(3): e0152056. doi:10.1371/journal.pone.0152056

The Genetics of Bene Israel from India Reveals Both Substantial Jewish and Indian Ancestry
Yedael Y. Waldman , Arjun Biddanda , Natalie R. Davidson, Paul Billing-Ross, Maya Dubrovsky, Christopher L. Campbell, Carole Oddoux, Eitan Friedman, Gil Atzmon, Eran Halperin, Harry Ostrer, Alon Keinan

The Bene Israel Jewish community from West India is a unique population whose history before the 18th century remains largely unknown. Bene Israel members consider themselves as descendants of Jews, yet the identity of Jewish ancestors and their arrival time to India are unknown, with speculations on arrival time varying between the 8th century BCE and the 6th century CE. Here, we characterize the genetic history of Bene Israel by collecting and genotyping 18 Bene Israel individuals. Combining with 486 individuals from 41 other Jewish, Indian and Pakistani populations, and additional individuals from worldwide populations, we conducted comprehensive genome-wide analyses based on FST, principal component analysis, ADMIXTURE, identity-by-descent sharing, admixture linkage disequilibrium decay, haplotype sharing and allele sharing autocorrelation decay, as well as contrasted patterns between the X chromosome and the autosomes. The genetics of Bene Israel individuals resemble local Indian populations, while at the same time constituting a clearly separated and unique population in India. They are unique among Indian and Pakistani populations we analyzed in sharing considerable genetic ancestry with other Jewish populations. Putting together the results from all analyses point to Bene Israel being an admixed population with both Jewish and Indian ancestry, with the genetic contribution of each of these ancestral populations being substantial. The admixture took place in the last millennium, about 19–33 generations ago. It involved Middle-Eastern Jews and was sex-biased, with more male Jewish and local female contribution. It was followed by a population bottleneck and high endogamy, which can lead to increased prevalence of recessive diseases in this population. This study provides an example of how genetic analysis advances our knowledge of human history in cases where other disciplines lack the relevant data to do so.


April 14, 2016

Periods of human activity in Chauvet-Pont d'Arc cave

PNAS DOI: doi: 10.1073/pnas.1523158113

A high-precision chronological model for the decorated Upper Paleolithic cave of Chauvet-Pont d’Arc, Ardèche, France

Anita Quiles et al.

Radiocarbon dates for the ancient drawings in the Chauvet-Pont d’Arc Cave revealed ages much older than expected. These early ages and nature of this Paleolithic art make this United Nations Educational, Scientific and Cultural Organization (UNESCO) site indisputably unique. A large, multidisciplinary dating program has recently mapped the anthropological evolution associated with the cave. More than 350 dates (by 14C, U-Th, TL and 36Cl) were obtained over the last 15 y. They include 259 radiocarbon dates, mainly related to the rock art and human activity in the cave. We present here more than 80 previously unpublished dates. All of the dates were integrated into a high-precision Bayesian model based on archaeological evidence to securely reconstruct the complete history of the Chauvet-Pont d’Arc Cave on an absolute timescale. It shows that there were two distinct periods of human activity in the cave, one from 37 to 33,500 y ago, and the other from 31 to 28,000 y ago. Cave bears also took refuge in the cave until 33,000 y ago.


April 10, 2016

Nubian assemblages from the Negev

Nubian assemblages from the Levant are quite important because they provide an intermediate link (along land routes) between those from Africa and Arabia. It's also more difficult now to consider the Arabian finds as a limited event without broader implications about modern human dispersals. From the paper:
Mapping the earliest dated sites that contain a Nubian component does not permit an unequivocal identification of a region of origin for the Nubian Technology.
Quaternary International doi:10.1016/j.quaint.2016.02.008

“Diffusion with modifications”: Nubian assemblages in the central Negev highlands of Israel and their implications for Middle Paleolithic inter-regional interactions

Mae Goder-Goldberger, Natalia Gubenko, Erella Hovers

Nubian Levallois cores, now known from sites in eastern Africa, the Nile Valley and Arabia, have been used as a material culture marker for Upper Pleistocene dispersals of hominins out of Africa. The Levantine corridor, being the only land route connecting Africa to Eurasia, has been viewed as a possible dispersal route. We report here on lithic assemblages from the Negev highlands of Israel that contain both Levallois centripetal and Nubian-type cores. Wetter conditions over the Sahara and Negev deserts during MIS 6a–5e provided a generally continuous environmental corridor into the Levant that enabled the dispersal of hominin groups bearing the Nubian variant of prepared core technologies. The Negev assemblages draw renewed attention to the place of the Levant as one of the dispersal routes out of Africa during the Late Pleistocene and could suggest that processes of human dispersals and cultural diffusion resulted in the spread of Nubian technology across eastern Africa, the western Sahara and the Nile Valley, the southern Levant and Arabia.


April 07, 2016

Neandertal Y-chromosome (finally)

It's been six years since the publication of the draft Neandertal genome, and one piece of the puzzle that's always been missing is the Neandertal Y-chromosome (unfortunately most of the Neandertals yielding data were female). But, the wait is finally over, with the first publication of Neandertal Y-chromosome data.

AJHG Volume 98, Issue 4, p728–734, 7 April 2016

The Divergence of Neandertal and Modern Human Y Chromosomes

Fernando L. Mendez, G. David Poznik, Sergi Castellano, Carlos D. Bustamante

Sequencing the genomes of extinct hominids has reshaped our understanding of modern human origins. Here, we analyze ∼120 kb of exome-captured Y-chromosome DNA from a Neandertal individual from El Sidrón, Spain. We investigate its divergence from orthologous chimpanzee and modern human sequences and find strong support for a model that places the Neandertal lineage as an outgroup to modern human Y chromosomes—including A00, the highly divergent basal haplogroup. We estimate that the time to the most recent common ancestor (TMRCA) of Neandertal and modern human Y chromosomes is ∼588 thousand years ago (kya) (95% confidence interval [CI]: 447–806 kya). This is ∼2.1 (95% CI: 1.7–2.9) times longer than the TMRCA of A00 and other extant modern human Y-chromosome lineages. This estimate suggests that the Y-chromosome divergence mirrors the population divergence of Neandertals and modern human ancestors, and it refutes alternative scenarios of a relatively recent or super-archaic origin of Neandertal Y chromosomes. The fact that the Neandertal Y we describe has never been observed in modern humans suggests that the lineage is most likely extinct. We identify protein-coding differences between Neandertal and modern human Y chromosomes, including potentially damaging changes to PCDH11Y, TMSB4Y, USP9Y, and KDM5D. Three of these changes are missense mutations in genes that produce male-specific minor histocompatibility (H-Y) antigens. Antigens derived from KDM5D, for example, are thought to elicit a maternal immune response during gestation. It is possible that incompatibilities at one or more of these genes played a role in the reproductive isolation of the two groups.


April 01, 2016

Zhiren cave human remains: 116-106 ka old

Quaternary International doi:10.1016/j.quaint.2015.12.088

The age of human remains and associated fauna from Zhiren Cave in Guangxi, southern China

Yanjun Cai et al.

Zhiren Cave in southern China is an important site for the study of the origin and the environmental background of early modern humans. The combination of Elephas kiangnanensis, Elephas maximus, and Megatapirus augustus, indicates an early representative of the typical Asian elephant fauna. Previous U-series dating of flowstone calcite has pinpointed an upper age limit for the fossils of about 100 ka. In order to achieve a better comprehension of the chronology of the modern human and contemporaneous faunal assemblage, paleomagnetic, stratigraphic, and optically stimulated luminescence (OSL) dating methods have been applied to the cave sediments. Paleomagnetic analyses reveal that there is a reversed polarity excursion below the fossiliferous layer. This excursion can be regarded as the Blake excursion event, given the U-series ages of the overlying flowstone calcite, the OSL measurements, the virtual geomagnetic pole (VGP) path of the excursion, the two reverse polarity zones within this excursion event, and the characteristic of the fauna assemblage. The human remains and mammalian fauna assemblage can be bracketed to 116–106 ka. Application of OSL dating leads to erroneous ages, largely due to the uncertainty associated with the estimation on the dose rates.