Short IBD segments shared between Humans, Neanderthals and Denisovans in Africa and Eurasia

[Kale]

What

[Longbowman]

where do buttcheeks come into it?

[Kale]

where do buttcheeks come into it?

You got it all backwards.

[Argang]

A new study proposes that Neanderthals were much less heterozygous and had a smaller gene pool than modern humans.



They also did a PCA comparing Neanderthals and Denisovan to modern humans from Europe, Africa and Asia.

Principal components 1 and 2 contain 38.04% and 14.65% of the total variation respectively and seem to mark species differences, Sapiens populations cluster together, Neanderthals cluster together and Denisovan is on its own.

PC3 and PC4 represent 8.96% and 6.06% of the variation and there we start seeing significant differences between modern humans. Neanderthals and Denisovan still are separate from modern humans but much closer to Europeans and Asians than to Africans.
Assuming the supplementary information uses the same three populations for PCA's and homozygosity tests, it seems that the reference individuals for Africa are Mandenka, Dinka and Yoruba, for Europe they're French, Sardinian and Italian-American, and for Asia Han, Dai and Papuan. It would have been nice to have North European, South Asian and Amerindian references but w/e

source:
http://www.pnas.org/content/suppl/20...38111.sapp.pdf

[Argang]

This study suggests Eurasians have also admixture from pre-Neanderthal archaic hominins.

http://arxiv.org/abs/1404.7766

Introgressions from Neanderthals and Denisovans were detected in modern humans. Introgressions from other archaic hominins were also implicated, however, identification of which poses a great technical challenge. Here, we introduced an approach in identifying introgressions from all possible archaic hominins in Eurasian genomes, without referring to archaic hominin sequences. We focused on mutations emerged in archaic hominins after their divergence from modern humans (denoted as archaic-specific mutations), and identified introgressive segments which showed significant enrichment of archaic-specific mutations over the rest of the genome. Furthermore, boundaries of introgressions were identified using a dynamic programming approach to partition whole genome into segments which contained different levels of archaic-specific mutations. We found that detected introgressions shared more archaic-specific mutations with Altai Neanderthal than they shared with Denisovan, and 60.3% of archaic hominin introgressions were from Neanderthals. Furthermore, we detected more introgressions from two unknown archaic hominins whom diverged with modern humans approximately 859 and 3,464 thousand years ago. The latter unknown archaic hominin contributed to the genomes of the common ancestors of modern humans and Neanderthals. In total, archaic hominin introgressions comprised 2.4% of Eurasian genomes. Above results suggested a complex admixture history among hominins. The proposed approach could also facilitate admixture research across species.

If that's right, Mbuti and Yoruba reinforce their status as purest Homo Sapiens I quess.