Continuing with the theme of "archaic hominins admixed with modern humans in Africa leading to their current genetic diversity", I read this paper: Model-based analyses of whole-genome data reveal a complex evolutionary history involving archaic introgression in Central African Pygmies, by PingHsun Hsieh, August E. Woerner, Jeffrey D. Wall, Joseph Lachance, Sarah A. Tishkoff, Ryan N. Gutenkunst and Michael F. Hammer. February 17, 2016, doi: 10.1101/gr.196634.115 Genome Res. 2016. 26: 291-300.
Spoiler alert: the Pygmies, often touted as being diverse, isolated from the rest of H. sapiens, according to this paper, are part of the "...complex human evolutionary history in Africa, which involves at least a single admixture event from an unknown archaic population into the ancestors of AMH, likely within the last 30,000 yr.".
An admixture 30 Kya, after the alleged Out of Africa event means that some archaic group with very diverged genes mixed with modern Humans in Africa and gave them "old" and "diverse" genes, which would, in my opinion, make them seem "more diverse" than the rest of non-African Homo sapiens.
Below I quote from this paper:
" Plagnol and Wall (2006) and Wall et al. (2009) inferred a 5% genetic contribution from a now-extinct taxon to the Niger-Kordofanian Yoruba farmers or their ancestors. Hammer et al. (2011) analyzed DNA sequence data from 61 noncoding loci in three contemporary sub-Saharan African populations. They found that hunter-gatherer African populations, including the Biaka Pygmy, Mbuti Pygmy, and San, contain ∼2% genetic material likely introgressed ∼35 kya from an archaic population that split from the ancestors of modern humans ∼700 kya." (This last citation, Hammer et al, is what I mentioned in my previous post).
"...our inferences suggest recurrent archaic admixture in AMH evolution in Africa, with evidence that at least one such event occurred as recently as ∼9000 yr ago."
"...our results imply that frequent but low-level interbreeding between archaic and modern humans or their ancestors might have occurred in the past in Africa."
Of course the dates are uncertain: "... we found evidence of at least one African archaic admixture event within the last ∼150,000 yr. From our simulation study, this inferred admixture date of ∼9000 (95% C.I.: 1305–28,275) yr ago should be treated as a lower bound".
"However, it is important to point out that archaic introgression need not have been directly into the ancestors of modern Pygmies; rather, it may have resulted from recent gene flow from one or more modern human populations that themselves were recently admixed or that shared recent common ancestry with some unknown archaic hominin(s). The date of the inferred admixture is coincident with the development of agriculture in Africa ∼5–10 kya (Phillipson 2005) and the estimated time of agriculture expansion for Niger-Kodorfanian-speaking farmers ∼7 kya (95% C.I.: 5.7–9.6 kya) (Li et al. 2014). African Pygmies have undergone extensive gene flow with neighboring farmers (Patin et al. 2009; Tishkoff et al. 2009; Jarvis et al. 2012; Hsieh et al. 2016), and recent studies suggest that some Western African populations, including the Niger-Kodorfanian Yoruba farmers from Nigeria, show strong signals of ancient admixture (Plagnol and Wall 2006; Wall et al. 2009). Thus, it is plausible that archaic lineages associated with this inferred admixture event introgressed recently into one or more non-Pygmy African populations, such as the ancestors of African farmers, and subsequently entered the Pygmy population through recent gene flow from these non-Pygmy neighboring groups."
So much for the ancient roots of Pygmies and their archaic Y chromosome and mtDNA... could these have been an introgression from these "ghost" archaic hominins?
Interested in archaic introgression within Africa? Check this post: Archaic MUC7 Haplotype introgression in Africa.
Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2018 by Austin Whittall ©
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