Full Khoi-San genomes published

Found via Science Daily.

Stephan C. Schuster, Web Miller et al., Complete Khoisan and Bantu genomes from southern Africa. Nature 2010. Open access.

Four Khoi-San elders and archbishop Desmond Tutu (representing the rest of humankind and in particular South African Bantus) were scanned for their full genomes in order to overcome the limitations of the HapMap samples. The fact that any two Khoi-San are more different among them than any two Eurasians underlines the great importance of this extension to the human genetic database.

Most of the interesting details are available at the supplementary material (PDF). Among them, what most called my attention was the age estimates for mitochondrial DNA lineages (table 5).

They use a calibration point at the MRCA of H. sapiens and H. neanderthalensis, which is estimated at 660 Ka ago, with CI of 520-800 Ka (following Green 2008), however Noonan 2006 had an older estimate of 706 Ka ago (CI: 468-1015 Ka) and I have good archaeological reasons to consider an age of c. 900 Ka ago.

Hence I will review here Schuster's and Miller's median estimates but also emphasize the oldest CI dates, which I believe are closer to reality:

The Human MRCA ("mitochondrial Eve") is now dated to 205 Ka ago (or 296 Ka with the oldest CI, whch I think is best).

For the particular mtDNA lineages, the dates are:

• L0 159 (232) Ka
• L0d 107 (170) Ka
• L0a'b'f'k 148 Ka (no CI)
• L0k 79 (122) Ka
• L0a'b'f 119 (176) Ka
• L0f 94 (140) Ka
• L0a 61 (95) Ka
• L1''6 173 (250) Ka
• L3 96 (137) Ka

Dates in parenthesis are all oldest CIs, which I fear could still be slightly younger than archaeological realism demands.

The latter date, L3, is particularly important because it signals the beginning of the Out of Africa episode. A date of c. 137 Ka ago (or even older) would be roughly coincident with the colonization of some of Palestine by H. sapiens (Skhul, Qafzeh) and could be speaking of such an old migrational event, maybe ratified by some unclear elements in the archaeology of India (see also Petraglia 2007), China and Japan (and also Crete maybe but this one without continuity).

In the depths of the great-great-...-great-grandmother

A new study, by D.M. Behar et al., on the oldest human maternal lineages (mtDNA) has seen light at the AJHG (subscribers only - but will be open access in six months). As I have only access to the abstract and to the news published here and there, I can only comment so much but certainly it is great that mitochondrial genetics and specially old African ones (at the root of everyting else) are been given due attention.

The abstract is rather cryptic:

Both the tree phylogeny and coalescence calculations suggest that Khoisan matrilineal ancestry diverged from the rest of the human mtDNA pool 90,000-150,000 years before present (ybp) and that at least five additional, currently extant maternal lineages existed during this period in parallel. Furthermore, we estimate that a minimum of 40 other evolutionarily successful lineages flourished in sub-Saharan Africa during the period of modern human dispersal out of Africa approximately 60,000-70,000 ybp. Only much later, at the beginning of the Late Stone Age, about 40,000 ybp, did introgression of additional lineages occur into the Khoisan mtDNA pool. This process was further accelerated during the recent Bantu expansions. Our results suggest that the early settlement of humans in Africa was already matrilineally structured and involved small, separately evolving isolated populations.

But the news are written in a more spectacular style, suggesting that humankind was about to split in two separate species, one in southern and the other in equatorial Africa, due to isolation from each other. But later both groups came into contact again and the unity of the species was re-estabilished.

As far as I can tell this is related to the antiquity of L0, specific of Khoisan peoples of southern Africa.
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Update: Science daily has an article with a maybe less dramatic approach to the same paper: Early Human Populations Evolved Separately For 100,000 Years. Here an excerpt:

Recent paleoclimatological data suggests that Eastern Africa went through a series of massive droughts between 135,000-90,000 years ago. It is possible that this climatological shift contributed to the population splits. What is surprising is the length of time the populations were separate - as much as half of our entire history as a species.

The timing of these events coincides with the onset of the Late Stone Age in Africa, a change in material culture that many archaeologists believe heralds the beginning of fully modern human behavior, including abstract thought and complex spoken language.