Tuesday, August 15, 2017

Links: Human Evolution

Sharing links to interesting articles I have read in the past few months. Better understanding of human evolution is being driven by a) New fossil finds giving valuable insights into morphologic variation and geography, b) DNA analysis of both modern and extinct populations giving us an understanding of genealogical relationships and migration histories and c) better absolute dating of fossils that constraint evolutionary scenarios.

1) What Are Our Best Clues To The Evolution Of Fire-Making? Anthropologist Barbara J King examines the physical evidence of fire making by ancient hominins and presents speculations on how natural fires may have played a role in hominin cultural evolution.

2) A world map of Neanderthal and Denisovan ancestry in modern humans- Phys.Org. " There are certain classes of genes that modern humans inherited from the archaic humans with whom they interbred, which may have helped the modern humans to adapt to the new environments in which they arrived," says senior author David Reich, a geneticist at Harvard Medical School and the Broad Institute. "On the flip side, there was negative selection to systematically remove ancestry that may have been problematic from modern humans. We can document this removal over the 40,000 years since these admixtures occurred."

3) Three new discoveries in a month rock our African origins- Prof. John Hawks on new fossil dating of hominin fossils from Morocco and evidence from archaic DNA from S. Africa that complicates the African story of the origins of Homo sapiens. The scenario suggested here is that Homo sapiens did not evolve due to changes in a population which was genetically isolated from other Pleistocene African hominin groups. Rather there was a pan-African gene flow. This is multi-regionalism within Africa.

4) Out of North Africa- Dienekes argues the exact opposite.. that the Morocco fossils imply that Homo sapiens evolved in north Africa from a reproductively isolated population and that multi-regionalism is wrong.

5) Features of the Grecian ape raise questions about early hominins- Did the hominin clade evolve in Europe and not Africa? Prof. John Hawk's critique of a recent paper suggesting that view. He cautions that convergent evolution is common among different hominin lineages. A single feature, such as the mandible used in this paper, cannot indicate relationships.

6) Early modern humans in Sumatra before the Toba eruption- Steve Drury in Earth Pages summarizes new evidence that indicates early ( more than 70,000 years ago) migration of Homo sapiens into SE Asia. .." Together with the dating of the earliest Australians the Sumatran evidence is at odds with the view, widely held by palaeoanthropologists, that the ‘Out of Africa’ exodus began by crossing the Straits of Bab el Mandab between 74 and 58 ka when global sea-level fell markedly during marine oxygen-isotope Stage 4 (MIS4). A problem with that hypothesis has been that climatic and ecological conditions in southern Asia during MIS4 were unfavourable. But is seems that modern humans were already there and capable of adapting to both the climate shift and to the devastation undoubtedly caused by Toba."

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