Convoluted human evolution: Neanderthal split (Introduction)

by David Turell @, Wednesday, March 16, 2016, 23:03 (614 days ago) @ David Turell

Apparently about 430,000 years ago, or maybe more:

http://www.nature.com/news/oldest-ancient-human-dna-details-dawn-of-neanderthals-1.1955...

"The remains are known as the Sima hominins because they were found in Sima de los Huesos (Spanish for ‘pit of bones'), a 13-metre-deep shaft in Spain's Atapuerca mountains. Few ancient sites are as important or intriguing as Sima, which holds the remains of at least 28 individuals, along with those of dozens of cave bears and other animals. The hominins might have plummeted to their death, but some researchers think they were deliberately buried there.

"The Sima hominin skulls have the beginnings of a prominent brow ridge, as well as other traits typical of Neanderthals. But other features, and uncertainties around their age — some studies put them at 600,000 years old, others closer to 400,000 — convinced many researchers that they might instead belong to an older species known as Homo heidelbergensis.

***

"The nuclear DNA, Meyer's team reports in Nature on 14 March, shows that the Sima hominins are in fact early Neanderthals. And its age suggests that the early predecessors of humans diverged from those of Neanderthals between 550,000 and 765,000 years ago — too far back for the common ancestors of both to have been Homo heidelbergensis, as some had posited.

"Researchers should now be looking for a population that lived around 700,000 to 900,000 years ago, says Martinón-Torres. She thinks that Homo antecessor, known from 900,000-year-old remains from Spain, is the strongest candidate for the common ancestor, if such specimens can be found in Africa or the Middle East.

"The team's latest mitochondrial sequences, meanwhile, again confirm the puzzling link between the Sima hominins and the Denisovans. Meyer suggests that the ancestors of the two groups carried mitochondrial DNA that is reflected in both — but which is not present in later Neanderthals. This elimination could have happened by chance, but Meyer now favours the hypothesis that an as yet unknown species from Africa migrated to Eurasia and bred with Neanderthals, replacing the mitochondrial DNA lineages. (Supporting this idea, stone-tool technologies spread from Africa to Eurasia around half a million years ago, and again 250,000 years ago)."

Comment: Still a bush of hominins, sorting out the timing of the branches.


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