New DNA Analysis Allows for Greater Understanding of Modern Human Prehistory

From Science Daily:

A University of Utah-led team developed a new method for analyzing DNA sequence data to reconstruct the early history of the archaic human populations. They revealed an evolutionary story that contradicts conventional wisdom about modern humans, Neanderthals and Denisovans.

The study¹ found that the Neanderthal-Denisovan lineage nearly went extinct after separating from modern humans. Just 300 generations later, Neanderthals and Denisovans diverged from each other around 744,000 years ago. Then, the global Neanderthal population grew to tens of thousands of individuals living in fragmented, isolated populations scattered across Eurasia.

"This hypothesis is against conventional wisdom, but it makes more sense than the conventional wisdom." said Alan Rogers, professor in the Department of Anthropology and lead author of the study that will publish online on August 7, 2017 in the Proceedings of the National Academy of Sciences.

As the authors note, there is mounting evidence of a migration from Africa to Europe, likely by way of the Strait of Gibraltar, in which Acheulean stone tools are introduced by a group which became known as Homo heidelbergensis.  This group, subsequently, split, likely gave rise to the Neandertals  and the Denisovans a bit later.  Then, a second wave of migrations around 90 to 100 ky happened, during which there was hybridization between Neandertals, moderns and Denisovans.

We live in a time where we now have the genomes of archaic Africans, Eurasians, Neandertals, Denisovans and early moderns and can compare them using site pattern analysis.  These authors found that

• In contrast to previous studies, this one indicates that Neandertal population size was large, on the order of tens of thousands of people, in isolated populations
• The split between the Neandertals and Denisovans was early, on the order of 744 thousand years ago.  
• By the time you find these hominins in the fossil record, they had already split from the Denisovans, which explains why the Atapuerca Sima De Los Huesos hominins resemble Neandertals more than Denisovans.
• Therefore, Neandertal features are thought to have emerged over a long period of time in Europe. 

This analysis will help us rethink our understanding of the fossil material from Gran Dolina, which now likely represents a population from which both the Denisovans and Neandertals split.  This makes sense, given the general, non-derived nature of the fossil material from there.  Things are slowly (maybe?) falling into place.

¹Alan R. Rogers, Ryan J. Bohlender, and Chad D. Huff. Early history of Neanderthals and Denisovans. PNAS, August 2017 DOI: 10.1073/pnas.1706426114