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

Study: Neandertal Speech and Language Abilities Like Modern Humans

Science Daily has a story on Neandertal speech.  Work by Dan Didiu and Stephen Levinson suggests that Neandertals and modern humans share a common ancestry with regard to the use of language.  Science Daily writes:

Dediu and Levinson review all these strands of literature and argue that essentially modern language and speech are an ancient feature of our lineage dating back at least to the most recent ancestor we shared with the Neandertals and the Denisovans (another form of humanity known mostly from their genome). Their interpretation of the intrinsically ambiguous and scant evidence goes against the scenario usually assumed by most language scientists, namely that of a sudden and recent emergence of modernity, presumably due to a single -- or very few -- genetic mutations. This pushes back the origins of modern language by a factor of 10 from the often-cited 50 or so thousand years, to around a million years ago -- somewhere between the origins of our genus, Homo, some 1.8 million years ago, and the emergence of Homo heidelbergensis. This reassessment of the evidence goes against a saltationist scenario where a single catastrophic mutation in a single individual would suddenly give rise to language, and suggests that a gradual accumulation of biological and cultural innovations is much more plausible..

I am still a bit “iffy” on the whole “common ancestor of modern humans and Neandertals” thing since some are trying to argue for a common ancestor based on the material from the Gran Dolina, in Spain, and it sure as all get out looks like modern humans originated in Northeast Africa at, or near, Herto. I have a tendency to think that there was a good deal of panmixia throughout Europe and north Africa.  Otherwise, we are required to believe that there was a species split at H. antecessor into what became modern humans (how'd they get to north Africa?) on one side and Neandertals on the other and that, some 700 to 720 thousand years later, emerging moderns and Neandertals encountered one another and interbred.  That is overly simplistic, I am sure but it seems far-fetched.  It seems easier to argue that the H. antecessor material represents an archaic Homo sapiens population that was the precursor (or something like it was) to later archaics, such as Petralona and Atapuerca, out of which Neandertals came.  Then the Neandertals interbred with the north-moving moderns and somewhere in there, the Denisova population split off.  The panmixia in Europe, western Asia and Russia explains why moderns have both Neandertal and Denisovan genes, along with the modern genes that originated in North Africa.  Subsequent swamping of the archaic genome led to the demise of both the Neandertals and Denisovans.