Neandertals and Modern Humans Had Longer Period of "Intimate" Contact

New research suggests that the earliest time that Neandertals and moderns humans got jiggy with it was around 100,000 years ago.  This is a break from the conventional (if you can call an argument five years old “conventional”) argument that most of these interactions occurred between 50 and 60 thousand years ago.  According to Jennifer Viegas, in Discovery News:

Remains of a Neanderthal woman who lived around 100,000 years ago in the Altai Mountains of Siberia reveal that human and Neanderthals mated much earlier than previously thought.

One or more of her relatives were actually humans, a new study shows.

It has been known that Neanderthals contributed DNA to modern humans, so people today of European and Asian descent retain Neanderthal DNA in their genomes, but the Neanderthal woman offers the first evidence that gene flow from interbreeding went from modern humans into Neanderthals as well.

The study, published in the journal Nature¹, "is also the first to provide genetic evidence of modern humans outside Africa as early as 100,000 years ago," Sergi Castellano, who co-led the study and is a researcher at the Max Planck Institute for Evolutionary Anthropology, told Discovery News.

Given the now closely intertwined histories of Neanderthals and Homo sapiens, Castellano added that "it is better to refer to Neanderthals and modern humans as two different human groups, one archaic and one modern, and not different species."

This last point is hotly contested. The prevailing wisdom is that they were two different species that could interbreed when they came into contact but had their own stable genomes. If the time of contact can be stretched from 100 kya to 50 kya, though, it lends more credence to the ideas that their lifestyles were largely compatible, especially given the new information from Schöningen, which seems to indicate complex patterns of subsistence emerging as early as 300 kya. Oddly, missing from the story is that the researchers suggest that these hybridizations may have occurred in the ancestors of the Neandertals in Southwest Asia, not northern Europe.  This would one of the natural corridors for people coming out of Africa, although recent research has focused on the Arabian peninsula for that migration.

¹Kuhlwilm, Martin, Gronau, Ilan, Hubisz, Melissa J., de Filippo, Cesare, Prado-Martinez, Javier, Kircher, Martin, Fu, Qiaomei, Burbano, Hernán A., Lalueza-Fox, Carles, de la Rasilla, Marco, Rosas, Antonio, Rudan, Pavao, Brajkovic, Dejana, Kucan, Željko, Gušic, Ivan, Marques-Bonet, Tomas, Andrés, Aida M., Viola, Bence, Pääbo, Svante, Meyer, Matthias, Siepel, Adam, & Castellano, Sergi. (2016). Ancient gene flow from early modern humans into Eastern Neanderthals. Nature, 530(7591), 429-433.
http://dx.doi.org/10.1038/nature16544

Neandertal/Modern Human Hybridization in North Africa?

That is the focus of a new paper in PLoS ONE by Sanchez and colleagues.  Using 780 thousand single nucleotide polymorphisms of 125 individuals from populations in North Africa, they write:

We found that North African populations have a significant excess of derived alleles shared with Neandertals, when compared to sub-Saharan Africans. This excess is similar to that found in non-African humans, a fact that can be interpreted as a sign of Neandertal admixture. Furthermore, the Neandertal's genetic signal is higher in populations with a local, pre-Neolithic North African ancestry. Therefore, the detected ancient admixture is not due to recent Near Eastern or European migrations. Sub-Saharan populations are the only ones not affected by the admixture event with Neandertals.

Well, raise my rent! When we analyzed the modern human remains in the Near East using canonical variates analysis, we found that they showed more of a similarity with North African archaics than they did Neandertals and that this supported a model of a general northern migration of North Africans into the Levant between 100 and 200 thousand years ago. I will be interested to see the reaction to this from the morphologists.

Ironically, the bulk of the evidence supporting the admixture of modern humans and Neandertals has always been based on the fossil record, while the genetic evidence has traditionally been used to argue for a recent African origin. It is interesting to see all of the genetic studies that have turned the tables. There is not a specific level of admixture at which point you can say "hey, these are the same species," but the studies continue to come out suggesting that admixture was taking place wherever these two groups intermingled and that there do not seem to have been biological imperatives to mate.  They simply decided to do so.  Remember the sage words of J. Lawrence Angel: "When two groups of people meet, they may fight but they willl always mate."