Large Denisovan Fossil Discovered

Nature News is reporting on a jaw fragment that has been discovered on the Tibetan Plateau that is close to 160,000 years old. From the story:

The research marks the first time an ancient human has been identified solely through the analysis of proteins. With no usable DNA, scientists examined proteins in the specimen’s teeth, raising hopes that more fossils could be identified even when DNA is not preserved...

Until now, everything scientists have learnt about Denisovans has come from a handful of teeth and bone fragments from Denisova Cave in Russia’s Altai Mountains. DNA from these remains revealed that the Denisovans were a sister group to Neanderthals, both descending from a population that split away from modern humans about 550,00–765,000 years ago. And at Denisova Cave, the two groups seem to have met and interbred: a bone fragment described last year belonged an ancient-human hybrid individual who had a Denisovan father and Neanderthal mother.

One of the most important aspects of the study is that it opens the door to answering questions of other fossils through protein analysis:

Previous research identified Neanderthal remains using both proteins and DNA — but the success of the latest study could lead to a greater emphasis on getting ancient proteins out of fossils that haven’t yielded DNA, says Chris Stringer, a palaeoanthropologist at the Natural History Museum in London. The method could prove particularly useful for older samples or those from southeast Asia and other warm climates, where DNA degrades quickest.

Neandertal/Denisovan Hybrid?

As J. Lawrence Angel once said: “When two groups of people meet, they may fight, but they will always mate.”  A story is now coming out of Russia describing more research at the Denisova Cave, in the Altai Mountain region that recounts exactly what Angel was talking about.  From Richard Coniff, at Scientific American:

In a remarkable twist in the story line of early human evolution, scientists have announced the discovery of “Denisova 11”—a female who was at least 13 years old, lived more than 50,000 years ago and was a child of mixed parentage. Her parents were not just of different races, but two different and now-extinct early human types. Their exact taxonomic designations—whether they were separate species or subspecies—is still a matter of scientific debate. But the bottom line for Denisova 11 is that mom was a Neandertal and dad a Denisovan.

This is a remarkable claim, similar to the one that Erik Trinkaus made about the Lagar Velho child discovered in Portugal that is thought to be a Neandertal/modern human offspring. What evidence has been marshalled to support this claim?  In a word: genetics.  The evidence is taken from another bone fragment from the site.  From the abstract:

The father, whose genome bears traces of Neanderthal ancestry, came from a population related to a later Denisovan found in the cave. The mother came from a population more closely related to Neanderthals who lived later in Europe than to an earlier Neanderthal found in Denisova Cave, suggesting that migrations of Neanderthals between eastern and western Eurasia occurred sometime after 120,000 years ago. The finding of a first-generation Neanderthal–Denisovan offspring among the small number of archaic specimens sequenced to date suggests that mixing between Late Pleistocene hominin groups was common when they met.

So, if they interbred regularly (or regularly enough, anyway), why aren't they just one species?  Svante Paabo argues that it is because they simply did not come together very often.  To this, I would argue that they probably also had fairly distinct cultures. 

If this kind of information had come out a few decades back, there would have been quite a few squawks and naysayers but as the evidence piles up for hybridization between many different groups throughout the Pleistocene, researchers have become more accepting of it.  It is pretty clear that the evolutionary picture was a whole lot more complex than we thought. 

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