Maybe we’ve found Neanderthals, and they are us.

The intermixing of modern humans and Neanderthals is back in the news: BBC News – DNA yields secrets of human pioneer.

DNA analysis of a 45,000-year-old human has helped scientists pinpoint when our ancestors interbred with Neanderthals.

The genome sequence from a thigh bone found in Siberia shows the first episode of mixing occurred between 50,000 and 60,000 years ago.

The male hunter is one of the earliest modern humans discovered in Eurasia.

The study in Nature journal also supports the finding that our species emerged from Africa some 60,000 years ago, before spreading around the world.

A year ago, I was pretty convinced that we, modern humans, were pretty much responsible for the extinction of the Neanderthals.  Various theories about climate change causing it didn’t seem compelling, since the Neanderthals had been around for hundreds of thousands of years, no doubt weathering many climate variations, but had disappeared right around the time modern humans encroached on their territory.

But the findings in recent years that all non-ethnic Africans have 2-4% Neanderthal DNA, has raised another interesting possibility.  (I wish I could find the article of the anthropologist who speculated about it, but I can’t, so you’ll have to read my amateur snippet.)

It appears that the population of Neanderthals was always low, a few tens of thousands across all of what is now Europe.  When modern humans started encroaching on them, those modern populations were orders of magnitude larger.  Maybe we didn’t eradicate Neanderthals or out compete them for resources (at least not completely).

Maybe we intermarried with and assimilated them.  It might be that Neanderthals didn’t so much go extinct as meld into the population of modern humans.  As someone who is 3% DNA (at least according to 23andMe), I find this idea intriguing.

Given the long history of us regarding the Neanderthals as some kind of ape-like sub-human, there may be resistance to this idea.  But the more I read and think about it, the more it seems like that’s where the evidence is pointing.

Maybe we’ve found Neanderthals and they are us.

Extinct human cousin gave Tibetans advantage at high elevation

It looks like ancient humans got around.  It’s pretty well known now that most of us have Neanderthal DNA, but apparently a lot us also have Denisovan DNA: Extinct human cousin gave Tibetans advantage at high elevation — ScienceDaily.

Tibetans were able to adapt to high altitudes thanks to a gene picked up when their ancestors mated with a species of human they helped push to extinction, according to a new report by University of California, Berkeley, scientists.

An unusual variant of a gene involved in regulating the body’s production of hemoglobin — the molecule that carries oxygen in the blood — became widespread in Tibetans after they moved onto the high-altitude plateau several thousand years ago. This variant allowed them to survive despite low oxygen levels at elevations of 15,000 feet or more, whereas most people develop thick blood at high altitudes, leading to cardiovascular problems.

“We have very clear evidence that this version of the gene came from Denisovans,” a mysterious human relative that went extinct 40,000-50,000 years ago, around the same time as the more well-known Neanderthals, under pressure from modern humans, said principal author Rasmus Nielsen, UC Berkeley professor of integrative biology. “This shows very clearly and directly that humans evolved and adapted to new environments by getting their genes from another species.”

From I recall reading, Denisovans aren’t thought to have been that different from Neanderthals, so this probably isn’t as profound as it initially sounds.  Still, it’s a fairly significant discovery.

For decades, there was a debate between two camps in paleo-anthropology, the out-of-Africa camp, and the multi-regional camp.  The out-of-Africa people believed that modern humans evolved in Africa and subsequently migrated around the world.  The multi-regional camp believed that modern humans in each region evolved from archaic humans in that region, with lots of gene flow between the regions keeping us one species.

The weight of scientific evidence is now firmly on the out-of-Africa side, with genetic studies now allowing scientists to track prehistoric human migrations.  But like many things in science, it’s not a complete victory, since it looks like humans in each region did receive a small amount of gene flow from local archaic humans, and this contribution appears to have provided benefits, such as in the case of Tibetans, a gene for tolerating high altitude conditions.

When It Comes to Neanderthals, Humans May Be the Borg

The extinction and competition hypotheses for the demise of the Neanderthals, notably suggested by interdisciplinary scientist and author Jared Diamond, hinge on the idea that humans were more advanced than Neanderthals. Commonly claimed are the following: that humans had more communicative abilities, were more efficient hunters, had superior weaponry, ate a broader diet, and had more extensive social networks.

But the archaeological record doesn’t back any of those claims, the authors found.

In 2010, scientists discovered that between one and four percent of the DNA of modern humans living outside of Africa is derived from Neanderthals, providing clear evidence that the two species were interbreeding to some extent tens of thousands of years ago. In January of this year, Benjamin Vernot and Joshua Akey of the University of Washington published a paper in Science that corroborated those results. They found that a fifth of Neanderthals’ genetic code lives on within our species as a whole.

via RealClearScience – When It Comes to Neanderthals, Humans May Be the Borg.

As someone who discovered last year that they were 3% Neanderthal, and given the now very low population estimates for Neanderthals, this strikes me as completely plausible.  Maybe Neanderthals didn’t die out so much as marry into the family.  In other words, we are Neanderthals.  (At least those of us who aren’t from recent African stock are.)