DNA Sequencing Will Change Everything

While I’m on the subject of fossils I found this story absolutely fascinating. As DNA sequencing has transitioned from theory to actuality to relatively inexpensive, scientists have been able to isolate and sequence Neandertal DNA, comparing it to our own (as I’ve pointed out here before).

With dizzying speed not only have they been able to sequence Neandertal DNA but they’ve been able to sequence the DNA from enough Neandertal individuals from enough different places they’ve been able to begin doing population studies:

Western Europe has long been held to be the “cradle” of Neandertal evolution, and anthropologists have theorized that climactic factors or competition from modern humans were the likely causes when Neandertals started disappearing around 30,000 years ago. But new research suggests that Western European Neandertals were on the verge of extinction long before modern humans showed up.

This perspective comes from a study of ancient DNA carried out by an international research team. Rolf Quam, a Binghamton University anthropologist, was a co-author of the study led by Anders Götherström at Uppsala University and Love Dalén at the Swedish Museum of Natural History, and published in the journal Molecular Biology and Evolution.

“The Neandertals are our closest fossil relatives and abundant evidence of their lifeways and skeletal remains has been found at many sites across Europe and western Asia,” said Quam, assistant professor of anthropology. “Until modern humans arrived on the scene, it was widely thought that Europe had been populated by a relatively stable Neandertal population for hundreds of thousands of years. Our research suggests otherwise and, in light of these new results, this long-held theory now faces scrutiny.”

Apparently, Neandertal remains from more than 50,000 years ago exhibit substantial genetic diversity, diversity comparable to that of H. sapiens sapiens today. However, and this is the amazing part, the genetic diversity in remains from various locations from less than 50,000 years ago is much, much smaller. That suggests the possibility of some sort of population bottleneck that occurred before our species arrived in Europe.

That’s a bit different from the old theories in which modern-type humans replaced the more primitive Neandertals (or, if you’d prefer, more violent and warlike modern-type humans replaced the peaceful Neandertals). The Neadertals may already have declined substantially when modern-type humans arrived in Europe and those humans may have arrived in a depopulated continent.

Admittedly, the number of individuals who’ve been tested is quite small and the remains quite degraded so we may be getting ahead of ourselves. Still, I have little doubt that these are the sorts of questions we’ll be able to analyze with increasing confidence as the technology of DNA sequencing improves.

What sort of bottleneck? I have no idea. Maybe climate change. Or disease. Smoking? The image of a Neandertal with a butt hanging out of one side of his mouth may stay with me.