Success from the Neanderthal Genome Project

Silhouette of a male Neanderthal

When my labmate first showed me this paper, we marveled at the sheer number of authors. By my count, this work is credited to 56 scientists with 21 different affiliations (including UC Berkeley) in 7 countries. I don’t even know how to count the number of PI’s here; clearly it was a huge undertaking.

But now, knowing what they actually accomplished, I’m almost surprised that it took only 56 people. They sequenced over 4 billion base pairs, using three samples of bone from Neanderthals that have been dead for about 40,000 years. Most of the bones used were found in the Vindija cave site in northern Croatia.

The results tell us about the relationship between humans and Neanderthals during the late Pleistocene era: between the time when they split into two separate species (400,000 years ago) and when Neanderthals disappeared (30,000 years ago).  Human subjects with European or East Asian ancestry had significantly more genes in common with the Neanderthals, compared to people from South or West Africa.  This means that about 80,000 years ago, sometime after humans migrated out of Africa, they must have come into close contact with Neanderthals—close enough to interbreed and leave Neanderthal genes in the DNA of non-African modern humans.

[As an aside, I’d like to take a moment to defend Neanderthals from all the flak they get in popular culture. Evidence suggests they had language, tools, and weapons—meaning they were just as advanced as humans at the time, and their extinction could have been largely due to unlucky circumstances. Some people even think that Neanderthal descendents are still alive today, so think twice before you use Neanderthal to mean “buffoon”.]

One crucial step in this type of study: proving that the DNA sequenced was actually from Neanderthals. A major challenge in collecting DNA is avoiding contamination with modern human DNA, because the two genomes are so similar (not to mention the fact that most of the DNA in ancient bone samples is from microbes). Thanks to careful tagging of sequences before the sample ever leaves the clean room, the authors estimate less than 1% contamination (compared to up to 40% in previous studies).

As you can see from the title, this “draft” sequence is only the first result of many expected to come from the Neanderthal Genome Project. Of course this is a controversial subject, so keep an eye out for more information on the love story between Homo sapiens and  Homo neanderthalensis.
