Neanderthal Genes in Modern Humans

Professor Ed Green discusses sequencing of the Neanderthal genome and signs that early humans interbreed with Neanderthals.





My name is Ed Green and I am an Assistant Professor of Biomolecular Engineering at the University of California, Santa Cruz. My research program is around genome sciences. We study all kinds of interesting evolutionary and biological phenomenon by sequencing, assembling, and analyzing genomes.

We sequenced the genome of a Neanderthal (made of draft of this) back in 2010 and, more recently, a big consortium of folks have published a finished quality genome of the Neanderthal. This has been an incredibly useful reagent for understanding human evolutionary history in many ways.

First of all, it lets us know how we were related to them in great genetic detail. Something that was really hard to do by looking at the fossil and lithic record. Just looking at the bones of our ancestors and their ancestors and the tools that they made.

Opinions vary greatly on how much interaction there was between them and us in the past, and now we know that there was at least some interaction that resulted in viable and fertile offspring individuals, because we see the genes of Neanderthals in the genomes of people throughout the world today. People whose ancestry goes back anywhere in Eurasia and even the New World have a few percent of their genes came not from this group of people from Africa that evolved into humans, but instead a group of people that were living at the same time in Eurasia. The Neanderthals, who were known from the fossil record. We got DNA from their bones and we see that that DNA can be found in people today.

The legacy of Neanderthal ancestry is mostly in people of European, Asian, and New World ancestry. The best model that we have now is that when humans evolved into what we know today as humans (anatomically and behaviorally humans). This happened in East Africa. Something around 100,000 years ago. Very quickly that group replaced all the other groups within Africa and soon after migrated – dispersed out of Africa and within a pretty short time replaced all the other archaic groups in the rest of the world.

Early on, this group of new humans, came into the territory of Neanderthals and interbred with them and mixed with them. Then, the descendants of this population spread throughout Asia and Europe. Went to the islands of Southeast Asia, eventually crossed the Bering Land Bridge and came to the New World, and everywhere they went, in Eurasia and the New World, brought with the Neanderthal genes. So that we see this in people today with ancestry in those regions.

My group is taking a lot of the lessons that we have learned from ancient DNA – recovering DNA from extremely old specimens. Extracting the DNA material, sequencing it, and analyzing it. We’re applying some of this now to the field of forensics. It’s an exciting time to be doing this, because the technology for sequencing DNA is getting so fast and so cheap, and there’s a lot of mileage in this. A lot of the computational algorithms that we use for making sense of ancient DNA can be recycled and used in the field of forensics to ask, “What is the information that we have from human remains in a forensic setting that we have basically developed and refined from ancient DNA?”