2010 was a good year for Neanderthals. They've been extinct for thousands of years, but scientists now say their genes live on in us. There were other discoveries as well, all made possible by DNA. NPR's Christopher Joyce reports DNA is becoming a window into the past.

CHRISTOPHER JOYCE: Let's start with the Neanderthals. They were the closest cousins on our family tree until they died out about 30,000 years ago. But were they kissing cousins? Did they exchange genes with us? Scientists wondered. So did NPR science correspondent, Joe Palca, who got straight to the heart of the matter with Harvard geneticist David Reich.

JOE PALCA: We're not talking about exchanging genes as in exchanging trading cards. We're talking about having sex together.

Dr. DAVID REICH (Geneticist, Harvard): That's right, that's right.

PALCA: Glad we cleared that up.

JOYCE: Reich knows it happened because this year he and a team of scientists actually decoded the billions of DNA segments extracted from Neanderthal bones. It was the culmination of years of research into retrieving ancient DNA intact. And what they found was as worthy of a supermarket tabloid as a scientific journal. The Neanderthal genetic code was closer to Europeans and Asians than Africans. If we and they had never mated, their genes should've been equally different from all humans. So what's that mean for us? Reich explains.

Dr. REICH: We estimate about one to four percent of the genetic ancestry of non-Africans is from Neanderthals.

JOYCE: Apparently, though, having some Neanderthal in us isn't a handicap. And the DNA revealed, not just similarities, but also genetic differences between Neanderthals and us - especially things that may explain how we adapted and survived better than they did. Here's Ed Green from the University of California at Santa Cruz talking on NPR's Science Friday program.

Professor ED GREEN (University of California, Santa Cruz): We're using these data now to find some important episode of adaptation in our human ancestors, not that long ago, even since we split from Neanderthals.

JOYCE: DNA technology has given scientists a telephoto lens to look even further into the past. Take, for example, the 40,000-year-old pinky finger found in a Siberian cave. No one could make heads or tails of it until this year, when geneticists at the Max Planck Institute in Germany parsed out some of its DNA.

Its owner was not a modern human, nor a Neanderthal. It did, however, share a common ancestor with us, probably in Africa, and its DNA shows marked similarities with modern people from Melanesia. David Reich at Harvard was on the team.

Dr. REICH: This was a third population living at the same times. And we don't know what tools they made. What we now know is we begin to know them from their DNA.

JOYCE: And if you can find DNA that's more recent, it can tell you even more. For example, scientists this year got DNA in hair from the remains of a 4,000-year-old hunter found in Greenland. At the University of Copenhagen, Eske Willerslev teased out remarkable details.

Professor ESKE WILLERSLEV (University of Copenhagen): We can show that he was genetically adapted to cold temperatures. We can also show, with a very high probability, he had a tendency to baldness, he had this blood type, you know, he had this skin color, etcetera.

JOYCE: Type A-positive blood, to be exact. Thick hair, brown eyes, and of the two types of earwax that humans inherit, he had the dry kind.

Scientists called the hunter Inuk. Willerslev says he's now going to use the same technique on some 8,000 year old mummies from South America.

Prof. WILLERSLEV: That's where I think ancient DNA becomes very powerful, because it gives you a direct look into the past.

JOYCE: There are some limits on what ancient DNA can tell you. Heat, microbes and water destroy it. So the raw material: bones, teeth and hair are best preserved in very cold climates.

But geneticist Terry Brown, of the University of Manchester in England, says that still leaves a lot of fossilized territory to explore. He says the more DNA scientists get the more complex the human story will become.

Professor TERRY BROWN (Geneticist, University of Manchester): I suspect that there are going to be more surprises around the corner. If there are other bones which we can get DNA from, then I think it's possible we may find a greater variation amongst our earlier ancestors than we had previously realized.

JOYCE: And perhaps more clues to those things that gave us the human edge.

Christopher Joyce, NPR News.

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