Climate's Role in Human Evolution
Millions of years ago, climate change shaped the evolution of the human species. Paleoanthropologist Rick Potts tells Robert Siegel that humans evolved as a response to an unstable environment. Potts is the director of the Human Origins Program at the Smithsonian Institution's National Museum of Natural History.
ROBERT SIEGEL, Host:
This is ALL THINGS CONSIDERED from NPR News. I'm Robert Siegel.
MELISSA BLOCK, Host:
And I'm Melissa Block.
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BLOCK: This week, NPR and National Geographic are launching Climate Connections, a yearlong exploration of how people are changing climate and how the climate changes people. Each month, we'll take you to a different part of the world to hear about different approaches to this global problem, and we'll consider how matters far away can affect life here in the United States. We'll also explore the connections between earth's past and present. In a few minutes, we'll learn how a stable climate shaped the lives of people in Great Britain 10,000 years ago.
SIEGEL: But we'll start hundreds of thousands of years before that with Rick Potts who studies the beginning of human history.
RICK POTTS: We keep the fossil casts of early humans. We also have the only Neanderthal in America...
SIEGEL: Really?
POTTS: ...in my lab, yeah.
SIEGEL: I bet you get some arguments on that, huh?
POTTS: Yeah. That's right.
SIEGEL: Potts is a paleoanthropologist and director of the Human Origins Program at the National Museum of Natural History here in Washington, D.C. He theorizes that what distinguished early humans from their closest cousins was their ability to adapt to volatile climate change.
POTTS: If you see the record of earth's climate going back six million years, you see that right around the time when direct human ancestors were emerging, around six million years ago, there was an increased in the range of environmental fluctuation.
SIEGEL: Rick Potts showed me casts of some old skulls on the table in his office: One, of a Neanderthal, the other of an early Homo sapiens. The two species co-existed for thousands of years. The Neanderthals could fashion crude hand axes from stones; they buried their dead. But as a species, they were incapable of some basic survival skill that Homo sapiens possessed.
POTTS: The Neanderthals were spread out over Europe and the Near East. They pretty much occupied the Near East during cool conditions. And in Europe, of course, they had to adapt to the changing conditions of Ice Age and warmth.
SIEGEL: Over thousands of years?
POTTS: Yeah. They lived for about 200,000 years. They were pretty successful. By comparison, our own species has been around for about 200,000 years. So the Neanderthals were around for about as long as our own species has been around.
SIEGEL: Well, what do we have going for us that this guy, this Neanderthal, whose skull that represents, didn't have going for him? We can say he didn't adapt adequately to the climate but - for lack of I.Q.? What was it that he didn't have?
POTTS: Well, it's - it was a way of interacting with his surroundings that I think was the most important. If you look at the stone tools that Neanderthals made.
SIEGEL: Oh, we have a box of them here.
POTTS: A box of them right here. For example, this kind of little point looks like a miniature hand axe is something that Neanderthals made and they made them consistently for about 200,000 years. They weren't really innovators in technology.
SIEGEL: It didn't quite get past this rather crude design.
POTTS: Now what's the comparison? What's interesting is that the modern humans were bringing things from 450 miles away, and they were able to exchange stone with neighboring groups. They seemed to have all the things in place that even human beings today use to buffer disaster. So when a disaster occurs, there's an ability to look to other groups outside of your immediate social surroundings to try to help you get through. We think the Neanderthals may not have had that whereas modern humans did.
SIEGEL: According to Rick Potts, what saved our ancestors wasn't just one thing, a big brain, or long limbs or the ability to make tools to prepare, and later produce food. It was a general capacity, faced with a threat of extinction, to change.
POTTS: In some ways, you can think of ourselves and the course of human evolution as a matter of species emerging that were specialists in being able to change, specialists in being able to be versatile. And so that explains why we have an emerging history in through deep time of starting out as tropical African adapted to now, a species that has spread all over the world and incredibly adaptable.
SIEGEL: That's Rick Potts of the National Museum of Natural History here in Washington, D.C.
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