AILSA CHANG, HOST:
So when did our human ancestors start making tools? Well, the earliest artifacts that we know of date back more than 3 million years, but early finds had been scattered and inconsistent until new findings from modern-day Kenya. Researchers had studied a site there for 15 years and uncovered more than a thousand artifacts - tools made and used by early humans continuously for 300,000 years. David Braun is the lead author of this new study recently published in the journal Nature Communications. He's a professor of anthropology at George Washington University. Welcome.
DAVID BRAUN: Thank you.
CHANG: So just describe these tools for us 'cause we're not talking about, like, axes or arrows or anything like that, right?
BRAUN: No. These are relatively simple tools. It's basically a rock that has been hit, probably by another rock, to make small chips of stone. But they have sharp edges on them, and those sharp edges provide the ability for early humans to cut things in ways that they can't do with either their teeth or anything else. And that is a kind of - a pretty dramatic change in terms of their ability to access some resources.
CHANG: So cool. So these are, like, the earliest known knives, if you will?
BRAUN: Yeah, that's a pretty good way of describing them.
CHANG: And why is it a big deal that early humans were building basically the same tool over hundreds of thousands of years?
BRAUN: The fact that we see a very similar technology for such a long period of time suggests that early humans are at least, like, learning from each other about how to make these over an extended period of time. And that doesn't necessarily mean that they were teaching each other, which is kind of a very human thing to do.
CHANG: Yeah. These weren't, like, apprenticeships happening, right (laughter)?
BRAUN: Exactly. Yeah, yeah. No, there's not - we can't know whether or not they're doing that kind of thing. But the fact is, that they're actually learning from each other is kind of important because what we as humans do really well is we transfer information between each other.
CHANG: Yeah.
BRAUN: And so this is one of the first times we can really see that maybe they're doing that at a pretty high level over a very long period of time.
CHANG: So how does that change the way we think about our ancestors?
BRAUN: What we can say from our findings is that early humans consistently used this technology over this relatively long period of time in the past, which suggests it's not just sort of a one-off kind of invention and then it disappears, which is what we kind of thought was going on with the early record - was that maybe early humans just invented it and then didn't do it for a long period of time. So that kind of changes the way we think about it a bit.
CHANG: Well, let's talk a little bit about this project because it took over a decade and you excavated these finds in modern-day Kenya. They were analyzed in the Netherlands. Did you expect this work to take that many years?
BRAUN: No.
CHANG: (Laughter).
BRAUN: Not at all. We did the initial survey in about 2012, but, you know, this is in a very remote part of the world, right?
CHANG: Right.
BRAUN: It takes us three, four days just to get up to where our camp is, and so it does take a long time to actually accumulate the evidence. In this instance, what the difficulty was is that we kept excavating new places we thought they were the same age, but it would take, you know, six months for the samples to get to the Netherlands to be analyzed. When we finally got the results, we realized, actually, those are not the same age. And so over several years we had to kind of hit and miss as to what we were actually finding until we could determine that there was actually quite a sequence of different sites - things that we initially thought were about all the same age.
CHANG: That's so fascinating, how painstaking it can be....
BRAUN: Yeah.
CHANG: ...To confirm...
BRAUN: Yeah.
CHANG: ...These kinds of findings. Well, what remaining questions do you have about these particular finds now that the paper is out?
BRAUN: I think one of the surprising things that we identified was that it is a very simple technology, however, to be able to make these things consistently, you really need to understand something about stones, about different types of rocks because they selected very specific rocks to do this.
CHANG: Oh, wow.
BRAUN: So that would suggest that this is maybe not their first rodeo, right?
CHANG: (Laughter).
BRAUN: Once we realized just how old these were, we started thinking, well, we should probably be looking even older in the archaeological record.
CHANG: David Braun is a professor of anthropology at George Washington University. Thank you very much. This was so interesting.
BRAUN: Thank you.
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