AUDIE CORNISH, HOST:
All right, if you're not driving, take a look at your hands. It's probably not something you think about a lot, but they're pretty amazing. Our short fingers and relatively long thumbs can grip things with precision. And this ability is far beyond that of our closest living relatives. The great apes, chimpanzees for example, would find it really hard to hold a pencil like we can. NPR's Nell Greenfieldboyce reports that our unique way of handling objects may actually be older than scientists used to think.
NELL GREENFIELDBOYCE, BYLINE: You, me and everyone you know is an official member of the species Homo sapiens. And the earliest ancestor in our group is a species called Homo habilis, which means handy man. Matthew Skinner is a paleoanthropologist at the University of Kent in the United Kingdom. He says this species has hand bones sort of like ours, and it's long been thought to be the first maker of stone tools.
MATTHEW SKINNER: Stone tool use - and tool use generally - is something that's really been used to differentiate the genus Homo and our group Homo from what came beforehand.
GREENFIELDBOYCE: What came before was an even earlier ancestor, called Australopithecus africanus. Skinner and his colleagues wanted to see how it might have used its hands. The researchers knew that bone responds to the forces and stresses put on it. So they used a powerful scanning technique to peer inside some of these ancient hand bones. They saw something surprising, a distinctive structure that seems to be created by forcefully opposing your thumb with your fingers. Skinner says chimpanzees don't have it. But it is found in stone tool users.
SKINNER: It's clear evidence that these australopiths were using their hands and using grips that are very consistent with what modern humans did and what our recent relatives, like Neanderthals, did.
GREENFIELDBOYCE: Now, the first stone tools date back to around 2.5 million years ago. The bones in this study go back a half-a-million years before that. Brian Richmond is a paleoanthropologist at the American Museum of Natural History in New York. He says there have been other hints that human ancestors were using stone tools much earlier. One group recently found animal bones from 3.5 million years ago that seemed to have telltale cut marks.
BRIAN RICHMOND: But that's been controversial. Not everyone has accepted that.
GREENFIELDBOYCE: He says this new study is really cool, but it's still not proof that this ancestor used stone tools.
RICHMOND: What it is - it's direct evidence of handling objects in a fairly humanlike way.
GREENFIELDBOYCE: What objects they were handling and why is the big mystery. Nell Greenfieldboyce, NPR News.
NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.