And back in 2010, a team led by paleoanthropologist Sergio Almécija, now at George Washington University in Washington, D.C., began arguing that even earlier human relatives, dating to 6 million years ago-very soon after the human-chimp evolutionary split-already had humanlike hands as well. The earliest humanmade stone tools are thought to date back 3.3 million years, but new evidence has emerged that some of the earliest members of the human line-such as the 4.4-million-year-old Ardipithecus ramidus ('Ardi')-had hands that resembled those of modern humans rather than chimps, even though it did not make tools. For decades the dominant view among researchers was that the common ancestor of chimps and humans had chimplike hands, and that the human hand changed in response to the pressures of natural selection to make us better toolmakers.īut recently some researchers have begun to challenge the idea that the human hand fundamentally changed its proportions after the evolutionary split with chimps. Chimps, on the other hand, have much longer fingers and shorter thumbs, perfect for swinging in trees but much less handy for precision grasping. We have a relatively long thumb and shorter fingers, which allows us to touch our thumbs to any point along our fingers and thus easily grasp objects. Humans and chimps diverged from a common ancestor perhaps about 7 million years ago, and their hands now look very different. The findings have important implications for the origins of human toolmaking, as well as for what the ancestor of both humans and chimps might have looked like. But a new study suggests a radically different conclusion: Some aspects of the human hand are actually anatomically primitive-more so even than that of many other apes, including our evolutionary cousin the chimpanzee. Many scientists have assumed that our hands evolved their distinctive proportions over millions of years of recent evolution. It can thread a needle, coax intricate melodies from the keys of a piano, and create lasting works of art with a pen or a paintbrush.

Caesar the chimpanzee hand