Human hands haven’t changed much in the last few million years. While the difference between human and ape hands is often cited as an evolutionary success story, allowing humans to use tools, human hands may actually be less evolved than some of our primate relatives’, according to a new study from researchers from George Washington University and Stony Brook University.

The research, published in Nature Communications, examines the human hand in relation to chimps, living apes, and fossils from human ancestors like Ardipithecus ramidus and Australopithecus sediba. Human hands have longer thumbs in relation to the rest of the fingers, while chimpanzees (and most other apes other than gorillas) have longer index fingers.  

Human hands displayed few changes since people and chimps diverged from their last common ancestor around 7 million years ago, suggesting that it’s the chimps’ hands that are actually newer in evolutionary terms. The long fingers and short thumbs of chimps were a later adaptation that allowed them to live in trees. 

If human hands, by contrast, are more primitive, it probably means the changes that allowed humans to begin using a wide variety of tools were not due to differences in hand structure, but to neurological adaptations. 

[h/t: Science News]