Ape hand gestures reveal where humans evolved language

Until recently, scientists figured that the origins of human language could be found in our vocal cords. That seems reasonable enough, but the latest evidence suggests our hands are actually the source of language...and a bunch of hand-waving primates agree.

The latest theories of language evolution suggest that how we make the sounds of language - which of course primarily happens in our voice boxes - is less important than how we convey meanings. Hand gestures and body language can be just as vital to communication as spoken words, and the burgeoning gesture theory of language evolution suggests that the complex spoken languages we use today actually spring from the relatively simple ideas our ancestors conveyed with their hands.

Researchers at the Max Planck Institute have now offered some serious support for that theory through their research with our four closest evolutionary relatives: chimps, bonobos, gorillas, and orangutans. They found that all four of these species develop a complex system of hand-waivng and gestures in the first twenty months of life. These range from simply poking other apes to get their attention to slightly more abstract gestures like shaking their heads or extending their arms outward.

Crucially, these gestures don't serve any purpose if no other apes are watching, which means the young wouldn't bother doing them if they weren't cognizant of others. These gestures suggest apes know from a very young age that they can convey meaningful ideas to each other. As the researchers point out, the fact that this develops so young separates the great apes from monkeys, who only develop such gestures as adults. We and our ape brethren seem to share an innate capacity for...well, calling these hand gestures "language" might be pushing it, but certainly something along those lines.

University of Auckland researcher Michael Corballis adds:

"In monkeys, intentional arm movements are dedicated mainly to grasping. Communicative gestures probably emerged in apes, and began to assume grammatical forms in hominins."

There are some crucial differences between how humans and the other great apes communicate, of course. Human infants develop the same basic gestures to mean the same basic things no matter where they're raised. This was shown by a recent study, which found that children in several different cultures all pointed their index finger at 14 months, and all for the same basic reasons.

Apes, on the other hand, didn't show any common meanings for their gestures either across or within the various species. The only commonality was that apes used the hand gestures in sophisticated ways from a young age, but the exact gestures and meanings attached to them varied wildly. Perhaps the common ancestor of all the great apes had one set of gestures that meant specific things - it's even possible that this incredibly rudimentary communication forms part of the DNA of modern human languages - but the different ape species diverged in how they used those gestures long ago.

American Journal of Primatology via New Scientist. Image by Rennett Stowe on Flickr.