Talking With Apes

A bonobo, one of the types of apes whose gestures humans can intuitively understand. (Source: San Diego Zoo)

Odds are you do most of your talking with your mouth, but humans communicate on many different levels. Every hand gesture or facial expression communicates information, without us necessarily being aware of this process. Pure language is on a different level. It requires some degree of consciousness, an awareness of other entities and a desire to deliberately impart information to them. This is not a behavior limited to Homo sapiens. Dolphins click, elephants rumble, and apes gesture to each other.

A recent study from researchers at the University of St Andrews in Scotland has found humans can instinctively understand many ape hand gestures with a high degree of accuracy. It had been observed before that bonobos and chimpanzees share common gestures, along with some with the more distantly related gorilla and orangutan. However, this is the first time that human understanding has been assessed. The success of this study suggests the knowledge is evolutionary engrained from a common ancestor shared between humans and apes.

A screenshot of the game participants played, which can still be accessed here.

In the course of this research, participants played an online game where they were shown twenty different videos of ape hand gestures. Half of the participants got the video only, while the other received a brief description on the context of the gesture. The latter group was only slightly more successful, suggesting the understanding is inherited biologically. Participants averaged a success about half the time, far higher than expected.

So why then is this behavior largely absent in humans? The simple answer is that as we develop our speech centers, our use of nonverbal gestures falls by the wayside. Interestingly, a separate study found that preverbal human infants evince over fifty gestures that closely align with the ape gesture language. This is all the more evidence that the behavior traces itself to a common human-ape ancestor.

Koko the gorilla, who in the 1970s was a part of a pioneering study into ape sign language. (Source: PBS)

While animal communication is accepted as a fact now, this was not always the case. During the Renaissance, the natural sciences were closely intertwined with theological studies. To speak and communicate was to have a soul, something no animal could have. Now we understand the division between humanity and the rest of the natural world is not so distinct. Humans may be the most talkative animal, but we are far from the only ones communicating with each other.

Now that the link between human and ape gestures has been found, further research will have to be done to find commonalities between the ape language and gestures we produce unconsciously. It could be that our simple hand gestures are tapping into an ancient language we are not even aware of.