Mom and daughter chimp create a new, private signal to communicate

How cool is this?  Scientists have observed a mother-daughter pair of chimpanzees develop their own private signal for when the daughter wants to travel on mom’s back.  We have seen chimps use commonly accepted gestures to communicate with each other: palms up for “feed me” or a loud, long scratch for “groom me.”  But here is an example of two chimps creating a new gesture, with a meaning they have agreed on, and known only to them.

Wow.

Scientists were observing a group of eastern chimpanzees in Kibale National Park, Uganda, when they noticed that when one juvenile, Lindsay, covered her mother’s eye with her hand, mom would let Lindsay climb on her back for travelling. 

Intrigued, they went back to video recordings made over a five-year period.  They saw that Lindsay began covering her mother Beryl’s eye, perhaps accidentally, at about age 3 ½. Within about a year, however, the videos showed that the hand gesture had taken on meaning: Lindsay did it when she wanted to ride on mom’s back, and Beryl (usually) obliged by letting her climb on. 

The tapes had captured the hand-on-eye gesture between Beryl and Lindsay 21 times. Fifteen of them occurred in initiating joint travel or resuming joint travel.

The scientist then focused their observations on Beryl and Lindsay for seven months. They observed Lindsay make the hand-on-eye gesture 29 times, all of which occurred during 15 instances of joint travel. The gesture either led to initiating joint travel (6 times) or Lindsay made the gesture after Beryl stopped moving (9 times) after which mom resumed moving 5 times. (Hey, even chimp moms get tired sometimes.)

The scientists observed 1,203 mother-child interactions over a five-year period, involving 12 mother-child pairs.  They only observed the same gesture three times among other mother-child pairs, and none of those juveniles did it more than once.  It appears that this gesture—and its meaning—is unique to Lindsay and Beryl. 

Not only can chimpanzees use gestures to communicate their thoughts and desires to each other, but two chimps can make up a new gesture, unique to them, that communicates a meaning only they understand.  Strikingly similar to how two human friends can share a “knowing look” that communicates a message only they know.

We share more than 98% of our DNA with chimpanzees. And the more we watch them, the more we see how much we have in common.  

The study is published in the journal Animal Cognition. The video by the study authors, Bas van Boekholt et al., is reproduced with permission under the Creative Commons license.