GINA gestured for the banana. When Erica offered her a stick of celery instead, single mother Gina, 42, impatiently gestured again. When Erica held up the banana, Gina clapped. She’s better behaved than Theodora, a feisty teenager who throws sand when she is misunderstood.
Gina and Theodora are orang-utans, two of six females that have now been found to communicate with gestures in the same way as people do when playing the game charades. Erica Cartmill and Richard Byrne at the University of St Andrews, UK, presented the apes with a tasty and not-so-tasty food item that could only be reached with human help. As in charades, when the orangs’ signals were completely misunderstood, they broadened the range of signals used and avoided the one that had “failed”. When they were partially understood – when they were offered celery instead of a banana, for example – they narrowed down the range of signals used and repeated them (Current Biology, ).
“It’s similar to what you’d see in young children,” says Cartmill, who designed the experiment to study whether the animals could modify their communication when misunderstood. “The charades strategy is a powerful way of selecting effective signals and getting at a specific meaning,” she says.
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