Chimpanzees are our closest living relatives and so their intelligence is easiest to understand and measure. Chimpanzees in the wild use tools, hunt cooperatively, display signs of mourning, romantic love, appreciation of natural beauty and complex play. Chimpanzees lack the vocal apparatus to manage human speech, but in captivity they have been trained to use and understand American Sign Language. There is still some scientific debate over whether chimpanzees actually understand the language or are simply responding to cues, but in one study, a Bonobo chimpanzee called Kanzi was asked a question he had never heard before: “Can you make the dog bite the snake?” Kanzi searched through his toys to find a dog and a snake, placed the snake in the dog’s mouth and closed it shut using his finger and thumb.
Chimpanzees have a sense of humour and their own version of laughter (a sort of panting sound). Chimpanzees are ticklish and use tickling in their play. They also use simple dollies; grooming and cuddling sticks or stones as if they were babies.