Chimpanzees are humanity's closest living relatives. We shared a common ancestor perhaps as recently as five million years ago, and we share 96 per cent of our DNA. The similarities between the species are so great that some scientists have suggested that they belong together in the genus Homo.

As our nearest living cousin, Pan troglodytes has long been considered among the animal kingdom's leading candidates for a sophisticated intellect. Yet the extent to which chimp intelligence has been found to approach that of people has surprised even some primatologists, as has their ability to perform all sorts of skills once thought to be exclusively human.

In January a chimp named Ayumu performed so well on a memory test that he beat a human, while scientists at the University of St Andrews have shown that chimps better four-year-olds at tasks that involve extracting a reward from a closed box.

True language is still thought to be confined to humans, but some chimpanzees have shown the ability to learn a suprisingly large vocabulary. The best-known case was that of Nim Chimpsky — named after the linguist Noam Chomsky — who was taught to understand 125 signs.

A chimpanzee named Washoe, who died in 2007, learnt to recognise and even to use more than 200 terms in American Sign Language, though the extent to which this comprised a genuine linguistic ability is disputed.

The evidence for chimpanzee tool use - another quality once thought to belong to humans alone — is less ambigious. Chimpanzees have long been observed using twigs to extract termites from mounds and sticks to dig up tubers and roots. In 2007 chimpanzees in Senegal were found to sharpen sticks to use as spears for hunting bushbabies, and there is evidence that ancient chimps at Noulo in the Ivory Coast used stone tools to crack nuts 4,300 years ago.

There are strong indications that this tool use is not always instinctive, but comprises a form of culture that can be taught from one generation to the next. Some scientists believe that chimps show signs of empathy and even morality, though this is more controversial. The animals have complex social structures, and Jane Goodall, the primatologist, has reported chimps in mourning.

Times Recommends

• Postmen: We bind the nation together
• Tewkesbury: when the memories flood back
• Cast Offs actress: I’m happy that my face fits