Scientists discover 'laughter' in apes

Humans are not the only animals that know how to laugh, according to new research.

Scientists at the University of Portsmouth have found that orang-utans display gaping mouths to each other in order to express empathy.

A team led by Dr Marina Davila Ross recorded the primates playing in four centres around the world.

The researchers noted that when one orang-utan "laughed" by opening its mouth, its playmate followed suit less than half a second later.

Dr Davila Ross said: "By mimicking emotional expressions of others, individuals are able to experience and understand the emotions of their social partners.

"Such mechanism of empathy is likely to help us to form and maintain social bonds."

She added: "Until our discovery there had been no evidence that animals had similar responses.

"What is clear now is the building blocks of positive emotional contagion and empathy that refer to rapid involuntary facial mimicry in humans evolved prior to humankind."

© Independent Television News Limited 2008. All rights reserved.