So, how do you make a gorilla stew?

YOU keep him waiting for three hours. And if you told that joke in Africa, you'd get more hearty laughs than in Asia. Naturalists have discovered orang-utans and other Asian apes laugh less than their African cousins, such as gorillas and chimps. And they also found that, while humans first learned to laugh from their ape ancestors millions of years ago, we have since learned to use laughter to sneer, mock and ridicule.

'Our observations showed strong differences in the use of laughter between the Asian great apes (orang-utans) and the African great apes (gorillas, chimpanzees and bonobos),' said Dr Marina Davila Ross, of the UK's University of Portsmouth.

'Asian apes and humans laugh clearly more often.'

Evolution has enabled humans to use laughter to mock others while apes simply laugh to enjoy themselves and influence others, she concluded.

'But something happened in the last 5 million years which means humans use laughter for a much wider range of situations.'

Dr Ross, who worked with the University of Veterinary Medicine in Germany, also showed sounds other than laughter can evolve in the context of tickling. Mammals, including flying foxes, make sounds when they are tickled but they are not necessarily laughing.

Metro Ireland, 12 January 2010, p5.