1:50am UK, Tuesday September 06, 2005

Baby chimpanzees express emotion by smiling and pulling faces just like human infants.

A study of 37 chimps in their first months of life at a US research centre has revealed striking similarities with humans.

180 chimpanze pulls face

Chimps show emotions too

All smiled to show happiness within the first three weeks of birth, said Dr Kim Bard from the University of Portsmouth.

Infants tended to smile when they were placed face-to-face with a human examiner. They also uttered vocal greetings.

Like human babies, they imitated carers who opened their mouths and stuck out their tongues.

They were also able to imitate a sequence of sounds within the first weeks of life.

Chimps who were kept in an environment where carers responded to their emotional needs were more communicative.

But they also became angry when the help they came to expect was not forthcoming.

Dr Bard conducted the study at the Yerkes Primate Research Centre at Emory University in Atlanta, Georgia.

He said: "Many of the characteristics that we find engaging in our infants, such as smiling when we smile at them, are also present in chimpanzee infants."