Facial expressions, such as the open, gaping mouth resembling laughter, were picked up and copied by orang-utans.
Scientists found that orang-utans had a sense of empathy and mimicry which forms an essential part of laughter.
In the mouse, around 20% turned out to be pseudogenes, whereas in chimpanzees, gorillas and orang-utans the level was closer to 30%.
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The orang-utans will move out in January and return in the spring.
There is evidence that other apes, such as gorillas and orang-utans, show cultural differences, as well as creatures such as whales and dolphins.
She added that the findings shed a new light on empathy and its importance for animals which live in groups such as orang-utans.
Rescued orang-utans, of whom more than 300 are in her care centre in the park, could be freed without danger to the wild population.
When one of the orang-utans displayed an open, gaping mouth, its playmate would often display the same expression less than half a second later.
The second phase will see the orang-utans' outside space extended and a new play area built, and the third phase will mean the gorilla house will be renovated and extended.
The idea of rights for whales is certainly a provocative one, and is reminiscent of the Australian philosopher Peter Singer's proposal that human rights be extended to the great apes chimpanzees, bonobos, gorillas and orang-utans.
Dr Marina Davila Ross, from the University of Portsmouth and Professor Elke Zimmermann at the University of Veterinary Medicine in Hanover, Germany, studied the play behaviour of 25 orang-utans aged between two and 12 at four primate centres around the world.
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