Gorillas, chimpanzees, bonobos and orang-utans - the closest living relatives of humanity - could vanish from the wild within 50 years, say United Nations leaders meeting in Paris. They have appealed for $25m to save the world's great apes from extinction. The western chimpanzee has vanished from Benin, Gambia and Togo. Fewer than 400 remain in Senegal and 300 to 500 in Ghana. The population of chimps in Guinea-Bissau is below 200. Only about 600 mountain gorillas survive in Uganda, Rwanda and the Democratic Republic of Congo.