This week's programme in the series on Man and Science today.

Experts estimate that within 30 years - some say sooner - the tiger, orangutan and gorilla will have vanished for ever.

For each year of this century one wild animal has been wiped out. Despite game parks and nature reserves, the natural habitat of many of the great, mammals is being destroyed for ever by Poaching, political instability - and man's need for more and more land.

If this slaughter in the wild continues, we must preserve these endangered animals in zoos. But to breed sufficient numbers and establish zoo banks to ensure their survival would mean changing the format of zoos from ' animal exhibitions' to breeding centres.

Can zoos do it? With a worldwide breeding record for gorillas of under two a year in zoos, just what are the chances for such species in captivity? Or is it the last great battle for survival?
(How would you like to be a gorilla's guest?: see page 15)