This episode explores the amazing bonds that animals have with each other and looks at some of the remarkable relationships they can have with humans.

Hugh Fearnley-Whittingstall is in Costa Rica looking at team spirit in capuchin monkeys. Biologist Patrick Aryee finds out how vultures are saving lives. Zoologist Lucy Cooke is in the US, discovering the medicine that may improve a rare pig's relationship problems. And conservationist Giles Clark finds out how a clever matchmaking technique could help save the clouded leopard from extinction.

The programme also meets the people who, as a result of the rhino poaching crisis in Africa, have struck up relationships with one of the world's most endangered species. In South Africa, scientists uncover an unexpected relationship between two very different animals, and in Australia we find out how man's best friend is helping to bring penguins back from the brink. Show less