David Attenborough examines how, in the animal kingdom, recognising friends and respecting the power of rivals is vital.

For baboons, it is not how big they are but who they know that counts, whilst chickens need to know their place in the farmyard peck order. But there are unlikely friendships too. Vampire bats not only scratch one another's backs but also share their grisly meals of blood. When millions of sister insects work together, slavishly serving their queen, the resultant superorganism dominates the forest. Show less