"Human beings are the sexiest primates alive," states Desmond Morris and then goes on to justify this controversial remark in The Biology of Love, the fourth part in his personal view of the human species.
Morris explains that we have extended our sexuality in many ways: we are interested in mating at any time regardless of whether conception is possible; our courting and lovemaking is more prolonged than any other species; and the intensity of the female orgasm is unique among primates. In this film, advanced camera techniques are used to illustrate the intense physiological changes that take place during the human sexual act.
As well as going step by step through the ritual of courtship in the programme, Morris also explores the concept of "pair bonding", the reasons for unfaithfulness, the origins of homosexuality and the attitudes of society to all aspects of human sexual behaviour.
"One thing is clear," he concludes, "of all our many behaviour patterns, copulation clearly remains one of our most successful and there are nearly six thousand million human beings alive today to testify to this."