Desmond Morris looks at the evolutionary reasons for men looking like men and women looking like women.
Learn more about the mating display signals of different cultures.
Is it biologically natural for us to be faithful to one mate all our lives? Are we by nature monogamous or polygamous?
At every stage of life the rituals both join and separate the sexes.
Find out the problems that living in cities have brought to the human species, how cultures have often favoured the birth of boys over girls, and how different cultures cope with looking after a baby.
See how western wedding rituals reflect the subordination of the woman to the man.