The Nature of SexAll nature's creatures, the British novelist Graham Swift once wrote, join to express nature's purpose. And that purpose is illustrated in delightful and sometimes dizzying detail in The Nature of Sex.

Birds, bees, and even barnacles and naked mole rats are driven to join forces to reproduce and pass along their genes to the next generation.

From the sea horse that mates in an hypnotic underwater ballet to the rodent who copulates until he literally drops dead, The Nature of Sex spans the globe to illustrate how an astonishing diversity of life forms find their mates and conceive, raise, and protect their offspring.

This Web companion to the four-part series takes a close look at the primal instinct that causes animals to come together in order to pass along their genes to the next generation.

We also examine how timing can be key in the mating process, and how varied sex contracts create not only new life, but diversity, in both animals and humans.

Watch the full documentary now