This episode looks at how females force males to prove their worth before being accepted as mates.

This episode reveals the sexual strategies that are used to ensure that the sperm reaches the egg.

This episode looks at the strategies the sexes use to ensure they're not the ones left holding the baby.

This episode looks at sex & the role it plays within family groups & the violence & jealousy it causes.

Examines the reasons for sex,how some species have abolished it whilst for others it ensures survival.

This episode focuses on the varied tactics that males use to win females & the chance to mate.