As one young couple settles down to start a family, learn how biological and evolutionary forces conspire to keep the human race running. Our bodies work in specific, subtle ways for one reason only: making more humans. Travel inside the body to see what happens to both men and women when attraction occurs and when orgasm finally ensures the possibility of replicating ourselves. Learn why humans are one of only 3% of all mammal species that require both a male and a female for care giving. And discover the evolutionary significance behind the fact that humans mate front to front – when all other species prefer front to back.