This chapter is about the conveyer belt of human life: the process via which human beings make new human beings. The topics covered include choosing a mate, falling in love, fighting off rivals, having kids, and finally helping shepherd those kids safely to adulthood, so they can begin the whole process again. Among the questions tackled are the following: Where do our standards of beauty come from? Are they inventions of culture or does it go deeper than that? Why, when choosing sexual partners, are close relatives almost always off the menu? Is love a recent invention of Western culture – or is the idea that love is a recent invention of Western culture itself a recent invention of Western culture? Why do we fall in love and why doesn’t it always go smoothly? Why are most of us so worried about our sexual partners having other sexual partners? It’s not as if we worry about our friends having other friends. Why are people so much more willing to feed and clothe their own children than the next-door neighbour’s children? And last but not least, why are chimpanzee’s testicles nearly as large as their brains, whereas our brains dwarf our testicles?