The instinct to have sex is one of the most potent we possess. It’s vital if we are to produce the next generation. In this programme we find out what it is about the way we look, the way we smell and what we possess, that can attract the ideal mate. Salsa dancing is one way to express our deepest desires. The Perfect Date Our instincts drive all of us to have sex - and so potentially to have children. But the way men and women go about this is very different. Two actors were sent on to a London University campus with hidden cameras to ask a simple question: "Will you sleep with me?" One is a woman asking men and the other a man asking women. The results could not be more different. Just as in the original experiment (by Elaine Hatfield of the University of Hawaii and Russ Clark of the University of North Texas) no women said yes but three-quarters of the men thought it sounded a good idea. The difference in men and women’s approach to sex has an evolutionary basis. Each month a woman releases just one egg. Should this egg be fertilised she then has to carry the baby through nine months of pregnancy. It’s a big investment. In contrast a man has virtually limitless sperm available and could father hundreds of children in the same nine months. So it’s not surprising that women tend to be more choosy when deciding just who to have sex with. Men and women both want children, but they have evolved very different approaches to the mating game. A Match Made in Heaven When looking for a partner people instinctively respond to a whole range of signals. The simplest of these is body shape. For women, a narrow waist and wide hips are a sign of fertility and therefore prove highly attractive to men. Women are instinctively drawn to body shapes that signal good genes. So she is more likely to go for a man with wide shoulders and a narrow waist- a sure signal of both physical strength and a good immune system. But we also detec