The evolution of life on earth determined the existence of two sexes, and since then males and females have combined their genes in order to reproduce. But the females often have to do almost all the work, and in addition are, mistakenly, referred to as the “weaker sex”. Different animals have adopted different strategies in relations between males and females, but the common denominator is that both want to pass on their genes, and have the healthiest possible children. The difference lies in the fact that the males have small, abundant sexual cells, which are produced continuously. The females, on the other hand, possess the valuable, scarce and enormous ovules. All subsequent inequalities stem from this basic difference. The ovule is large because it contains considerable reserves, important substances for the development of the embryo. The sperm, in contrast, arrives empty-handed; it contributes its genes and leaves the rest of the work to the ovule, now transformed into an embryo. This, in principle, means the male can simply disappear after copulating, leaving the female in charge while he goes off in search of more females to inseminate. But it does not always happen that way. Often, the male stays to help bring up his children, and at the top of the evolutionary scale this acquires complex connotations. When the female in question is a woman, things should be different, and yet in the majority of the world they quite simply aren’t. In almost all cultures, women have always been oppressed in one way or another. In male hominids, natural selection favoured the characteristics of a fighter and protector, making them big and strong, while in females the emphasis was on cooperation and child rearing. So, from a biological point of view, the physical supremacy of men is quite correct. But we are also cultural beings, and what 30,000 years ago was extremely useful for survival is today simply an injustice. Human culture, instead of compensating for the biological fact that reproductive responsibilities are largely borne by women, has taken advantage of the greater strength of the male to establish a historic patriarchy. There can be no denying that men and women are different, but not as much as social traditions would have us believe. Discrimination against women is, unfortunately, one of the few features that virtually all the cultures of the world have in common. The possessors of the valuable, scarce ovules end up being lovers, wives, mothers, educators, cooks, gatherers, artisans and, all too often, martyrs. Nonetheless, the biological system was well designed, the family functioned as a social unit and human beings colonised the entire planet. What strategies did other animal species adopt? Among the birds, there are such curious cases as that of the ostrich. When the breeding season arrives, both males and females actively participate in courtship. The male will already have dug a number of shallow holes in the ground, and when he has inseminated the females, they will lay up to 20 eggs in these nests, for him to incubate. One of the females will help him, but the rest can then forget about their children for a while. When the chicks of all the females have been born, the male and the different mothers take turns to protect them. It’s very unusual among birds for females to deliberately take care of the eggs of others, but the system benefits everyone. The fact is, there are many animal species in which the males and females have an almost perfect relationship, sometimes taken to poignant extremes. as, for example, here in Africa. The dic-dic are antelopes the size of a hare, which mate for life. This system is called the “strategy of conjugal fidelity”, and in it the females choose the males, forcing them to perform a long, gruelling courtship until they have given sufficient proof of perseverance and fidelity. In Africa, it is said that when one dies, it won’t be long before its mate follows it. However, the most common mating strategy is very different. Biologists call it the “strategy of the virile male”. In those species that adopt it, such as this Indian rhinoceros, the females are resigned to receiving no help from the father of their children, and instead devote all their energy to finding the best genes. The females only allow a few males to reproduce. They want only the best genes, practising sexual selection and forcing the males to compete against each other. The consequence of this strategy is that, over time, the males become bigger and more powerful, but also more selfish. The “strategy of the virile male” has filled the world with males anxious to copulate, capable of performing the most spectacular demonstrations of strength.