Why Are There Only Two Sexes?

In a world focused on self-fulfillment and self-gratification, it is important to remember that self-denial and self-sacrifice are central to any relationship that lasts.

The glory and diversity of the created world has recently come under a unique form of scrutiny from one group of scientists. Geneticists, seeking to unlock the chromosomal, indeed molecular, secret of species, have now begun to ask a startling question. Why, they wonder, do human beings and higher organisms come in two sexes - rather than, say, three, or five, or eleven, or none?

Why do we come in two sexes' Many species have only one sex. One extravagant species has been shown to have thirteen sexes - the slime molds. Other species of plants and animals have no sexes - like the dandelion, which produces wind-blown seeds entirely without benefit of pollen or any of the complex cellular machinery of sexual reproduction.

From a purely biological standpoint, having two sexes is an odd arrangement. Biologically speaking, it would seem that the more the better - sexes, that is. With only two sexes, 50% of the population are potential partners, but with 20 sexes, for example, 95% of the...