Why Are there Only Two Sexes?

Have you ever heard of the New Mexico whiptail? Probably not. The New Mexico whiptail is the only animal species – that I know of – whose members all have the same gender: all New Mexico whiptails are female. There is no need for mating with male New Mexico whiptails in order for these females to lay eggs, which is a good thing since there are no male New Mexico whiptails. But this made me wonder: why are there so few species having only one gender? Why do we human beings, and so many other animals, need two “versions” of our species in order to prevent ourselves from extinction? Why not three or four? Is this number utterly random? Or might there be some reason behind it?

Before thinking about this question, I saw absolutely no reason for there being this dichotomy of “men and women” ruling the animal kingdom. I thought to myself, “Why can’t there be just one “type” of human – which we could then call “human” – that, just like the lizards, gives birth every now and then to a new member of the species – that is, without requiring any “intervention” of the opposite sex? What would be wrong with that? Hmm…maybe it’s inadequate to ask whether it is “right” or “wrong” for there to be men and women. Nature – after all – doesn’t seem to care much about being morally right or wrong. Why else would it give AIDS to babies who are free from having done any harm to this world of ours? It is more likely that – given that there would be an explanation – there is a biological explanation for there being this distinction between men and women.

So let’s see: what could be the purpose of “nature” in making two types of human? How could that ever be beneficial for so many animal species – including our own? Well, the distinction could be nothing more than an extremely evolutionary developed instantiation of Adam Smith‘s idea of division of labor. A division that seemed to be working so well that nature extinguished almost all species not conforming to this division. For this evolutionary explanation to be true, it would have to be the case that men and women together should be able to achieve more than only men or only women could ever do.

Here’s the deal: one could claim that a division of labor – in which the woman carries the baby and the man gathers the food – could be beneficial for both parties with regard to their reproducing potentials. Because think about it: chasing swine while being pregnant does not seem to be very convenient. In this case, having the woman at home – safely warming herself at the fire – and having the man out hunting – not having to worry about endangering the life of his unborn child – could be a division benefiting both parties.

Another biological explanation for the existence of men and women exists could be that the existence of both men and women provides both parties with some sort of “purpose in life”: a purpose to form little groups, called “families”, thereby creating structure into – what otherwise might have been – chaos in the animal kingdom; a structure that would make every creature – men and women – within the animal kingdom better of. Because again, think about it: what would the world look like in case there would only be one type of purposeless creature wandering around? Wouldn’t that lead to an utterly unstructured and – therefore – unsafe environment? If that indeed would be the case, it might have been evolutionary beneficial for our species to “develop” the distinction between men and women; simply in order to “program” the species members with a goal: to create that save little world they can call their family. In other words: maybe it’s just a trick of nature to make it seem like we have got some purpose in life; that we have just got to create a family, take care of it, and then – and only then – can we be happy.

However, both of these explanations don’t explain why there are only two sexes; maybe humanity would be even more organized – and even better off – if there were three, four or even more sexes. So why only two? Well, maybe nature “decided” to go for only two because creating more than two might have complicated things a little bit too much. Now it’s at least clear what everyone has got to do: find a man or a woman, make a family and go for it.

But what do you think?

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>