I mentioned that I have been reading Steve Jones’s book Y: The Descent of Men. It’s brilliantly written, often very funny, and full of fascinating information, most of which is probably true.
I’m not going to give a detailed critique, but as a general weakness, the book doesn’t present much in the way of systematic theory, compared with e.g. Matt Ridley’s Red Queen or Genome, or the other Ridley’s Mendel’s Demon. A notable example of this weakness is Jones’s treatment of the Y chromosome itself. As everybody knows, the Y chromosome is a degenerate little thing. It is much smaller than other chromosomes, and most of its DNA is useless junk. Jones brilliantly describes the oddities of the chromosome, but he doesn’t say much about why it got the way it is. In so far as he gives an explanation, it is that because the Y chromosome doesn’t recombine, it has no way of getting rid of harmful mutations, so these accumulate. But he doesn’t explain that this is a controversial view (it is tantamount to accepting the Kondrashov theory of sex), nor that there are alternative theories. One theory is that the Y chromosome is the target of attacks by the X chromosome, and as there are three times as many Xs as Ys in the population, Xs have more opportunities to produce successful mutations. On this view, the Y chromosome and its genes have shrunk in order to present a smaller target to attacks from Xs. On another view, the Y itself is the aggressor, always trying to bias the sex ratio towards males, even if this reduces the overall fitness of the individuals who carry it. This is against the interests of all the other genes in the genome, and since these greatly outnumber the Y, they have succeeded in largely shutting it down, except for its limited function of triggering male development. I don’t know which (if any) of all these theories is true, but they ought to be properly discussed.
However, I don’t want to dwell on Jones’s book (which is a must-read). The rest of this post will be devoted to refuting a number of arguments that are floating round in the meme pool to the effect that men (the male of the species) are degenerate, parasitic, or doomed to extinction. (These arguments are not necessarily found in, or endorsed by, Jones’s book, though such phrases as ‘men are wilting away’ (p.241) do give encouragement to this line of thinking.)
So here, in no particular order, are the arguments, followed by my comments:
Females are the ‘default option’ in the development of an embryo: in the absence of the trigger provided by a Y chromosome, it will develop as a female. The female form is therefore more ‘fundamental’.
So what? This just amounts to saying that an embryo develops as a female unless it develops as a male. The details of the process are of interest to embryologists, but there is no reason to think that the female form is more ‘fundamental’. Vertebrates have had distinct male and female forms for at
least 500 million years (taking this as the date for separation from the tunicates), and this is fundamental enough for me.
The (male-determining) Y chromosome is small and degenerate.
As mentioned above, there are theoretical reasons for expecting this in any heterogametic system of sex determination. It is purely accidental that among mammals males are the heterogametic sex. Among birds and butterflies it is the females who have the equivalent of a Y chromosome, and there are many other methods of sex determination in the animal kingdom.
The Y chromosome will eventually disappear altogether.
Maybe it will, maybe it won’t, but if it does, this doesn’t mean the end of males: it just means that some other system of sex determination will have taken over.
The male gamete (sperm) is essentially parasitic, exploiting the larger egg which provides all the nutrition for the embryo.
It’s true that there is a division of labour between the large immobile egg and the small mobile sperm. There are game-theoretical reasons for expecting such specialisation. Both functions (nutrition and mobility) are equally necessary for sexual reproduction. If all gametes were big fat eggs, just sitting around waiting for something to happen, they would never get fertilised. To describe a mutually beneficial division of labour as ‘exploitation’ is fallacious. Incidentally, not all sperm are small, and sperm and eggs should strictly be defined according to whether or not they are mobile. If sperm are defined as mobile gametes, it is likely that all gametes were originally ‘sperm’.
Most males are a ‘waste’, as reproduction would be more efficient if there were a small number of high-quality males ‘serving’ a large number of females.
Leaving aside the question of parental care, there is some truth in this. The roughly equal sex ratio is a result of selfish genes rather than ‘good of the species’. However, describing males as ‘waste’ implies a value judgement which I don’t necessarily share. In the human species, males have historically contributed a large proportion of creative thought, science, art, etc. Admittedly, if I were a eugenic dictator, I would probably keep most of the women, while culling about 90% of the men – provided I were in the remaining 10%.
Females do most of the hard work of reproduction, providing nutrition and
maternal care, while males just provide a squirt of genes and then run.
Not really fair in the human case, as men (in most societies) provide a great deal of paternal care. In any case, the value of the genes themselves should not be underrated. It is arguable that in most species sexual selection for males helps maintain and improve the quality of genes.
With the prospect of cloning, etc, males are unnecessary and could become
redundant. Women will be able to clone themselves or recombine genes with their lesbian lovers.
The technical obstacles to human cloning are still formidable, but let’s assume they are overcome. What is possible for women will also be possible for men. Admittedly men might need to borrow a denucleated egg and/or a womb, but a pig’s would probably do. And if we are assuming unlimited technical advance, then men could probably grow their own eggs, as they have all the genetic information they need for the purpose. But the conventional method of reproduction is a lot simpler, as well as more fun. Whatever method of reproduction is used, it is likely that something equivalent to sex will still be needed. There is much debate about the reasons why sexual reproduction is so prevalent (Williams, Hamilton, Kondrashov, etc.) , but it must clearly have some major advantage(s) to offset the ‘two-fold cost’ (Maynard Smith). As for lesbian lovers combining genes, I am all in favour of girl-on-girl action, and I would like to suggest Christy Turlington and Cameron Diaz as the pioneer ‘combiners’. Go girls!
DAVID BURBRIDGE
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