Monday Musing: Why There Are So Many Men

Confusion reigns in many popular discussions of evolution, and 3QD is not immune. I was inspired to write this Monday Musing today at least in part by a comment left by Ghostman on a post about autism a few days ago. In it, among other things, he theorizes that:

...autism, far from a brain disorder or malfunction, is an evolutionary reaction to the electrified, computerized world, and that once our brains iron out the wrinkles, we will come to look at modern autism as the first difficult steps toward a biological advancement of the human brain—an evolutionary improvement in the way we think, compute, and, yes, imagine...

...I believe the electrified, computerized world is actually changing the makeup of our brains. And that autism is one of the effects of this change...

...Consider the two most well-known symptoms of autism: lack of social skills (encompassing language, empathy, etc.) and enhanced recognition of and appreciation for patterns (often including improved memory and mathematical ability). These, I thought, do not seem to be the characteristics of a human; they are the characteristics of a computer. Computers are bad at emotions, language, social situations. Computers are good at math, memory, patterns. Furthermore, as one reads the literature, one is struck by how many teachers, parents, therapists, etc., comment on how compatible their autistic students, children, patients are with computers. Half of them seem outright amazed. But if one thinks that autism comes largely from computers, one would not be amazed by this, one would expect it...

—Ghostman, June 5, 2007

It's late at night. It is too hard for me to attempt a sympathetic interpretation of this, and in the space that I have, I really cannot even seriously address the various confusions about evolution that are displayed here. (Even if brains were changed by "electricity" or "computers," whatever that means, you should know, Ghostman, that ONLY changes to the DNA of the nuclei of sperm or egg cells can possibly be passed on to one's offspring—and that is just one of the many misunderstandings of evolution that you betray.) Ghostman, I have no doubt that you are well-intentioned, but, my friend, you've got to learn something real about evolution before popping off, okay? Instead, all I can do is make my column today all about how Ghostman and others can most quickly educate themselves about evolution and its surrounding theory.

Unlike, say, quantum theory, the theory of evolution is something a lot of people think they understand pretty well. After all, no advanced math is required to understand the silly and tautological phrase which for some represents all there is to know about evolution: "survival of the fittest." (Who are the fittest? Why, those that survive, of course!) Evolution is an elaborate and broad and subtle theory, with which one needs to spend some years to even begin to get a sense of its richness. (And parts of it do happen to be best expressed mathematically.) Luckily for non-biologists like me (and Ghostman) there exists a beacon of hope in the form of a book: thirty-one years ago, Richard Dawkins wrote what in my mind must be the best presentation of the complexly intertwined ideas and concepts that constitute the theory of evolution, since Darwin wrote The Origin of Species itself. I am referring, of course, to Dawkins's magisterial work, The Selfish Gene. My column today can be seen as essentially an exhortation, a request, even an abject plea: if you haven't read this book, please click here now, buy it, and read it from cover to cover as soon as possible. (Get the 30th-anniversary edition, which restores Robert Trivers's introduction to the original, which had been deleted from subsequent editions, and which also contains a brand new preface by Dawkins detailing the book's history, in addition to the then-new preface by Dawkins for the 1989 second-edition, and, of course, the original preface. The bibliography has also been updated.) If you haven't read it but think that you already know what it is about, you just aren't getting my message. Even Dawkins's foes (such as H. Allen Orr, who recently trashed Dawkins's recent book, The God Delusion, in the New York Review of Books) usually admit that The Selfish Gene is one of the most beautiful and clear expositions of science ever written. And it is not about some one thing or idea that can be easily summarized Cliff Notes-style. You just gotta' read it. Even in an earlier Monday Musing in which I mostly criticized Dawkins for unnecessarily implicitly defending a certain philosophical theory of truth in some of his writings, I also had this to say:

Richard Dawkins has been an intellectual hero of mine since college, where I first read The Selfish Gene. Though I thought I understood the theory of evolution before I read that book, reading it was such a revelation (not to mention sheer enjoyment) that afterward I marveled at the poverty of my own previous understanding. In that (his first) book, Dawkins's main and brilliant innovation is to look at various biological phenomena from the perspective of a gene, rather than that of the individual who possesses that gene, or the species to which that individual belongs, or some other entity. This seemingly simple perspectival shift turns out to have extraordinary explanatory power, and actually solves many biological puzzles. The delightful pleasure of the book lies in Dawkins's bringing together his confident command of evolutionary theory with concrete examples drawn from his astoundingly wide knowledge of zoology. Who doesn't enjoy being told stories about animals?

What I'd like to do in the rest of this column today (in my admittedly ever-desperate hope that it may actually convince someone who hasn't, to read the book) is give a small example of just how brilliantly Dawkins explains questions in evolutionary biology and then answers them in a profoundly satisfying manner in The Selfish Gene. I have chosen this particular topic out of the extravagance of interesting biological issues that Dawkins presents in his book precisely because I had never even thought to formulate the problem, much less guess its elegant and (I think, I hope!) easily-grasped solution before reading him, and because I think I can present it reasonably briefly (we'll see!) . So without further delay, here's the problem: Why are there so many men?

I'll explain. Women, because they must carry a child for 40 weeks, can only have a rather limited number of children in their lifetimes. Of course, there are limits to the number of children that men can have too, but they are much higher in terms of the actual numbers. (I used to be a big reader of the Guiness Book of World Records, and vaguely recall reading at some point that some king or other of Morocco holds the confirmed record for men with more than 700 children! Look it up if you like, but you get the idea of the difference.) Now, those who believe that evolution works for the benefit of groups of individuals, such as species (they are called group-selectionists, and the late, great essayist Steven Jay Gould was one, but he turns out to have been wrong in this, as in quite a few other things—punctuated equilibrium, anyone?), must answer the following question: in a population of humans, fewer than 10% males in a population would suffice to succesfully mate with all the females, so why are 50% (roughly speaking) of humans males? Well, maybe women need men around in some marriage-like situation to take care of their children, otherwise not enough of their children would survive. This is plausible, after all. But then, why is the proportion of men to women almost exactly 50/50? How come it's not 45/55, or 55/45 for that matter, depending on exactly how much the males are needed? Look at some other animal species: we find that cats have the same almost exact 50/50 ratio of males to females. So do dogs, cows, mice, fish, chimpanzees, birds, and walruses. Some species of animals share parenting duties equally between the male and the female, while in others, the female puts in almost all the effort in raising children, but all the ones I have mentioned have the same 50/50 ratio of sexes. Why?

(I am not even mentioning the fact that even before the conception of a child, the female has already put in much more effort in producing it than the male has: consider a species of bird in which the male and female spend equal amounts of time hatching the egg after it is laid, and then also spend equal amounts of time and effort feeding and caring for the hatchlings into adulthood: the female has already made a much greater investment by laying a relatively huge egg—imagine the effort a female chicken expends finding and eating enough food to lay one of the super-nutritious eggs in your refrigerator. Sperm, meanwhile, are a dime a dozen-million! This greater investment of energy on the part of females is the reason, by the way, that human females produce one fertilizable egg a month, and I produce several hundred million sperm a day.)

Let me tell you something about walruses: most walrus males will die virgins. (But almost all females will mate.) Only a few dominant walrus males monopolize most of the females (in mating terms). So what's the point of having all those extra males around, then? They take up food and resources, but in the only thing that matters to evolution, they are useless, because they do not reproduce. From a species point-of-view, it would be better if only a small proportion of walruses were males, and the rest were females. In the sense that such a species of walrus would make much more efficient use of its resources and would, according to the logic of group-selectionists, soon wipe out the actual existing species of walrus with the inefficient 50/50 ratio of males to females. So why don't they?

Here's why: because a population of walruses (substitute any of the other animals I have mentioned, including humans, for the walruses in this example) with, say, 10% males and 90% females (or any other non-50/50 ratio), would not be stable. Why not? Remember that each male is producing almost ten times as many children as any female (by successfully mating with, on average, close to ten females). Imagine such a population. If you were a male in this kind of population, it would be to your evolutionary advantage to produce more sons than daughters because each son could be expected to produce roughly ten times as many offspring as any of your daughters. Got it? Reread the last few sentences and convince yourself that what I am saying is true. Look, suppose that the average male walrus fathers 100 children, and the average female walrus mothers 10 baby walruses. Okay? Here's the crux of the matter: suppose a mutation arose in one of the male walruses (as it well might over a large number of generations) that made it such that this particular male walrus had more Y (male-producing) sperm than X (female-producing) sperm. In other words, the walrus produced sperm that would result in more male offspring than female ones, this gene would spread like wildfire through the described population. Within a few generations, more and more male walruses would have the gene that makes them have more male offspring than female ones, and soon you would get to the 50/50 ratio that we see in the real world. The same argument applies for females: any mutation in a female that caused her to produce more male offspring (though sex is determined by the sperm, not the egg, there are other mechanisms the female might employ to affect the sex ratio) than female ones, would spread quickly in this population, changing the ratio from 10/90 closer to 50/50. Do you see?

No? Well, that's why I keep urging you to read Dawkins's book. He is a much better writer, and a much better brain, honestly, than I am, and even if I can't, I really think that he stands a good chance of winning you over. Get the book. Now!

Here's a bonus video for your having read this post to the end:

All my previous Monday Musings can be seen here.