Homo Mysterious: Evolutionary Puzzles of Human Nature by David P. Barash Read Free Book Online

benefit derived by a concealed ovulator would be shared by everyone, including those whose reproductive statuswas public. On the other hand, if the payoff of concealing one’s ovulation rests upon keeping the peace, then presumably those who weren’t thus concealed would have gained something by going public—and yet, they would be the only ones to profit as a result, while the costs of chaos would largely extend to everyone. Therefore, although concealing one’s ovulation might have benefited society as a whole, it is difficult to see how it would have been selected for at the level of individuals and their genes, which is pretty much the only way natural selection works. v
Self-Deception and the Headache Hypothesis
     
    There is yet another important hypothesis that remains to be considered. It is especially intriguing for several reasons. For one, it brings in a seemingly independent evolutionary mystery, namely, consciousness. vi For another, it confronts one of the enduring puzzles about concealed ovulation: It is one thing for ovulation to be hidden from others, but why in Darwin’s name should such important, biologically crucial information be kept from the woman herself? Why is this such a deep, dark secret, one that cannot even be shared with the person who presumably has—if not a legal or moral right to the information—at least a deep personal stake in obtaining it? And finally, this last hypothesis is somewhat counterintuitive and therefore great fun to examine.
     
    It was first suggested by Nancy Burley, an evolutionary biologist currently at the University of California, Irvine. 11 Let’s assume that far enough back in the human evolutionary line, there was a range of self-awareness when it came to one’s own ovulation, as there is for most things: Some women could tell when they were fertile, others—at the other extreme of the distribution—had little or no idea, and in between there was a range of ovulatory self-consciousness. Add to this the fact that among many traditional peoples today (hunter-gatherers and other members of nontechnological societies), women want fewer children than men do, mostly because of the downsides of pregnancy and childbirth, especially in an environmentlacking biomedical sophistication. The result is the following prospect: If, like today’s hunter-gatherers, our ancestral grandmothers disagreed with their mates in wanting fewer offspring, then those who detected their own “time of the month” might well have made special efforts at those times to fend off the advances of our would-be ancestral grandfathers. Call it the headache hypothesis.
    By succeeding in limiting their reproduction, such women would unknowingly have sabotaged the self-awareness system in which they participated. Who would have gotten pregnant? Not those who could detect their own ovulation, but those who couldn’t, who were unaware of what was going on inside their own bodies. A case of matter over mind. Our maternal ancestors would thus have been those who didn’t reveal cues as to whether they were ovulating but who also couldn’t even tell, themselves.
Breasts: Outlining the Mystery
     
    Next, our attention turns to breasts. In the process, we have plenty of company. Whereas the mystery of ovulation is why it is so secret, the breast question is exactly the opposite: Why so obvious? Whereas ovulation is mysterious because something so important is so hidden, breasts are mysterious because something so unimportant (most of the time) is so prominent (most of the time) and gets so much undeserved attention (nearly all the time).
     
    The most straightforward explanation for why women have prominent breasts even when not lactating is that they signal capacity to nourish offspring, so that bustier women would have been preferentially chosen by would-be fathers. But why hasn’t a similar process operated in other mammals? Except for human beings, there are no mammals in which nonlactating