Palestinians to America, societies set great
value on chastity or some measure of propriety or reserve in women.
Evidence like this piles up in Buss’s pages. And
then he adds another worldwide mating reality—that from Zambia to America,
financial prospects are prized in men—and this takes him to one of evolutionary
psychology’s pivotal conceits. Within the field, it is known as “parental
investment theory.” To the public, it may not be known by any name at all. And
by most, the theory’s components may be only hazily comprehended. Yet the
conceit has traveled from academia through the media and into general
consciousness. It has been fully embraced, deeply absorbed, become part of
common wisdom. Parental investment theory goes like this: because men have
limitless sperm while women have limited eggs, because men don’t have to invest
much of worth in reproduction while women invest not only their ova but their
bodies, as they take on the tolls and risks of pregnancy and childbirth, because
women then invest further in breast-feeding (the investment being in time, in
extra calories required, and in the postponed ability to conceive another
child)—because of this economy of input, far more pressingly relevant to our
prehistoric ancestors, to our ever-endangered forebears, than to the humans of
today, males have been programmed, since way back when, to ensure and expand
their genetic legacy by spreading their cheap seed, while females have been
scripted to maximize their investment by being choosy, by securing a male likely
to have good genes and be a good long-term provider to her and her
offspring.
This all fits neatly with the evidence from Zambia,
Yugoslavia, Palestinian towns, Australia, America, Japan. And the theory’s stark
economic terms have a solid, incontrovertible sound. Our erotic beings, the
differences in desire we observe between the genders, are the inevitable
manifestations of evolutionary forces from eons ago. Parental investment theory
gratifies one of our urgent longings: for simple answers about how we’ve come to
be the way we are.
But the theory’s foundation is precarious at best.
Does the fact that women are expected to be the more demure gender in Lusaka and
New York, in Kabul and Kandahar and Karachi and Kansas City, prove anything
about our erotic hardwiring? Might the shared value placed on female modesty
speak less to absolutes of biology than to the world’s span of male-dominated
cultures and historic suspicion and fear of female sexuality?
And then, what of Chivers’s plethysmograph, which
made a myth out of appearances? What of the drives that lie concealed beneath
the surface, that crouch within the strictures? The sexual insights of
evolutionary psychology can sometimes seem nothing but a conservative fable,
conservative perhaps inadvertently but nevertheless preservationist in spirit,
protective of a sexual status quo. Women, the fable teaches, are naturally the more restrained sex; this is the inborn
norm; this is normal. And the normal always wields a self-confirming and
self-perpetuating power. Because few people like to defy it, to stray from
it.
One recent pop psychology mega-seller, The Female Brain , opens with lessons grounded in
parental investment theory and serves as an emblem of the ways evolutionary
psychology has spread its sexual vision throughout the culture. “The girl brain”
is a “machine built for connection,” for attachment. “That’s what it drives a
female to do from birth. This is the result of millennia of genetic and
evolutionary hardwiring.” The boy brain-machine is very different; it is built
for “frenzies” of lust.
The book, like loads of others in the pop
psychology genre, pretends to back its evolutionary theory with something
concrete, with the technology known as functional magnetic resonance imaging,
fMRI—with pictures of the brain at work. But the technology is nowhere near
being up to the task. To spend time in