I am now writing a weekly column in the Wall Street Journal
called Mind and Matter. Here’s the first one.
Recently, the psychologist David Buss’s team
at the University of Texas at Austin reported that men, when
looking for one-night stands, check out women’s bodies. Or as they
put it, “men, but not women, have a condition-dependent adaptive
proclivity to prioritize facial cues in long-term mating contexts,
but shift their priorities toward bodily cues in short-term mating
contexts.”
Like many results in evolutionary psychology,
this may seem blindingly obvious, but that does not stop it from
being controversial. Earlier this month a neuroscientist in
Britain, Gina Rippon, lambasted what she called the “neurohype”
about sex differences: “There may be some very small differences
between the genders, but the similarities are far, far
greater.”
She has a point. Compared with, say,
chimpanzees, men and women are not very different. Most of the
interesting things about people-language, laughter, love,
laptops-come just as naturally to both sexes.
Yet we would be a very peculiar animal
species if we did not have sex differences in behavior as well as
anatomy. In virtually every mammal and nearly all birds, males are
more aggressive, females more nurturing. It is a distinction that
goes right back to active sperm competing for stationary eggs in
the primeval ocean. It was only reinforced when the invention of
the placenta and the mammary gland gave male mammals a gigantic
prize to compete for: nine months and several years of somebody
else’s bodily efforts. Wombs are worth fighting over-and granting
to favored applicants only.
So it’s no zoological accident that in all
societies, however peaceful or violent, men are about 50 times more
likely to kill other men than women are to kill women, and they do
so most in young adulthood, when most actively competing for mates.
Likewise, it is no neurophysiological accident that women coo over
newborn babies more enthusiastically than men do. Women who showed
interest in babies left more genes behind than those who were
indifferent; men who turned violent left more genes.
These are the kinds of sex differences that
we share with all other mammals. What intrigues me, though, is the
possibility that human beings have other sex differences peculiar
to themselves and derived from uniquely human habits of more recent
origin.
Take the cliché of the golf-playing husband
and the shoe-shopping wife. Not even an evolutionary psychologist
would claim to find monkey equivalents to this. Yet the obsession
with the trajectory of ballistic objects is as baffling to most
women as the obsession with searching and re-searching every store
for the perfect shoe bargain is to men. (I know there are
exceptions, but admit it: Marriage surprises most people by
revealing the truth of such clichés.)
In all hunter-gatherer societies there is a
sharp difference between the foraging strategies of the two sexes.
Men generally travel far in search of mobile prey that they need to
bring down with well-aimed projectiles. Women generally go out in
groups and search for good sources of roots, ripe berries or nuts,
which they use their acute powers of observation to spot and
collect.
Without knowing it, golf-course designers are
setting up a sort of idealized abstraction of the hunting ground,
while shoe retailers are setting up a sort of ersatz echo of the
gathering field.
This sexual division of labor over foraging
is not only far more marked in people than in most other animals
(it was, arguably, the first “gain from trade” we stumbled upon,
benefitting both sides), but it may be a relatively recent feature
of our evolutionary history, invented in Africa just 150,000 to
300,000 years ago. Some archaeologists have concluded that
Neanderthals did not practice it: that female Neanderthals were
co-operative hunters with men, not gatherers.
That still gave the sexual division of labor
plenty of time to leave its instinctive marks on the human psyche
through genetic changes, raising the intriguing thought that some
of our sex differences might be caused by our culture, yet also
ingrained in our genes.