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It is not the peacock with big-enough tail that gets to mate, but the one with the biggest tail

My latest Mind and Matter column in the Wall
Street Journal is on the connection between our interest in
relative inequality and the theory of sexual selection:

Evolution by sexual selection is an idea that goes back to
Charles Darwin. He had little doubt that it explained much about
human beings, and modern biologists generally agree. One of them
has even put a figure on it, concluding that some 54.8% of
selection in human beings is effectively caused by reproduction of
the sexiest rather than survival of the fittest.

Some years ago, the evolutionary psychologist Geoffrey Miller in
his book “The Mating Mind” explored the notion that since human
males woo their mates with art, poetry, music and humor, as well as
with brawn, much of the expansion of our brain may have been
sexually selected.

Recently Jason Collins and two colleagues at the University of
Western Australia, in a discussion paper posted on the Web, have made
the case that sexual selection explains civilization itself. They
mathematically explored the possibility that “as females prefer
males who conspicuously consume, an increasing proportion of males
engage in innovation, labor and other productive activities in
order to engage in conspicuous consumption. These activities
contribute to technological progress and economic growth.”

Psychological evidence points the same way. In one experiment,
men who were shown pictures of women promptly expressed more
extravagant desires for expensive luxuries, whereas women showed no
such effect after seeing pictures of men. There’s historical
evidence, too. As Aristotle Onassis is supposed to have said, “If
women did not exist, all the money in the world would have no

Moreover, Michael Shermer, in his book “The Mind of the Market,”
argues that you can trace anticapitalist egalitarianism to sexual
selection. Back in the hunter-gatherer Paleolithic, inequality had
reproductive consequences. The successful hunter, providing
valuable protein for females, got a lot more mating opportunities
than the unsuccessful. So it’s possible that men still walk around
with a relatively simple equation in their brains, namely that
relative success at obtaining assets results in more sexual
adventures and more grandchildren.

If so, this might explain why it is relative, rather than
absolute, inequality that matters so much to people today. In
modern Western society, when even relatively poor people have
access to transport, refrigeration, entertainment, shoes and
plentiful food, you might expect that inequality would be less
resented than a century ago-when none of those things might come
within the reach of a poor person. What does it matter if there are
people who can afford private jets and designer dresses?

But clearly that isn’t how people think. They resent inequality
in luxuries just as much if not more than inequality in
necessities. They dislike (and envy) conspicuous consumption, even
if it impinges on them not at all. What hurts is not that somebody
is rich, but that he is richer.

This is a classic statement of sexual selection. It isn’t the
peacock with the big-enough tail that gets to mate; it’s the
peacock with the biggest tail. If this sounds old-fashioned in an
age of working women, gender equality and relative sexual
continence, then open your eyes and look around you: The man with
the most money or power still gets more sexual opportunities than
the man with the least. AskĀ David Petraeus.

In human beings, females compete for males as well as vice
versa. In many species, sexual selection is a force that acts on
only one sex, usually the male. Peahens, which can share the best
males and don’t require them to be diligent parents after mating,
do not grow colorful tails. But in other species, notably some
seabirds and parrots, where males and females share parenting
duties equally, both sexes are equally colorful-a result of
competition by both sexes to attract the best mates.

By Matt Ridley | Tagged:  rational-optimist  wall-street-journal