The Definitive Guide to the Evolutionary Biology of Sex


What the Critics Say About Dr. Tatiana's Sex Advice to All Creation

New York Times - Nicholas Wade

A Racy Guide to Evolution

"Dear Dr. Tatiana,

My name's Twiggy, and I'm a stick insect. It's with great embarrassment that I write to you while copulating, but my mate and I have been copulating for 10 weeks already. I'm bored out of my skull, yet he shows no sign of flagging. . . . How can I get him to quit?

Sick of Sex in India."

Dr. Tatiana is the pen name of Dr. Judson, an evolutionary biologist who has discovered that an advice columnist's pose is a deft device for discussing the mating game's many amazing variations in nature.

In the replies to her finned, furred and feathered correspondents, titled "Dr. Tatiana's Sex Advice to All Creation," she counsels creatures caught in the most curious predicaments, from a fig wasp in Ribeirao Preto, Brazil, concerned that her lovers keep decapitating one another, to an elephant in Amboseli in Kenya bothered that his penis had turned green, to a male bronze-winged jacana bird of Tamil Nadu, India, cruelly neglected by the female who keeps him in her harem.

Beneath these racy tales and the saucy advice offered for their solutions, a less visible agenda is at work. The reader is nudged to start thinking like an evolutionary biologist. Why did this bizarre behavior evolve and what advantage does it confer? Does the male stick insect copulate for 10 weeks because he has nothing better to do with his time or could it be to prevent other males from fertilizing his inamorata's eggs?

Eggs are few, and sperm are many. This microscopic-level asymmetry is the root cause of ardent civil war that in every species pits male against male, and male against female. Males, from sea lions and fruit bats to to Taliban, are driven to control females' fertility so as to ensure their own paternity.

But a female's interest usually lies in having many lovers. There are many sound reasons for the female to pursue a policy of determined promiscuity, Dr. Tatiana informs a male yellow dung fly of 12, including to guard against male sterility, to ensure diversity in her offspring, to encourage each male in her group to think that he is the father and protect her children accordingly and to encourage competition among the sperm of several males so as to ensure her egg gets the best.

"Natural selection, it seems, often smiles on strumpets," Dr. Tatiana writes without much hint of regret. "Sorry, boys."

Despite Dr. Tatiana's dark and worldly wisdom, her creator is a fair-haired young woman with an infectious laugh. Dr. Judson studied biology at Stanford and at the University of Oxford in England, where she was one of the last students of Dr. William D. Hamilton, whose theory of kin selection undergirds large arenas of modern biology, including sociobiology and evolutionary psychology. In 2000, he died of malaria that he caught after a trip to Congo to investigate a hypothesis about the origin of AIDS.

In an interview, Dr. Judson recalled her mentor's imaginative gift for entering the minds of the insects he studied.

Once she asked him about the biology of a species of asexual weevil. A few days later, a pinned specimen arrived in her mailbox.

But there was the occasional disagreement. "I once had an argument with him," she said. "I burst into floods of tears, and he sat staring at his toes."

Dr. Hamilton was famously impractical. University administrators required him to give just one lecture a year. But on at least one occasion he forgot even that. As a profound evolutionary thinker, Dr. Hamilton knew the difference between a sex symbol and the real thing.

After he received a prestigious scientific prize with a big cash award, there was a dinner in his honor. "One of his friends said," Dr. Judson recalled, " `Bill, I expected you to arrive in a Ferrari.' " He replied to the effect that he thought of arriving with a couple of young women.

Dr. Judson's foray into writing occurred despite some early discouragement. As a child, she knew that writing must be an arduous profession because of the occasional tortured groan she heard emanating from the study of her father, Horace Judson, a historian of molecular biology.

At Oxford, she started writing articles for The Economist. The pseudonym Dr. Tatiana first materialized when, as a joke on the business affairs editor, she put on a disguise and posed as a candidate for an interview that lasted until his questions grew too uncomfortably technical.

Dr. Tatiana's advice is never too technical. But beneath the levity and romps, it raises some deeper issues. After surveying the baroque variety of sexual arrangements in the animal world, she concludes that the least common, the very weirdest of all, is monogamy. A handful of species practice it, like the chin-strap penguin, the long-eared owl, the mantis shrimp, a few termites and the black vulture.

Monogamy is so rare, Dr. Tatiana suggests, because it can evolve only in the special styles of life where male and female interests are perfectly aligned and where stable couples leave more offspring than cheaters.

An observer of the many draconian laws and sanctions that society has developed to enforce monogamy would be hard pressed to declare it the default condition of humankind.

Humans have telltale signs in their physiology like the male's largish testes and the size difference between the sexes that indicate that their natural propensity is mildly promiscuous.

There are no people among Dr. Tatiana's ark of correspondents, although human biology is mentioned in passing, in part because of what she considers the unreliability of information about their sexual behavior. People mislead researchers on questionnaires and can conceal their dalliances with abortions and contraceptives.

"I tried as much as I could to stick to studies which are rigorously done," Dr. Judson says.

The ultimate mystery is how sex started and why it is necessary. The immediate purpose of sex, as everyone knows, is to provide new combinations of well-tested genes. Hence sex is the perfect complement to mutation, which engenders novel genes. But meiosis, the cellular quadrille that produces the egg and sperm cells, is a highly complicated and burdensome dance, and many species have reverted to simple asexuality.

Virgin birth is no ticket to longevity. Most asexual species become extinct after a time. That might confirm the notion that sex is an absolute necessity in the long run, but for the puzzling existence of the bdelloid rotifer, a species that has been asexual for 85 million years.

Bdelloid rotifers, however, have a special trick not shared by sexually reproducing rotifers. They can dehydrate themselves when their pond dries up and blow away on the wind. Such a disappearing act has the advantage of leaving parasites far behind.

Dr. Tatiana notes that another longtime asexual species, the fungus cultivated in the gardens of Attine ants, is also dispersed by a method that lets it escape from its deadliest parasite. Young queen Attines select a parasite-free sample of fungus for founding their new nests. These facts lend support to the Red Queen theory of sex, that its purpose is to help a species keep reinventing itself and stay one step ahead of its parasites.

Whatever the reason for the sex, nature has developed so many variations on the theme that it is hard to discern any clear moral or imperative, let alone any support for the idea that what is natural must be right. Even Dr. Tatiana is at a loss.

"When it comes to the topic of gender," she concludes, "Mother Nature's been having some fun. Take nothing for granted! Remember, You won't find any rules - not a one!"