Oh, great. She was one of those "teachers" who had to have a goat in the class—someone to torment in order to score points.

"No, ma'am," said John Paul. "I came here hoping that you'd teach me everything about it." He kept every trace of sarcasm out of his tone; but of course that made it even more barbed and condescending.

He expected her to show annoyance at him, but instead she merely turned to another student and began a dialogue. So either John Paul had scared her off, or she had been oblivious to his sarcasm and therefore had no idea she had been challenged.

The class wouldn't even be interesting as a blood sport. Too bad.

" 'Human evolution is driven by community needs,' " she read from the board. "How is that possible, since genetic information is passed only by and to individuals?"

She was answered by the normal undergraduate silence. Fear of appearing stupid? Fear of seeming to care? Fear of seeming to be a suck-up? Of course, a few of the silent students were honestly stupid or apathetic, but most of them lived fear-driven lives.

Finally a tentative hand went up.

"Do communities, um, influence sexual selection? Like slanting eyes?"

"They do," said Miss Grad Student, "and the prevalence of the epicanthic fold in East Asia is a good example of that. But ultimately that's trivial—there is no actual survival value in it. I'm talking about good old rock-solid survival of the fittest. How can that be controlled by the community?"

"Killing people who don't fit in?" suggested another student.

John Paul slid down in his seat and stared at the ceiling. This far into their education, and they still had no understanding of basic principles.

"Mr. Wiggin seems to be bored with our discussion," said Miss Grad Student.

John Paul opened his eyes and scanned the board again. Ah, she had written her name there. Theresa Brown. "Yes, Ms. Brown, I am," he said.

"Is this because you know the answer, or because you don't care?"

"I don't know the answer," said John Paul, "but neither does anyone else in the room except you, so until you decide to tell us instead of engaging in this enchanting voyage of discovery in which you let the passengers steer the ship, it's naptime."

There were a few gasps and a couple of chuckles.

"So you have no ideas about how the statement on the board might be either true or false?"

"I suppose," said John Paul, "that the theory you're suggesting is that because living in communities makes humans far more likely to survive, and to have opportunities to mate, and to bring their children to adulthood, then whatever individual human traits strengthen the community will, in the long run, be the ones most likely to get passed along to each new generation."

She blinked. "Yes," she said. "That's right." And then she blinked again. Apparently he had interrupted her lesson plan by getting to the answer immediately.

"But what I wonder," said John Paul, "is this: Since human communities depend on adaptability in order to thrive, then it isn't just one set of traits that strengthen the community. So community life should promote variety, not a narrow range of traits."

"That would be true," said Ms. Brown, "and indeed is true in the main, except that there are only a few types of human communities that actually survive long enough to improve the chances of individual survival."

She walked to the board and wiped out a swath of material that John Paul had just blown through by cutting to the chase. In its place, she wrote two headings: Tribal and Civil.

"There are two models that all successful human communities follow," she said. Then she turned to John Paul. "How would you define a 'successful' community, Mr. Wiggin?"

"One that maximized the ability of its members to survive and reproduce," he said.

"Oh, if only that were true," she said. "But it's not true. Most human communities demand antisurvival behavior from large numbers of their members. The obvious example would be war, in which members of a community risk their own death—usually at the very age when they are about to begin family life. Many of them die. How can you possibly pass on the willingness to die before reproduction? Those who have this trait are the least likely to reproduce."

"But only males," said John Paul.

"There are women in the military, Mr. Wiggin."

"In very small numbers," said John Paul, "because the traits that make good soldiers are far less common in women, and the willingness to go to war is rare in women."

"Women fight savagely and die willingly to protect their children," said Ms. Brown.

"Exactly—their children. Not the community as a whole," said John Paul. He was making this up as he went along, but it made sense and was interesting—so he was quite willing to let her play the Socratic questioning game.

"And yet women are the ones who form the tightest community bonds," she said.

"And the most rigid hierarchies," said John Paul. "But they do it by social sanctions, not by violence."

"So you're saying that violence in males but civility in women is promoted by community life."

"Not violence," said John Paul. "But the willingness to sacrifice for a cause."

"In other words," said Ms. Brown, "men believe the stories their communities tell them. Enough to die and kill. And women don't?"

"They believe them enough to..." John Paul paused a moment, thinking back on what he knew about learned and unlearned sex differences. "Women have to be willing to raise their sons in a community that might require them to die. So men and women all have to believe the story."

"And the story they believe," said Ms. Brown, "is that males are expendable and females are not."

"To a degree, anyway."

"And why would this be a useful story for a community to believe?" She directed this question to the class at large.

And the answers came quickly enough, because some of the students, at least, were following the conversation. "Because even if half the men die, all the women will still be able to reproduce."

"Because it provides an outlet for male aggressiveness." "Because you have to be able to defend the community's resources."

John Paul watched as Theresa Brown fielded each response and riffed on it.

"Do communities that suffered terrible losses in war in fact abandon monogamy or do a large number of women live their lives without reproducing?" She had the example of France, Germany, and Britain after the bloodletting of World War I.

"Does war come about because of male aggressiveness? Or is male aggressiveness a trait that communities have to promote in order to win wars? Is it the community that drives the trait, or the trait that drives the community?" Which John Paul realized was the very crux of the theory she was putting forth—and he rather liked the question.

"And what," she finally asked, "are the resources a community has to protect?"

Food, they said. Water. Shelter. But these obvious answers did not seem to be what she was looking for. "All these are important, but you're missing the most important one."

To his own surprise, John Paul found himself wanting to come up with the right answer. He had never expected to feel that way in a class taught by a grad student.

What community resource could be more important to the survival of the community than food, water, or shelter?

He raised his hand.

"Mr. Wiggin seems to think he knows." She looked at him.

"Wombs," he said.

"As a community resource," she said.

"As the community," said John Paul. "Women are community."

She smiled. "That is the great secret."

There were howls of protest from other students. About how men have always run most communities. How women were treated like property.

"Some men," she answered. "Most men are treated far more like property than women. Because women are almost never simply thrown away, while men are thrown away by the thousands in time of war."