Those results seemed definitive — until a few years ago, when Terri D. Conley, a psychologist at the University of Michigan, set out to re-examine what she calls “one of the largest documented sexuality gender differences,” that men have a greater interest in casual sex than women.

Ms. Conley found the methodology of the 1989 paper to be less than ideal. “No one really comes up to you in the middle of the quad and asks, ‘Will you have sex with me?’ ” she told me recently. “So there needs to be a context for it. If you ask people what they would do in a specific situation, that’s a far more accurate way of getting responses.” In her study, when men and women considered offers of casual sex from famous people, or offers from close friends whom they were told were good in bed, the gender differences in acceptance of casual-sex proposals evaporated nearly to zero.

IN light of this new research, will Darwinians consider revising their theories to reflect the possibility that our mating behavior is less hard-wired than they had believed?

Probably not. In an article responding to the new studies last year, Mr. Schmitt, a leading voice among hard-line Darwinians, ceded no ground. Addressing Ms. Conley’s finding that women were more likely to agree to casual sex with a celebrity, Mr. Schmitt argued that this resulted from “women’s (but not men’s) short-term mating psychology being specially designed to obtain good genes from physically attractive short-term partners.” He continued: “When women’s short-term-mating aim is activated (perhaps, temporarily, because of, e.g., high-fertility ovulatory status or desire for an extramarital affair, or more chronically, because of , e.g., a female-biased local sex ratio or a history of insecure parent-child attachment), they appear to express relatively focused desires for genetic traits in ‘sexy men’ that would biologically benefit women when short-term mating.”

In other words: Nothing new here, it’s all evolution.

Steven Pinker, the Harvard psychologist and popular author, also backs the Darwinians, whom he says still have the weight of evidence on their side. “A study which shows you can push some phenomenon around a bit at the margins,” he wrote to me in an e-mail, “is of dubious relevance to whether the phenomenon exists.”

But the fact that some gender differences can be manipulated, if not eliminated, by controlling for cultural norms suggests that the explanatory power of evolution can’t sustain itself when applied to mating behavior. This wouldn’t be the first time we’ve pushed these theories too far. How many stereotypical racial and ethnic differences, once declared evolutionarily determined under the banner of science, have been revealed instead as vestiges of power dynamics from earlier societies?

Citing the speed-dating study, Mr. Pinker added, “The only reason this flawed paper was published was that it challenged an evolutionary hypothesis ... in particular a sex difference — as the Larry Summers incident shows, claims about sex differences are still politically inflammatory in the academy.” Here, he was referring to the much criticized 2005 comments Mr. Summers made when he was Harvard’s president suggesting that women’s underrepresentation in science and engineering was attributable not to socialization but to “different availability of aptitude at the high end.”