Sex and science have become entangled again in the news, which gives me an excuse to look into the latest research on men, women and promiscuity. It all started when The New York Times ran a piece called "Darwin was Wrong about Dating" in the Sunday Review section. The story wasn't really about Darwin or dating, but about some new studies that suggested women behave more like men (or Sex and the City characters) than previously assumed by the scientific community.

The truth is still under investigation. Human behavior is hard to study, especially when it comes to sex. Men and women are often under tremendous cultural pressure to behave as they think their respected sexes should. There's a lively debate about sex differences in promiscuity, desire for sex and choosiness. And there's discussion of the relative roles of culture and biology in shaping human behavior.

But there was something badly amiss about this New York Times piece, which I explained briefly in a critique for the Knight Science Journalism Tracker. Problem #1 – the headline. When journalists start a story or headline with the phrase "Darwin was Wrong," I suspect they're trying too hard to get attention. The implication is that Darwin was wrong about evolution by natural selection, which of course he was not.

As for dating, Darwin wasn't really much of a guru – or even into the dating scene himself. According to his own autobiographical writings, he was pretty fixated in his work as a naturalist in his 20s and early 30s, though he decided eventually to marry his cousin. What the New York Times takes as backing for Darwin's dating wrongness is an infamous quote, often used by creationists, taken from The Descent of Man. There, Darwin wrote that men are more "inventive" and women more "nurturing."

Darwin also suggested that natural selection shapes not only the bodies of animals but their behavior, and since humans are animals, this is true for us as well. A whole field known as evolutionary psychology has sprung up to investigate this evolution/behavior connection. The Times author tries to make a case that Darwin was wrong about behavior and that evolutionary psychology is bunk.

Using a Fake Polygraph to Bring out the Truth

As evidence for his case, the author brings in these newer studies on human sexuality, which suggest women are more promiscuous than they let on in previous studies. Does this have anything at all to do with Darwin's contention that evolution shapes behavior? To find out, I called one of the authors one of these allegedly Darwin-challenging studies.

Ohio State University psychologist Terri Fisher led a study that involved a fake lie detector. Men and women thought it was being used on them as they answered questions about the number of sex partners they'd had. In some previous surveys, men tended to claim more sexual partners than women, but when subjects thought the machine was catching their fibs, they reported about the same number.

That makes perfect sense, because every time a man adds a notch to his bedpost, a woman will get a new notch on hers as well.

Fisher also used the fake lie detector test while asking people how old they were when they had sex for the first time. She said she was dubious about results of previous surveys in which many men reported having their first intercourse at 12 or 13, while very few women reported having sex that young. Who were these young boys having sex with, if not young girls? There are cases of adult women having sex with boys that age, but she suspected it was rare. And, indeed, when people thought they were hooked up to a lie detector, the sex difference disappeared there as well.

The first thing I asked Fisher was whether she thought Darwin was right that evolution influences human behavior. "Certainly," she said. "I think it would be hard to find any psychologists who didn't accept that premise."

"Where we might differ is in the degree to which results of evolution manifest themselves in behavior today."

One reason there's disagreement over the role of evolution in human sexuality is that we're so powerfully influenced by culture, and U.S. culture puts pressure on men to have sex early and often, and on women not to come across as "slutty".

This pressure could explain why men and women tend to even out in their answers when they think someone can detect lies.

Fisher doesn't think there's anything in her results that contradicts the notion that evolution influenced human behavior. DNA testing, Fisher said, has shown that many seemingly monogamous female birds have offspring by males other than the ones scientists assumed were the father. Evolution can produce monogamous, promiscuous or cheating type behavior in other animals. But what kind of an animal are we?

Women are Complicated. Science says Men are too.

We are unique in some ways. While sexual behavior in most species is pretty uniform – alley cats will be alley cats and penguins will be penguins – individual humans are all over the map. Psychologists don't so much find rules for how men or women will behave but patterns. Humans of both sexes can be extremely monogamous, mating with one person for 60 years, or they can have sex with hundreds or even thousands of different partners. "That's something that gets lost in thediscussion ...the degree of sexual variability within genders," she said.

In surveys, both men and women vary enormously in the number of sexual partners they say they would like. Variation showed up again in another study cited in the New York Times piece - one in which attractive young psychology students asked a series of opposite-sex passers-by whether they would go on a date, whether they would go to the person's apartment and whether they would like to have sex. Women often agreed to the date but rarely agreed to the sex. 70% of men agreed to the sex.

But to me it's fascinating that 30% of men said no to a gorgeous woman offering free sex. I may be a glass 30% full kind of person, I suppose, but that seems to disprove the anti-male sexist remark that "all men are alike". Some of those 30% of naysayers among the men might been gay, but others might have been faithful to a partner, or they might have had enough depth of character to want more than just a pretty face in a lover.

Fisher also did a study to measure how many times a day men and women really think about sex. As expected, the men thought about sex more often than the women, but the variation was remarkable. "There were men who reported thinking about sex once a day, hundreds of times a day and everything in between," she said.

We're tricky animals to pin down. But we're still animals and it would be extraordinary if we were magically immune to the same evolutionary forces that shape the behavior of other animals.

It's a step in the right direction that people such as Dr. Fisher are continuing to add to our understanding, and to find really clever – and inventive – ways sort through the pervasive influence of culture. Lacking a full understanding of culture might have tripped up Darwin in some details, but not in seeing the big picture.