Cupid's science

You're talking about all this hormonal response, but how does that relate to someone you meet over an Internet connection?

HF: A lot of people think that Internet dating is unnatural, but I think it is extremely natural, because for millions of years, you might not know that cute boy over at the water hole, but your mother knows his aunt, and you know a lot about him: what he's going to grow up to become, who his relatives are, what his religion is; you know things about him. It's really much more artificial to walk into a bar where you know nothing about the person.

IK: One trend I've noticed lately online is people being much more interested in people's educational backgrounds.

HF: Yeah, particularly men. Men didn't care about women's educational backgrounds in the past. Now they care.

Do they want women to have more or less education than they have?

IK: Equal or superior. It's not the traditional: "Oh my God, she's making more money than me, my ego has been shattered." It's more like, "This is a two-income world we live in, it's going to take both of us to make it."

HF: They also want women closer to their age, and want them to have the same earning power. But you know what? It's not different from the way we always were. We're moving forward toward the kind of people we were a million years ago. For millions of years women commuted to work to gather vegetables, they came home with 60 to 80 percent of the evening meal, the double-income family was the rule. In shedding what we regard as traditional family values, we're actually going back to the real traditional configurations.

What screwed up that balance originally?

HF: Somebody invented the plow. Prior to the plow, women in horticultural societies did the farming with a digging stick and were very powerful. But somebody invented the plow about 5,000 years ago, and it required the strength of men; men began to need to move the rocks, fell the trees, draft big heavy animals. Then the property that got produced was more theirs, and they would bring it to local markets and come back with the equivalent of money. Women got relegated to secondary jobs and having lots of babies, because in farming societies, you needed children as the workforce.

IK: Changing subjects for a minute, I wanted to ask Helen about the fact that my wife says to me, "The only reason I'm still with you is that I like the way you smell." For all the mate-matching systems, aren't there always going to be these intangibles?

HF: Always. I finish my talks by saying "there will always be magic to love." All I'm trying to do is add another component to the mystery. But you never can predict. There could be some tiny aspect of your childhood that will turn you one way or another in love.

IK: Even the smell thing is a genetic index, so if I'm attracted to your smell we're most likely to create the most genetically broad, healthy children. People should be submitting T-shirts to Chemistry.

HF: Somebody actually came to me with a proposal! What I'm discovering on the site is how much you can read someone's face. We know you can read testosterone signs: the heavy jaw, heavy brow ridge, and little round face for estrogen. What we will do eventually is figure out how serotonin and dopamine express themselves physically. I'm interested in the smell thing, but they call it love at first sight because 80 percent of the brain is devoted to the visual.

IK: What do you think about a generation of single people who are on SSRIs? Are they spiking their dopamine and messing with their brain chemistry?

HF: Yes. At the university I'm working with, 40 percent of incoming freshmen are on something. Ritalin for fun, androgens to build the body, SSRIs.

And you say that antidepressants not only have sexual side effects but that they dull the brain's ability to feel love?

HF: Yes, I wrote about it [with psychiatrist J. Anderson Thomson] in a chapter in the book "Evolutionary Cognitive Neuroscience."

IK: I think you're on to something, because anecdotally I meet a lot of single people on antidepressants and I would say their mating systems are very impaired. That's 40 percent of my clientele -- when one person is on an antidepressant. And I hear from lots of people whose psychiatrists or G.P.s never even mentioned the sexual side effects before prescribing.

HF: I give speeches to grand rounds at hospitals, and at an uptown hospital a guy took me to the cleaners for [talking about the way that SSRIs alter the way the brain responds to love]. People don't hear what I'm saying. For some people these are necessary drugs. There are people who can't get out of bed to go on a date; they need antidepressants! I'm just saying that we could at least tell people it's a possibility that they're altering how they feel love.

Can you talk at all about anthropological and biological models for matchmaking? Are there yentas in the animal kingdom, matchmakers in nature?

HF: I've looked at 100 species and I think we've evolved three different brain systems -- sex drive, romantic love, and attachment, the deep sense of calm and security you can feel over the long term. Animals have all three systems. Now, 97 percent of animals do not pair up to rear their young; only 3 percent do. So they probably have a stronger attraction system and maybe romantic love, but not as strong attachment systems.

But an elephant will, at the beginning of her estrus, avoid a lot of males and then she'll suddenly see one who's the right guy and make a beeline for him. Then she'll show many of the characteristics that, if you listed them in a human being, you would say she's in love: doggedly following him; focused attention on the fact that this particular male is special -- if he had three heads she wouldn't notice -- all kinds of affiliative gestures, like putting her trunk on his back; not eating; not sleeping; she'll be just overcome by infatuation for this fella. So no, I don't think other female elephants are lumbering through as matchmakers, saying, "He's not good for you!" But don't forget that many females raise their babies on their own. So what they really need is insemination by the best-looking, strongest, smartest, least scruffy guy.

Given the number of single mothers, could humans be heading toward a model in which women raise their babies on their own and just need insemination from the smartest, least scruffy male?

HF: I don't think so. Our brain system for attachment is so strong.

IK: On the other hand, I send my son to a school where a percentage of moms chose to be artificially inseminated or have a sperm donor. They are very successful in their careers, money is not really an issue, and they're raising their children on their own.

HF: But I would guess that if the right guy came along ... Look: One-third of all children in America are born out of wedlock; teen births are going down, but older women are choosing to have the babies on their own and then marrying the guy or marrying a different guy. But 90 percent of Americans do marry by middle age. We're just marrying later and doing more serial pair bonding.

I know that eHarmony's goal is to lower the divorce rate, and PerfectMatch's is to make practical long-term partnerships. Are you interested in creating marriages?

HF: Chemistry.com was designed for people interested in a long-term relationship. But we feel that a lot of these other sites are behind the times in looking only for marriage, that there are many, many ways to have a beautiful long-term relationship that does not include marriage.

Next page: Do you use the same model for gay and straight matchmaking?