‘secrets of sexual attraction’

The Post had an interesting article, reprinted from New Scientist magazine, that looked at picking a mate from a scientific perspective:

As a scientist studying human behavior, I am not too surprised by the mysterious nature of how we go about choosing a partner. Mate selection is a highly complex process. We are consciously aware of only part of it; the rest is either inherently unpredictable or operates outside our awareness, which leads us to the perception that love is about ineffable chemistry. …

What about the less obvious cues of attraction? Fascinating work on genetics and mate preferences has shown that each of us will be attracted to people who possess a particular set of genes, known as the major histocompatibility complex (MHC), which play a critical role in our ability to fight pathogens. Mates with dissimilar MHC genes produce healthier offspring with broad immune systems. And the evidence shows that we are inclined to choose people who suit us in this way: couples tend to be less similar in their MHC than if they had been paired randomly.

How do people who differ in their MHC find each other? This isn’t fully understood, but we know that smell is an important cue. People appear to literally sniff out their mates. In studies, people tend to rate the scent of T-shirts worn by others with dissimilar MHC as most attractive. This is what sexual “chemistry” is all about.

The message here is trust your instincts – except that there is an alarming exception. For women taking hormonal contraceptives, the reverse is true: they prefer men whose MHC genes are similar to their own. Thus women on the Pill risk choosing a mate who is not genetically suitable (best to smell him first and go on the Pill afterward). This is a prime example of how chemical attraction can depend on your circumstances. …

But that still poses the question, if the roads to love are so varied and random, how do we decide on a particular mate? It turns out that the problem of choice under uncertainty can be described and solved mathematically.

Evolutionary psychologists Peter Todd at Indiana University in Bloomington and Geoffrey Miller at the University of New Mexico used a computer simulation to determine how a person might best choose from a number of potential partners. They set it up so that the person first assesses a number of the options before them to decide what is the best they can aspire to in terms of attractiveness, and then goes for the next person they come across who meets their aspirations out of those they haven’t already encountered.

The researchers found that the optimum proportion of possible mates to examine before setting your aspirations and making your choice is a mere 9 percent: So at a party with 100 possible mates, it’s best to study only the first nine you randomly encounter before you choose. Examining fewer means you won’t have enough information to make a good choice, examining more makes it more likely you’ll pass the best mate by. No doubt, the models underestimate the complexity of real mate choice, but the fundamental insight is clear: Don’t search indefinitely before choosing, lest you miss out on all the good mates or run out of time altogether.

A sidebar to the article is here. (I must also say the professor looks very cute).

This does raise the question, which I have discussed with Tallman on occassion — do most of the best girls out there on the dating market get “snapped up” in their 20s? (I just look at this from a guy’s perspective of course, but I think women think along the same lines to some extent. I remember my friend M., whom I used to date, complain about her current boyfriend. Her exact words are lost to me but basically it was, “he’s 36 and never been married, that just goes to show something is wrong with him!” I was like, great, just three years before people will start saying the same thing about me…