I watched a program on PBS the other night about birds of paradise – exotic birds from New Guinea with elaborate displays. To attract females, males have evolved these intricate feathers and courtship dances and rituals. A Parotia male, for example, will clear out a dancing ground and when a female is in sight, he will puck up feathers around his chest into a sort of collar similar to those of Italian nobility of the Renaissance (or perhaps closer to a ballerina’s skirt) with bright iridescent feathers forming a shield below his neck, the long quills on his head that usually point lazily toward his rear will stick straight up in a semicircle around his head.
They can’t stop talking about her. “Look at how popular and successful she is!” “Look at how stupid and ditsy she is!” “What has she done to be so famous?” … Well, I don’t care if she’s smart or stupid, rich or poor. The only things I see when she’s on the screen are those voluptuous curves. Regardless of what you think of her, Kim Kardashian has what most men dream of. Since this is a nerds’ blog, we’re going to take the moment to examine why we men like those curves so much.
Men like women with large curves because these provide an adaptive advantage, increasing the likelihood of the propagation of genes. Wide hips are adaptive because they make child birthing easier (more successful); large breasts may provide more nutrition during nursing. The men who go for the curves are more likely to make successful offspring; those offspring incidentally share the same instinct for curves and eventually make more progeny; and the cycle continues. Now, Kim Kardashian is what you call a supernormal stimulus. She has everything that normally elicits a positive response but exaggerated. “Supernormal stimulus,” by the way, is attributed to the famous ethologist Niko Timbergen, who found that substituting a mamma-seagull’s white beak with its one red spot for a stick with three red spots made the chicks way more excited for food. Many more such examples have been described in a variety of animals.
But anyway, I am a male and my primitive brain can’t help but to love Kim Kardashian. One could say the male brain is predisposed or hard-wired to love curves like Kim’s. Actually, some folks are still amazed to hear that there are neural correlates of this or that (you see this in the news all the time – “scientists now found the brain mechanisms behind gambling,” social anxiety, or enhanced hearing in the blind. The list goes on). There won’t be any behavior, feeling, thought, etc without neural correlates. I dare you to show otherwise.
In an article on love and the brain, Psychology Today columnist Marnia Robinson describes the neural mechanisms that make prairie voles (similar to mice) pair bond, or stay as a couple for at least one round of mating). It has to do with the distribution of oxytocin receptors, which makes the vole associate its mate with the dopamine reward pathways, meaning that a couple stays together (“in love”) long enough to raise some pups. Marnia notes that we, like the voles, are “programmed to pair bond—just as we're programmed to add notches to our belts.” In another post in her column, she drives the point home:
“Pair bonding is not simply a learned behavior. If there weren't neural correlates behind this behavior, there would not be so much falling in love and pairing up across so many cultures. The pair-bonding urge is built-in and waiting to be activated… The vital point is that our pair bonding penchant arises from physiological events, not mere social conditioning… So, even though many Westerners appear to be caught up in a chaotic hook-up culture for the moment, it doesn't mean that we humans are, by nature, as promiscuous as bonobo chimps or that pair-bonding inclinations are superficial cultural constructs.”
What Marnia means is that committed relationships (perhaps marriage, too) are natural, and therefore you don’t have to worry that everyone you know is only interested in hooking up because they should prefer committed relationships; eventually they’ll all settle down and all will be right in the world. I hope you will forgive me for interpreting Marnia’s writing as a promotion of marriage and an attack on hook-up culture (after all, the title of her post is “Committed Relationship: Like It Or Not, You’re Wired For It”). Humans have a genetically-based neural system that enables them to fall in love and pair bond (again, it shouldn’t be surprising that we have a neural system for this; the only question is what roles do genes and environment play on it). But just because it is there doesn’t mean it is 100% deterministic.
It’s true, in some species the best strategy for gene propagation is for the couple to share the responsibility of child rearing. Evolution favors individuals with the monogamy instinct and it just so happens that monogamous relationships feel good to them. What Marnia is driving at is that you don’t have a choice but to end up in a committed relationship because your brain is “wired for it”.
Is that really true? Decision-making can be described as synaptic integration of relevant inputs based on their weights or importance. Unless you are a cocaine addict running on empty, the factors going into most decision have fairly weighted synaptic representation (i.e. a crack-head’s brain won’t allow factors other than crack to have a big vote in the decision-making congress). Just because a brain is predisposed toward some trait or behavior doesn’t mean that that trait is 100% deterministic. This idea of relative cognitive liberty here doesn’t even invoke free will; the decisions you make are based on the brain’s wiring, your previous experiences, probability, etc – not some soul that does what it wants.
And why does it matter that monogamy is the “natural” thing to do? Who cares what we are by nature? Last I checked, by nature dudes can be expected to throw themselves at every cake, cookie, jar of peanut butter and sexy lady they see. Haven’t witnessed that recently at the local Shaw’s… And it wouldn’t matter if “society” were “making” us do that – we control society! We choose what’s acceptable. If I want to sleep around instead of getting married, that’s my choice! (isn’t it ironic how it’s the conservative right that always worries about threats to personal freedoms and tries to deny personal freedoms in the name of traditional values?).
That doesn’t mean we can ignore our nature; we do have innate mechanisms that pull or push us in different directions – I don’t love Kim Kardashian because I chose to, but because as a man I have certain preferences built in. But here’s the catch: just because I think Kim is attractive doesn’t mean I’m going to ditch my girlfriend and hop on the next plane to Hollywood. I can control myself and stay in a meaningful relationship; I can inhibit this reptilian instinct. Likewise, not every man prefers Kim to someone with a flatter topology. We do have innate preferences, but they all have different impact on what we do or how we feel. Next time you see a headline about the genetic basis or experience-driven neuroplasticity of some trait or other, be wary: not everything is as intensely deterministic as the neuropundits will have you believe. For now stay content that you can enjoy Kim Kardashian’s curves without committing any social faux pas.