The Science of Love
Losing our faculties over a matter like love ought not to make much sense for a species like ours that relies on its wit. The lure of losing our faculties is one of the things that makes love thrilling. There's the transcendent sense of tenderness you feel toward a person who sparks your interest. There's the sublime feeling of relief and reward when that interest is returned. Human beings make a terrible fuss about a lot of things but none more than romance. People compose poetry, novels, sitcoms for love. They live for love, die for love, kill for love. It can be stronger than the drive to stay alive.
On its good days (and there a lot of them), all seems to make perfect sense. What scientist, not to mention the rest of us, want to know is, Why? What makes us go loony over love? We have only a very limited understanding of what romance is in a scientific sense. But our limited understanding is expanding. The more scientist look the more they are able to tease romance apart into its individual strands - the visual - the auditory, olfactory, tactile, neurochemical process that makes it possible. None of those things may be simple for simple procreation, but all of them appear for something larger. What that something is - and how we achieve it - is only now coming clear.
One of the most primal of those desire is that the possible partner smells right. Good smells and bad smells are fundamentally no different from each other. Both are merely volatile molecules wafting off of an object and providing clue to the thing that emitted them. Humans, like all animals, quickly learn to assign values to those scents, recognizing that, say, petrifying flesh can carry disease and thus recoil from its smell and that warm cookies carry the promise of vanilla, sugar and butter and thus being drawn to them. Other humans carry telltale smells of their own, and those can affect us in equally powerful ways.
Precise as the MHC is, it can be confounded. One thing that throws us off the scent is the birth-control pill. Women who are on the pill - which chemically stimulates pregnancy. When they discontinue the daily hormone dose, the protective smell mechanism kicks back in. One has to wonder if this may contribute to divorce. Women pick a husband when they're on birth control, and then quit to have a baby and realize they've made a mistake. Kissing serves the utilitarian purpose of providing a sample MHC, but it also magnifies the other attraction signals - if only as a result of proximity. Scent is amplified up close, as are sounds and breaths and other cues. And no one of that begins to touch the tactile experience that was entirely lacking until intimate contact was made. At the moment of a kiss there is a rich exchange and complicated exchange of postural, physical and chemical information. There are hardwired mechanisms that process all of this. Though testosterone is found in a higher concentrations in men than in women, it is present in both genders and is critical in maintaining arousal states. Traces of testosterone make it into men's saliva, particularly in men that have high blood levels of the hormone to start with, and it's possible that a lot of kissing over a long period may be a way to pass some of that natural aphrodisiac to the women, increasing her arousal and making her more receptive to even greater intimacy.
The elaborate ritual of dating is how this screening takes place. It's when that process pays off - when you finally feel you've found the right person - that the true-love thrill hits, and studies of the brain with functional magnetic resonance images (fmris) show why it feels so good. The earliest fmris of brains in love were taken in 2000, and they revealed that the sensation of romance is process in these three areas. the first is the ventral segmental, a clump of tissue in the brain's lower regions, which is the body's central refinery for dopamine. Dopamine does a lot of jobs, but the thing we notice most is that it regulates reward. When you win a hand of poker, it's a dopamine jolt that's responsible for the thrill that follows. When you look forward to a big meal or expect a raise, it's a steady flow of dopamine that makes the anticipation such a pleasure.
Recent fmri scans of people who are not just in love but newly in love and have found that their ventral segmental areas are working particularly hard. This little factory near the base of the brain is sending dopamine to higher regions. It creates craving, motivation, goal-oriented behavior - and ecstasy.
Even with its intoxicating supply of dopamine, the ventral segmental couldn't do the job on its own. Something has to turn the exhilaration's of a new partner into what can approach an obsession, and that something is the brains nucleus accumbens, located slightly higher and farther than the ventral segmental. Thrill signals that start in the lower brain are processed in the nucleus accumbens via not just dopamine but also seratonin and, importantly, oxytocin.
The last major love signals in the brain are the caudate nuclei, a pair of structures on either side of the head, each about the size of a shrimp. It's here that the patterns and mundane habits, such as driving and knowing how to drive a car, are stored. Motor-skills like those can be hard to lose, thanks to the caudate nuclei's inedible memory. Apply the same permanence to love, and it's no wonder that early passion can gel so quickly into enduring commitment. The idea that even one primal part of the brain is involved in processing love would be enough to make the feeling powerful. The fact that three are at work makes that powerful feeling consuming.
The problem with romance is that it doesn't always deliver the goods. For all the joy it promises, it can also play us for fools, particularly when it convinces us that we've found the right person, only to expend our expectations later. Birth-control pills that mask a woman's ability to detect her mates incompatibility MHC are one way bad love can slip past our perimeters.
If that sounds a lot like what happens when people meet and date under regular influence of drugs or alcohol, only to sober up later and wonder what in-the world they were thinking, that's because in both cases powerful chemistry is running the show. When hormones and natural opioid get activated, you start drawing connections to the person who was present when those good feelings were created. You think it's someone that made you feel good but it's really your brain that made you feel good.
Of course, eventually a love-fever that's healthily shared breaks eventually, in only because - like any fever - it's unsustainable over time. The dangers of maladaptive love in fmri, studied, shows that people that have been rejected by a lover and can't shake the pain, as with all people in love, there is activity in the caudate nucleus, but it's specifically in a part that's adjacent to a brain region associated with addiction. If the two areas indeed overlap, it helps explain why telling a jilted lover that it's time to move on can be fruitless - fruitless as instructing a drunk to put a cork in the bottle.
Nature doesn't really care if we experience the thrill of falling in love or not. Companion-ate love bonds us to our partner. The eventual goal of any couple is to pass beyond serial dating - beyond even the thrill of early love - and into what's know as companion-ate love. That's the coffee-and-Sunday-paper phase, the board-games-when-it's-raining phase, and the fact is, there's not a lick of excitement about it. But that, for better or worse, is adaptive too. If partners are going to stay together they need a love that bonds them to each other but without the passion that would be a distraction. As early humans relied more on their brainpower to survive - and the dependency period of babies lengthened to allow for the necessary learning - companion-ate bonding probably became more pronounced.
That's not to say that people cannot stay in love or that those couples that say they still feel romantic after years of being together are imagining things. Some of those suborning loving pairs, and initial results show that their brains indeed look very much like those of people newly in love, with all the right regions lighting up in all the right ways. It really does happen. These people, however, are the exceptions, and nearly all relationships must settle and cool. That's a hard-truth but it's a comforting one too. Long for the heat of early love if you want, but you'd have to pay for it with the solidity you've built over the years. You've got to make a transition to a stabler state. If love can be made to be made mundane that's because sometimes it's meant to be.
Calling something like love mundane, of course, is true only as far as it goes. survival of a species is a ruthless and a reductionist matter, but if staying alive if truly what it were all about, might we not arrived at it in ways to do it without joy - as we could have developed language without literature, rhythm without song, movement without dance? Romance may be nothing more than reproductive filigree, a bit of decoration that makes us want to perpetuate the species and make sure we do it right. But nothing could convince a person in love that there isn't something more at work - and the fact is, none of us would want to be convinced. That's a nut science may never fully crack.
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