A couple weeks ago an article in The Economist made the claim that love is just a chemical addiction. That's not quite all that it went on to say, however. While this looks bad for true romantics, the conclusions those who read the whole article will find will show something much more in favor of some thoughts I've long had and that I think Christians should be excited to see scientific support for.
Prairie voles release oxytocin and vasopressin during sex. Scientists have discovered that blocking this release leads to promiscuity among voles, but otherwise they mate for life. These hormones have something to do with their monogamy. Montane voles, on the other hand, do not release these hormones during sex and do not mate for life. When artificially stimulated with these hormones on the occasion of sex, they still do not mate for life. They don't have receptors in their brains for these hormones. Other than that difference, these voles are pretty much genetically the same. That means monogamy in higher animals is not a result of more complex brains or higher-order thought processes. It's a result of the ability to receive these hormones and only that ability. (They even did genetic manipulation on these voles to give the montane voles the gene for the receptors, and that did the trick, whereas removing it from prairie voles removed their ability to form a monogamous bond).
That's the bad news for romantics. We already know that animals in general continue to eat, drink, and have sex because it feels good. These activities produce dopamine in the brain. What people have often thought is that such animal desires can be sublimated by higher emotions like romantic love or higher thought processes like rationally belief formation (e.g. knowledge that unprotected sex can lead to disease or unwanted pregnancy). This research finds a chemical basis for at least the stuff we have called romantic love. The vasopressin and oxytocin lead to an association between sex and a particular partner. For mice this association is with the smell of the mate. There's an olfactory "image" (so to speak -- think Daredevil) of the mouse's partner, and that image is associated with intense pleasure.
Humans also release oxytocin and vasopressin during sex. A study in the UK linked higher levels of these hormones in brains of students who said they were madly in love. There are similar hormonal differences involving friendship, however, and this involved a much larger area of the brain. Also, the hormones associated with what these students were calling love was focused on the part of the brain that we already know has to do with gut intuitions and narcotics. Other strong emotions involve different parts of the brain.
A closer look shows three levels of what broadly might be called love: lust, romantic love, and long-term attachment. (In my terms, these would be lust, romantic infatuation, and love. I don't see the second kind as really love, though it's often blindly called that by younger people who have never experienced love.) Lust is a craving for sex, and lustful sex leads to a brain state similar to an opium high. Infatuation has "feelings of exhilaration, and intrusive, obsessive thoughts about the object of one's affection." This is commonly called "being in love" in high school and even in college. The brain state here doesn't resemble an opium high but is more like the more permanent brain states of someone with Obsessive-Compulsive Disorder. Finally, there's what I would say is love, a permanent attachment. The brain state here is similar to what's associated with "feelings of calm, security, social comfort and emotional union." The emphasis of the study on hormonal changes in the brain is followed by a warning not to ignore cultural and social factors, which play a big role in bringing on those changes.
What does this mean? If certainly confirms the age-old wisdom that teenage "love" is not the same thing as love. The relative independence of these three levels of hormone change explains why so many people who base their relationships on teenage puppy love will fall "out of love". What most likely has happened is that they never fully reached the third stage or at least couldn't maintain it. They have perceived their love as the presence of the obsessive-compulsive features of the second stage, and when that has disappeared they assume there's no more room for love. It also explains why so many people can experience lust for someone other than the person they've bonded with for life without it interfering with that love (at least in any noticeable enough ways to stop them). The parts of the brain and hormones involved are relatively independent.
What struck me most about this, though, was that it seems to confirm something I've long believed about sex. Even someone's first sexual encounter forms some sort of bond. It's not the case that this is biologically the type of bond that causes bonding for life, but that sort of bond is already in the process with the first sexual interaction between two people. The mental link between the relevant hormones and that person are already in place, and there seems to be a natural process to try to keep it in place. Somehow some of the other higher functions of human beings can interfere with it, in a way that prairie dogs can't do, since one sexual act creates a permanent bond between these animals. That doesn't always happen with humans, but I'm wondering whether this is scientific evidence that it should.
If so, then what's different about humans to prevent it from happening? Biologically speaking, they may not know, but that's for empirical science to discover. A Christian can certainly see whatever it is as a consequence of the fall. So the romantic may be threatened by this research, but in the end it's quite friendly to Christian views about sex and love.