This Is Your Brain on Sex (39 page)

The view of love as an emergent property of a cocktail of ancient neuropeptides and neurotransmitters raises important issues for society. For one thing, drugs that manipulate brain systems at whim to enhance or diminish our love for another may not be far away. . . . Perhaps genetic tests for the suitability of potential partners will one day become available, the results of which could accompany, and even override, our gut instincts in selecting the perfect partner. Either way, recent advances in the biology of pair bonding mean it won’t be long before an unscrupulous suitor could slip a pharmaceutical “love potion” in our drink. And if they did, would we care? After all, love is insanity.
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The essay generated a lot of talk, both in the neuroscience world and beyond. Some argued that Young had overreached, that even if the neurobiology had advanced to the point where we could create a so-called love potion (most agreed it had not), it was unethical, and perhaps even dangerous, to do so. Others, such as the
New York Times
writer John Tierney, cheered in anticipation
of “an anti-love potion, a vaccine preventing you from making an infatuated ass of yourself,” that was supposedly on its way.
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When I visited Young and his lab full of loving prairie voles in Atlanta, I asked him about the essay. “Do you think a love drug or some kind of genetic test for love is something we actually could do at this point? More important, is it something we should do?”

“Should we? I don’t think it’s something we should go toward. No, I don’t,” he replied. “And it’s not something we could do now, for sure. Given all this great work, the molecular and the behavioral and the genetic studies, we might be able to one day do these things.” He paused for a moment. “But it would be a shame if we made a decision about another person based on a genetic test or some drug rather than our gut reaction. We could miss out on someone great.”

In fact the neuroscientists I spoke with unanimously agreed that the creation of a Love Potion No. 9 based on the neurobiological study of love was a bad idea. Not only do we not yet know enough to create a drug that would work as intended, but, if we ever did get there, the risks involved in making changes to such an evolutionarily preserved brain system are immense. What about that love vaccine? You know, for those of us who want to avoid love and its myriad messy symptoms, like distraction, obsession, and even pain. Certainly the creation of a vaccine seems more benign than that of a love drug.

“That idea struck a chord with a lot of people. There are a lot of people walking around who just can’t get someone off their mind,” Young said. “I got a lot of letters about that one. In fact I got three handwritten letters from a man in Kenya. He read the
New York Times
article and wrote asking, ‘Please, can you send me this vaccine for love? I need it.’ He sent one letter every three months begging me for this vaccine.”

I imagine the gentleman from Kenya is not the only one. Many of us who have felt love’s keen sting may be just as desirous of a drug or a vaccine. If nothing else, I believe most of us are craving a few answers. Just a few biological clues, perhaps, about how we might better traverse love’s muddy waters in a way that will allow us to open yet protect our delicate hearts.

If this were a self-help book, this is where I would tell you that I fell madly in love during
the course of my research—that the things I learned as I explored the neurobiology of love, sex, and relationships helped me to finally track down my soul mate. Perhaps some hot neuroscientist who just knew we had matching oxytocin levels as soon as he strapped my head down for fMRI scanning. Or a successful doctor who just so happens to be my optimal major histocompatibility complex match as well as a guy with the right kind of
AVPR1A
variant for a loving and stable relationship. Perhaps I didn’t even need to find someone new. Maybe my research into love helped me to better understand how my “dirty mind,” or my unique epigenetic backdrop, played a role in the unraveling of my marriage. And with that understanding, my ex-husband and I are on our way to reconciliation, a neurobiologically based happily ever after. It would be a great clincher for a memoir or a cheesy made-for-TV movie.

Of course, none of that happened. That’s just not how science—at least real science—works.

New research is revealing some truly remarkable stuff. We’re learning a lot about how a variety of neurochemicals work together to make physical changes to our brains and about how our environment is involved in those changes. But the exact in’s and out’s remain an enigma, a puzzle yet to be solved.

“I think it’s amazing that things that we never considered to be biologically based or chemically driven, like love, desire, and attachment, really are just that,” Young told me. “There is a cascade of neurochemical events happening in the brain that cause us to feel the way we feel about another person and behave the way we do when we feel them. Sure, we have this cortex that allows us to think about things and to plan things—but underneath we have these ancient neurochemical systems that influence states we’ve long considered to be uniquely human. That’s a big deal.”

We’re only beginning to understand that. Though there are some truly amazing findings in the literature, there aren’t any that can be summed up in “Five Ways to Make Love Stay” or “Why His Brain Makes Him Cheat.” Why not, you ask? The science published to date can offer you four very important reasons.

Because our brains are plastic
. When I participated in the decision-making study at Indiana University,
I did not find any of the young Abercrombie & Fitchesque boys all that attractive. At least, not attractive enough to want to say I’d go to bed with any of them. When I lamented about my lack of interest in those young, stupid-haired boys to Julia Heiman at the Kinsey Institute, she smiled and simply said, “I don’t think how you are today is how you’ll be forever.”

She’s right. Our brains are always changing. As our neurobiological insight into the brain grows, we’re learning that it is incredibly plastic; that is, it is changing throughout our lives. With every new experience, every new item learned, every new relationship, there are subtle changes to our synapses. Over time those little changes add up to quite a lot. The brain I had when I first fell in love as a teenager is not the same one I have now. Neuroscientists are still working hard to suss out the details of that incredible plasticity, and they have a long way to go. But it is now clear that our brain is not a static thing.

“Plasticity is a funny thing,” said Thomas James, the Indiana University professor who led the appetitive decision-making study. “It used to be thought that our brains were done growing around six years of age. That was it, they were done. And we’re only starting to understand all the ways the brain remains plastic your entire life. That has huge implications for all of neuroscience research.”

That includes the study of love. How I respond—how the chemicals in my brain respond—to a member of the opposite sex may very well change as I age. Not to mention after more extreme alterations to my brain and body that were brought on by pregnancy and childbirth. How it all changed, and how it will influence my neurochemistry and complex social behaviors both now and in the future, is just not well understood yet.

In the future, as more of the neuroscience community branches out and studies populations outside those easily recruited on the university campus, it’s likely we’ll see that this plasticity matters—and matters a lot—when it comes to complex social behaviors like love and monogamy.

Because our brains are complex.
Neuroimaging studies have shown us that love has its own unique pattern of activation in the brain. But as Stephanie Ortigue, the neuroscientist from Syracuse University, reminded me, that pattern does not tell us the
whole story. Neuroimaging measurement is currently limited by both speed and detail; as the technology evolves, we will learn more about how the neuroanatomical pieces of the love puzzle really fit together.

When I asked Craig Ferris, the aggression researcher who also happens to be an expert in neuroimaging, to describe the challenges of drawing conclusions from fMRI studies examining complex behaviors, he told me that current techniques lack the detail necessary to understand what the brain is really doing during any complex behavior. He used the amygdala, a brain area implicated in many love-related studies, as an example. “The rat has approximately twenty different subdivisions of the amygdala,” he said. “People have spent lifetimes mapping just the amygdala in the rat, to understand the complexity of all these different subdivisions, what they do and what they project to. Each one of them does something different. It’s a pretty complex little area. When you look at human neuroimaging work, however, you only see two parts of the amygdala mentioned: the left and the right. It’s just a tough place to image in humans, so we’re limited to that. But it begs the question, what does ‘amygdala activation’ really mean in these studies? Until we can get to a certain level of detail, to map out all the different parts of the amygdala in humans, I don’t think we can really say that we know.”

These measurements are a lot less explicit than we’ve been led to believe. Amygdala activation has been linked to understanding social cues as well as adding emotional valence to the outside world. It could, however, do much, much more. It likely plays a subtle role in a variety of other cognitive processes. As time moves on and with better technology, we will discover the extent of its function.

Beyond the tricky interpretation of neuroimaging studies, our understanding of the way different neurochemicals work when it comes to love is also limited by complexity. Oxytocin, dopamine, vasopressin, estrogen, testosterone—these are all chemicals that have been implicated in love and sexual behaviors. They are also the candidates for the love drugs and vaccines that many hope will soon be on the market. There’s only one problem: they interact and cross-talk in ways that neuroscientists have yet to fully understand. They can lock up with one another’s receptors. They can influence each other’s production. And they are involved with many more bodily processes than just plain old love and sex.

When I asked Sue Carter, one of the pioneers in oxytocin and pair-bonding research, about the possibility of a love or a monogamy drug, she responded with some concern. “If we were to take what we already know about all the other biological systems, we’d immediately think twice about trying to fool Mother Nature with a drug,” she explained. “Love is important. We need to be very careful. The chronic use of a drug meant to affect the oxytocin receptors, for example, has all kinds of interesting potentials that, as far as I know, have not been properly studied in any model. It is possible that there will be a down-regulation in the production of endogenous oxytocin. Over time the brain and the body might stop making the natural hormone. The second concern would be that the production of the oxytocin receptor might down-regulate. This would create a less reactive system. You would need more and more of the drug to get the same or maybe even lesser effects.”

Until neuroscientists can better elucidate the how’s and why’s of the many ways these chemicals operate in the brain and the body, it’s chancy to even consider taking a drug or vaccine. That includes snorting a little oxytocin spray, spraying yourself with some androstenone, or taking a so-called love-related brain chemistry supplement—all already available for sale on the Internet. “We just don’t know what will happen if you interfere with the natural feedback loops, and so far this has not been properly studied even in an animal model,” Carter said.

More important, simply upping one type of chemical is not going to give you the effect you want. It flies in the face of the fact that humans are much more than the sum of their neuropeptides. We need all of these chemicals—and a whole lot more—to experience love. “Biology is only a part of love. There is your culture, there is your background, and there’s your huge cerebral cortex that can reason you out of it in the right circumstances,” said Helen Fisher. “We are in the infancy of this field. We are only beginning to understand all the ways the brain may be involved with love. We are only beginning to understand just how complex it all is. It’s going to take a lot of time to get to the bottom of it.”

Because context matters.
Our brains do not act in a vacuum. They are profoundly affected
by our environment—right down to the neuron. As Moshe Szyf, the leading epigeneticist, said, “You can’t just study the cell anymore. There isn’t just a cell.” All of our behaviors, including love and sex, can be understood only within the context of our environment. In fact at the level of our genes, those behaviors are actually regulated by our environment.

“The genome is set at a certain level. That’s highly programmed, certainly,” said Szyf. “But the early life environment sends signals to the genome saying, ‘This is the kind of world this kid is going to live in. Let’s program all these things to fit in with this world.’ And then it resets the system. It makes very small changes in many, many different genes so the animal can adapt to the outside world.”

And, as demonstrated by Szyf’s and Michael Meaney’s work, these include changes that have the power to alter our parenting and reproductive behavior. Blaming biology, as it were, for our relationship foibles does not cover it. Our environment and our relationships with others play an equally important role.

Because we are all individuals.
This is the big one. Plasticity, complexity, and context all come together to make sure that each of us is unique in our own way. We’re the product of our genes and our experiences. Don’t think the sum of all that is not going to have some bearing on our love lives.

“The truth about sexuality, about love, about complex behavior in general, is that it is incredibly variable,” said Julia Heiman. “So much so that many people say variability is the norm. And, you know, that fits in well with biology. Variability and biology go hand in hand.”