This Is Your Brain on Sex (2 page)

Technology and science have now advanced to the point that disciplines like biology, genetics, epidemiology, evolutionary science, psychology, philosophy, computer science, and medicine have converged into the catchall field of neuroscience. More and more, neuroscientists are demonstrating that the brain
is
behavior—the two simply cannot be teased apart. Our brains are the seat of the biology that is directing every move we make. (I realize there are many who believe there is some kind of spiritual hand guiding our love lives, perhaps even influencing our brains. Given that it is a controversial argument that science can neither prove nor refute, I consider it outside the scope of these pages. But I will discuss some of the neuroscientific studies examining religious devotion and the brain in chapter 16.)

The latest neuroscientific discoveries provide a better understanding of the brain and its role in disease and behavior, including complex behaviors like attachment, romantic love, and sexual decision making. Researchers have now identified specific brain areas involved with love, different neurochemicals that may make us confuse love and lust, and genetic and environmental factors that may interact to change the way we approach our relationships. With these findings, the old-school debates about love framed in
nature-versus-nurture scaffolding (that we can simply
decide
to change the way we act, as many self-help and dating manuals claim) are being countered by a new perspective suggesting that we humans may be more enslaved by our biology than was previously thought.

Of course, it is not quite as simple as that. Current research also points to complex ways in which our DNA is directly influenced by our environment. Epigenetics, a blossoming new field in neurobiology, is demonstrating that environmental influences can actually alter gene expression during development and beyond. As technology advances to allow a more focused examination of this intricate dance between our brains and our environment, we can pose new questions about the nature of love—questions drawn solely from neuroscience, the science of modern human biology—and shed old assumptions based on self-help, sociology, and spirituality.

With innovative, cutting-edge methods like neuroimaging, genome-wide association studies, and transgenic animal models, scientists now have the ability to observe love-related phenomena at the molecular level. Forget person-to-person communication and its importance in relationships; we can now measure the communication between brain cells.

“We’re starting on a whole new world of research here,” says Helen Fisher, an evolutionary anthropologist at Rutgers University who studies love from a scientific perspective. She has even shared some of her insights on the brain and love as a consultant to the online dating company Chemistry.com. “It is just beginning—the brain scanning, the epigenetic studies, tracing the molecular signaling pathways involved with love. There’s so much here to help us answer the questions we’ve asked for centuries. We’ve only just begun to find out how love can turn off decision-making areas, how childhood may affect our emotional control, and for what kind of people love can become an addiction. Really, we’re just beginning to truly understand the nature of love from a neurobiological perspective. It’s tremendous.”

This is certainly a novel way to look at a universal, enigmatic phenomenon. Many of us hope that these studies can provide the answers we have always sought concerning love: What is it, exactly? How can I make it last? Is monogamy natural, or even possible? What is it about that person—that person who is so
not
right for me—that I find so utterly irresistible? Why has my love for my child changed the way I care about everything and everyone else? There are many perplexing issues to choose from, and because love also has the power to make most of us feel like utter fools, a few good answers would be welcome. But can the examination of hormones, neural pathways, and epigenetic regulation of genes really give us the answers to the desperate queries of our insecure hearts?

To date there have been thousands of scientific inquiries about the nature of love. There are probably just as many love-related advice books that have had their tenure on self-help shelves in bookstores across the globe. These days many
of those books (as well as the magazine articles and talk show themes based on them) claim to draw their advice from the newest neuroscientific evidence. They tell us that men and women have different kinds of brains and that we’re hardwired for specific love-related behaviors. They say certain chemicals (some available on the Internet for only $19.95 plus shipping and handling) can help us attract the right mate. They suggest that our biology dictates
everything
and that heredity plays a huge role in whether we will find success in love. What’s more, if we are willing to follow some simple guidelines based on the hottest brain research, we too can achieve relationship nirvana. The fact that the research findings cited in these books are often generalized, misinterpreted, or taken a wee bit out of context in order to promote a particular point of view does nothing to dampen their fans’ enthusiasm. It’s not such a surprise, really. These books tell us that if we follow the rules and approach our relationships in the “right” way, true love is within our reach. Some of these findings support ideas you may have had about love all along. Others seem wrong,
dead wrong,
in terms of both accuracy and appeal. They go against everything you were raised to believe about relationships. You read about those studies and find they have blown your mind (and heart) right out of the water, because if they are right, you are even more screwed than you thought: that true love thing is never going to happen for you. Headlines, guidelines, rules, lists, directions, and sound bites abound, but what can they really tell us about the nature of our hearts?

In fact neuroscientists offer no surefire way to avoid a broken heart or to make your marriage last. More often than not, they are far more interested in questions involving cognitive perception, consciousness, reward processing, or the behavior of previously uncharacterized genes. Some are looking at treatments for disorders like autism or cancer. The love stuff is important, yet somewhat tangential to the kinds of results scientists are really after.

Given the complex interplay between genes and environment in these behaviors (as well as the fact that most of these interactions are tested on animals and not people), any specific advice probably wouldn’t do you much good even if it were offered. Neuroscience, particularly epigenetic inquiries into the brain, suggests that although people’s brains have much in common,
they may be just different enough to require individual treatments for their myriad diseases. By extension, there may be some individual differences in the ways we approach love, lust, and relationships.

“Behavior is a really complicated thing,” says Alexander Ophir, a researcher at Oklahoma State University who studies mating and sexual behaviors in prairie voles, a breed of small rodent that forms the foundation of most monogamy research. “There are major differences between us and the voles. We humans have consciousness and culture that affect our behaviors. Taken all together, those things make the study of these behaviors quite messy.”

More and more it is looking as if there is no one-size-fits-all approach to successful relationships. If we can, indeed, “blame biology,” we can look only as far as our own. This idea is terrifying but liberating. Our complicated behaviors make for complicated minds—I’d even go so far as to say “dirty” minds, with so many variables muddying the proverbial waters—and make for complex study.

The following pages will provide no advice or guidelines regarding love. This book will not tell you how to become more attractive to the opposite (or same) sex, how to become a better parent, or even how to make your mate stay with you. And though I may want to tell you to drop the hot new relationship book, throw out those brain chemistry supplements you bought, or change the channel when Dr. So-and-So’s syndicated advice show airs, I’ll refrain.

What I will do is try to explain what neuroscience has actually learned about the various ways our brains can affect our hearts—and what those findings mean within the context of human behavior. Even without the inclusion of five steps to staying faithful or ten ways Mom can benefit from Dad’s biological parenting style, it may put what you are reading or watching on television into the right context. I hope it will steer you away from picking up a pill or spray (or, if not, at least give you a better idea of what such a concoction might actually do). If nothing else, I hope to offer you a better understanding of why we humans act so strangely when it comes to that crazy little thing called love.

Chapter 1

The Neuroscience of Love: A History

(Theirs and Mine)

In 1994 a scientist named
Sue Carter submitted a grant application to study a hormone called oxytocin (not to be confused with the narcotic Oxycontin, aka hillbilly heroin) in a small rodent called the prairie vole.

A prairie vole family.
Photo by Todd Ahern, University of Massachusetts.

A prairie vole (
Microtus ochrogaster
) looks a lot like your garden-variety mouse, but scruffier and with a shorter tail. Happily burrowing under gardens and meadows in a large stretch of central North America, these small rodents might completely escape our notice except for one special trait: they are monogamous.

Socially monogamous, that is. Unlike most other rodents—or most other mammals, for that matter—prairie voles form lifelong pair-bonds, or lasting social and sexual
relationships with a single member of the opposite sex. Both males and females are also directly involved with the parenting of offspring. Because of the rarity of such habits in the animal kingdom, many animal behaviorists have become exceptionally interested in the prairie vole. One such researcher was Carter.

A professor of psychiatry at the University of Illinois at Chicago, Carter hypothesized that oxytocin, which is linked to childbirth and breastfeeding, could increase social attachment. She had already conducted research to support the idea and hoped that this grant would allow her to continue studying the hormone and its relationship to social behaviors in the prairie vole. In her application she did not mention love, marriage, or even humans. Somehow the grant review committee decided she was studying the little four-letter-word that begins with an
l
—love, that is—which was considered a serious no-no in the hard science climate of the day.

“I was trying to get federal grant funding to continue my work, and suddenly I was accused of studying
love,
” she said when I visited her lab in Chicago. Petite, white-haired, and a little bohemian in style, Carter somehow managed the feat of being both incredibly welcoming and intellectually intimidating at the same time. “Honestly, it was a shock to me. I would not have used the word
love
—I never used the word
love.
I didn’t think about the work in terms of love. I was simply talking about a preference of one animal for another—not some human construct that seemed to have little to do with what we were actually studying.”

Carter told me she was unsure of how to respond to the review. She conferred with Kerstin Uvnäs-Moberg, a fellow scientist also interested in oxytocin who was working at Stockholm’s Karolinska Institute. Could it be that their work was related to something as messy and indefinable as love? Might there be a neurobiological basis for the future study of love? Looking at newly published research by various labs concerning oxytocin, social attachment, and pair-bonding in prairie voles and other mammal species, the answer seemed to be yes. Carter and Uvnäs-Moberg thought it was time to stop ducking the topic and admit that their work did have implications for human behavior.

“It seemed like the time to really try to articulate and explain the idea that social bonds were critical to human love,” Carter said. While sex was, is, and will be of the
utmost importance to propagating our species, Carter and Uvnäs-Moberg were convinced that love needed to be articulated in the context not only of genetic propagation but also of survival—specifically, the ways social bonds can help people thrive in the face of stress and other complexities of life on a daily basis. Perhaps our brains promote social relationships in order to ensure that more than one person is on tap to avoid dangers, to make sure there is enough food around to feed the family, and to help raise the young’uns. Investigating how the neuroscience underlying social bonds might promote these behaviors seemed a pertinent line of study.