Skip to main content
Live Well

Casual Sex is Never Casual: What the Brain Reveals

09 May, 2019 | Posted by Kate Green Tripp

Find More Readings

Casual Sex is Never Casual: What the Brain Reveals
Dr. Helen Fisher is an internationally renowned neuroscientist, biological anthropologist, and pioneer in the biology of human personality. Named one of "the 15 most amazing women in science today" by Business Insider, Dr. Fisher is the most referenced scholar in the field of love and relationships in the world today. She is a senior research fellow at the Kinsey Institute, an anthropologist at Rutgers University, and chief scientific advisor for

1440: Let's talk about what neuroscience reveals about love. What happens in the brain when we are in love?

Helen: I'd like to first define love. I'm a neuroscientist, and I think we've evolved three distinctly different brain systems for mating and reproduction.
One is the sex drive. The second is feelings of intense romantic love. And the third is feelings of deep attachment. It's important to consider that all three are connected, though not always. You can fall madly in love with one person and feel deeply attached to another.

1440: Let's talk about romantic love.

Helen: My colleagues and I have put over 100 people who were madly in love into a brain scanner.
The first group were people who considered themselves happily in love. The second group were people who had just been dumped, or rejected in love. And the third were people in love long-term—people married an average of 21 years who said they were still in love.
Among those who were happily in love, we found the greatest brain activity in a tiny little factory near the base of the brain called the ventral tegmental area (VTA). It is a brain region that makes dopamine, which is a natural stimulant.
Dopamine gives you optimism, focus, motivation, energy, and can also give you intense feelings of romantic passion.
What's interesting about the VTA is that it lies in the same general region as the brain factories that orchestrate thirst and hunger. So, it occurred to me, wow, being in love is not an emotion. There's a lot of emotions involved in romance, of course. There's a lot of cognitive thinking processes involved too.
But, basically, romantic love is a drive—a primitive drive that leads us to seek life's greatest prize: a mating partner.
So, that's why we (myself and my brain scanning colleague Lucy Brown) call it a "survival mechanism." Romantic love evolved in the brain as a basic reproductive tool to drive you to form the kind of relationship that may lead to children and enable your DNA to survive into the next generation.

1440: What did you learn from studying the brains of people rejected in love?

Helen: For me, it was even more important to understand the neural pathways of rejection than what happens in the brains of those happily in love. As expected, we discovered activity in the same brain region—the ventral tegmental area way down in the drive region of the brain.
This makes sense because you don't stop loving somebody when you have been rejected. In fact, you can love them even harder. I call it "frustration attraction."
When there's a real barrier to relationship, this brain system can work even harder.
But we also found activity in a brain region linked with feelings of deep attachment to the partner. Attachment also doesn't die when you are dumped. And we found activity in three brain regions linked with craving and addiction.
That's what I was looking for.
There's a brain region called the nucleus accumbens that becomes very active when you have any substance addiction, like alcohol or nicotine or cocaine. But the nucleus accumbens is also activated during all behavioral addictions—everything from gambling to sex addiction to eating disorders to kleptomania. And this same brain region that becomes active in all of the substance and behavioral addictions also becomes active when you are rejected in love.
Radiant Intimacy
Helen Fisher, PhD,  Terry Real,  Diane Poole Heller, PhD,  Michaela Boehm,  Steve James,  Celeste Hirschman, MA,  Dimitry Yakoushkin,  Zaya and Maurizio Benazzo
May 24 - 27, 2019
We all long for love. We long to be intimately connected to ourselves and others. For some, a partnership or marriage is the natural outcome of this longing. Others find alternative styles of intimacy more fulfilling. For most of us,...
Learn More
That discovery drove me to go back and look at people who were happily in love to see if they were activating this region, and indeed they were. I can't get another person in my field to believe me, but I think that romantic love is a positive addiction when it's the right person at the right time and all is well. It is a positive addiction that evolved millions of years ago to drive us to form a pair bond and send our DNA into tomorrow.
But, it can certainly be a horribly negative addiction also.
Simply put, I think it's an addiction and it needs to be treated as an addiction. It's amazing how many therapists will say, "Well, just leave him (or her)." And yet, you can't just leave the person if it's an addiction. You have to know how to handle it.

1440: How do you believe rejection is best handled?

Helen: I think the Alcoholics Anonymous (AA) philosophy applies: Get rid of the cards and letters. If you can't get rid of them, put them in a closet where you can't see them.
Don't write. Don't call. Don't show up. Don't ask your friends about the person.
What you're doing when you do any of those things is just reviving the ghost. There's somebody living in your head, and you've got to get them out. If you drunk call them on New Year's Eve and they're nice to you because they feel guilty and it spurs your hope again, you're just waylaying the process of recovery.
When studying people rejected in love, we also saw activity in a brain region in the anterior insula that is linked with anxiety, stress, and physical pain.
This particular brain region becomes active when you have a bad toothache.
The difference between romantic rejection and a toothache is you go to the dentist, you solve the tooth problem, and a week later you've forgotten it. But it can take months or years of trying to get over a rejection in love.

1440: Do you believe we can move from being in love with someone to being friends?

Helen: I think it is a myth to think we can transition from one to the other. One of the things I say to people after a breakup is, "Tell the person: Look, I have to get over this. I'll get back to you in two or three years when I'm completely over it."
Then, two or three years later, you've lost that passion. You haven't forgotten, of course—the memory system doesn't get killed—but the emotions that go along with the rejection are now gone, and you have moved on.
We have proven with our brain scanning that time heals.

1440: What does neuroscience reveal about sex? You say there is no such thing as casual sex. What does that mean?

Helen: Unless you're so drunk that you can't remember it, there's no such thing as casual sex because the brain is always responding.
Sex triggers 5 of the 12 cranial nerves.
At the same time as you are physically stimulated, the brain is ticking along collecting data: Is this person kind? Are they patient? Are they humorous? Can they listen to what I need?
When you are having sex with somebody, it heightens all of your basic senses: You can really see them. You can really hear them. You can really feel them. You can really taste them. You can really touch them.
I do an annual study called Singles in America. We poll a national representative sample based on the U.S. census. And recently I asked the question, "Have you ever had sex with somebody before the first date?" Thirty-four percent of singles said yes.
So, what are they doing?
I think they're collecting data in what amounts to a sex interview.
It seems crazy to say, but I actually think this stems from caution. Today's singles want to know a lot about a potential partner before they invest their time, their energy, and their money in an official first date.  In short, I think we're beginning to see an extension of the pre-commitment stage of partnerships.  I call it "slow love."
We live in an age where most Americans are not scared of getting pregnant. They know how to handle that. They're not scared of disease. They know how to avoid that. They don't have to walk the walk of shame. So, the lid is off the pot, and people are having "casual" sex (which is not casual at all) to collect data about whether they want to seriously invest in this person.
Kate Green Tripp is the Managing Editor of 1440 Multiversity.

Stay Informed

Sign up and receive insider offers and flash sales in your inbox every week