Q&A: Neuroscientist Larry Young on Sex, Drugs & Love Among Voles

He doesn't claim to have the answer for why fools fall in love, but psychiatrist Larry Young hopes studying prairie voles will help.

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He doesn’t claim to have the answer for why fools fall in love, but psychiatrist Larry Young hopes studying prairie voles will help.

The Emory University professor studies the differences between species of voles with very different sexual preferences: the montane voles are the serial daters and cheaters of their world, engaging primarily in promiscuous relationships, while prairie voles are more monogamous. By studying their brain chemistry, Young is hoping to expose the biology of fidelity and cheating, and the role that the so-called love hormone oxytocin plays in the way the voles make and break romantic relationships.  TIME talked with him about his new book, The Chemistry Between Us:  Love, Sex and the Science of Attraction.

As a scientist, why do you study love?

There’s really an important scientific reason for doing this and that is, if you can understand how we relate to each other, how these chemicals help us relate to others, we may be able to tap into that same chemistry to help people with autism and schizophrenia [and other disorders].

My research money doesn’t come to me because I am studying love. I used to totally avoid the word love. The real important lesson here is that by understanding this chemistry we can help facilitate the ability to engage with others.

Everyone likes to call oxytocin the “love hormone;” is that an accurate way to describe what the hormone does?

It makes such a good story.  They call it the hug drug, the love molecule and now [Claremont University neuro-economist] Paul Zak is even talking about the moral molecule. This is really a problem of the media trying to grab a short headline that people can grasp.

It’s not really the love hormone in [and of] itself.  It plays one role in a chemical cocktail and that role is to focus attention on others.  It increases the amount that you look into people’s eyes, for example.

[And] it’s not rewarding in [and of] itself.  If you think about a baby and mother interacting and it’s positive, both  release dopamine at the same time. The baby looks at the mother’s eyes. The mother smiles and the baby smiles and it’s the connection between the two  that creates the connections between [dopamine and oxytocin].

Love is a combination of the effects of oxytocin but also dopamine and the opioid system that gives pleasure: it’s a combination of all those things.

So that might be why people aren’t falling in love even when given oxytocin in lab experiments.  But what if you shoot heroin or cocaine while taking oxytocin with someone?

Yes, you might fall in love. We can inject dopamine and oxytocin to into animals and they form bonds so that suggests if that you combine oxytocin and cocaine, it could have similar effects.

Which came first: the monogamous connection facilitated by oxytocin, or the parental bond?

I think the maternal behavior part came first because if you look across mammals, nearly all mammals are not monogamous. But even if you go all the way back to earthworms, they have an oxytocin-like molecule involved in egg-laying behavior.

I think the molecule was first involved in the physiological process of birth. With mammals, you’ve got them needing to nurse and oxytocin is involved in milk ejection.  You also have to transform the mother’s brain so that she focuses her attention on the baby, so she becomes a mother.  Oxytocin is acting both on the body and the brain to transform her into a mother.

So, do you think pregnancy is as big a hormonal change as puberty?

I think it is.  I obviously haven’t experienced it myself but when I talk about this to groups of people, mothers really get it. They really felt a specific  change in focus of attention.  That baby is suddenly the most attractive thing in the world to them.

Virgin rats avoid pups. They’re annoying to them and will even try to bury them. But once she gives birth, a female rat will cross an electrified grid to get access to those pups.

And how do we know that oxytocin is involved in attachment to mates?

Our information for that comes from voles.  Meadow and prairie voles can all become mothers but what [monogamous prairie] voles have are additional  receptors for oxytocin in an area of the brain called the nucleus accumbens (NAC).  It’s involved in reward and reinforcement.

What oxytocin is doing in the brain is sharpening the focus and response to social stimuli. The NAC is also where dopamine acts to create and reinforce learning from experience.

The prairie voles have these convergences of dopamine and reward learning,  which create new synapses at the same time as you have input from social cues of the partner. That creates an association.

Is oxytocin involved in monogamous bonding for males?

I think it may play some role but vasopressin [a hormone released by the hypothalamus and also involved in constricting blood vessels] certainly plays a more prominent role.  It’s involved in territorial behavior and aggression.  And again what happens there is [in monogamous prairie voles], those receptors got shifted around and got to be expressed in abundance in an area called the ventral pallidum, right below the NAC. The NAC projects directly to it and it’s involved in the same processes, in learning and reward processes.  So again, it’s also involved in social information processing and memory.

Because those receptors are in that location, when neural signals come in and encode the cues of the partner— like odor— they converge on this reward learning place and they link [the partner] to that.

But this is also interesting. When males become monogamous, they don’t only just prefer to be with that partner, they also defend that partner.  It seems like that female becomes an extension of their territory and they engage in aggression towards others, even other females [when that female is threatened].

Don’t females also get more defensive to protect their young?

Females do get somewhat aggressive,  but that’s due to oxytocin.  Mothers do get aggressive if someone is threatening their baby. We do know that is linked to oxytocin in rats and mice and I guess probably in voles as well.  I think oxytocin has more of a nurturing kind of component [in females] because that’s what a mother has to do [while it makes] the male more vigilant: “this is my female, others better stay away.”

So how are love and addiction similar?

Our brains did not evolve to get addicted to drugs.  Drugs happen to act on a system that really evolved to help us get attached to things like other people, especially mothers and their unconditional love for their children.

Love is perfectly adaptive behavior, it’s a good thing— just because part of the brain uses a mechanism similar to addiction to get us to do things we [ordinarily wouldn’t do]  isn’t bad. The idea that they do use a common mechanism doesn’t mean that love is a bad thing or pathological at all. Biologically, there’s the added component of the social nature of love. You’re addicted, not to a substance directly stimulating your brain but to an individual who activates those same brain areas when you’re around.

(MORE: ‘Cuddle Chemical’ Oxytocin Relieves Alcohol Withdrawal)
What do you think of the idea of sex addiction?

I don’t really think there is sex addiction.  In some ways, we’re all addicted to sex because our brains are set up for us to want to engage in sexual activity, but I don’t think there’s such a thing as sex addiction. It’s certainly not a rationale for someone to [misbehave].  It’s not an excuse.

We all feel pleasure when we have sex, but we have parts of the brain like the prefrontal cortex that tell us when we should not engage in these kinds of behaviors.

So do you think infidelity is “normal” for humans?

It’s absolutely normal human behavior.  First of all, it happens a lot. Cheating is also adaptive if you can get away with it. Like Genghis Khan: if he had genes that made him the way he was— aggressive and dominant and wanting to have sex with as many women as possible— those genes got passed on to a lot of people.

Apparently, 1 in 200 men living today have some of his genes.  If they cheat, does it mean they aren’t to blame?

It never means that it’s not your fault.  Just because genes or a molecule modulate a behavior doesn’t mean that they determine that behavior. To me, the fact that a gene gives you twice as much probability that you’re going to cheat— that means that there’s a biological connection there. That gene influences behavior. If that means that 4% cheat versus 2% of people with a different variant, then that gene is not predicting the behavior at all.

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