Over the past decade, neurobiologist Jim Pfaus has spent far too many hours watching rats “copulate”—or as we say at Playboy, “fuck.” As a professor at Montreal’s Center for Studies in Behavioral Neurobiology at Concordia University, he’s dedicated his career to researching how brain systems influence sexual arousal, desire, reward, and inhibition in laboratory animals, asking the question whenever possible, what does rat sex tell about human sex?

It turns out quite a bit. At the Society for the Scientific Study of Sex (SSSS) 2014 conference in Omaha, this November, I listened to Pfaus distill years of lab-rat research into a gripping, keynote speech. His approach is talk-show host funny, the Bill Nye of sex, but with more subversive attitude. In a room full of sexperts focused on literally every aspect of human sexuality (from pedofilia and late-in-life orgasms to the sexualities of people recovering from surgeries and the healthcare needs of the BDSM community) every ear perked up as he walked us through the ways that human sexuality and animal sexuality are really not that different. Not only do humans freak like animals (there’s a reason we call it doggie style), but we actually process sexual experience in neurologically similar ways to other animals. We have some of the same sexual wiring, dating back 650 million years. So much of our courtship insanity is far from new.

Before the conference ended, I sat down with Pfaus in hopes of fine-tuning my own understanding of sex and the brain. Pfaus ended up schooling me on why alcohol doesn’t always free us from sexual inhibition, why really good sex can make us feel like we’re in love, and why we all want our sexual partners to objectify us.

As it turns out, he’s hardly afraid to say fuck.

PLAYBOY: What has your lab attempted to figure out about the relationship between sex and the brain?

PFAUS: You know, Woody Allen thought his brain was his favorite sex organ, but your brain is your sex organ. The rest of our body is just kind of… the works. We can think of sex as encompassing four categories—arousal, desire, pleasure, and inhibition. It’s the brain that is creating arousal and desire by receiving hormones and changing the balance of neurotransmitters, but as you can imagine, there is neurobiology to all four of those. Attempting to understand some of the following questions has consumed my lab for the last twenty years:

What are these systems in the brain? How do drugs or stimuli in the environment activate them? Can you learn new things that turn you on? When you have that first mind-blowing orgasm, is that associated with all the prior experiences that led up to it? And maybe even all of the other individuals that led up to that?

PLAYBOY: How does arousal differ from desire?

PFAUS: Arousal is not simply getting a penile or clitoral erection; it is the brain’s ability to say “I am aroused,” and being consciously aware of that arousal. But desire (“feeling horny”): that involves feelings of intent. Do you intend to pick someone up? Do you intend to have sex? Did you wear your lucky socks? Did you remember the condom in your wallet? There are all these things that indicate that you think something is going to happen.

PLAYBOY: So let’s say somebody remembered to slip a condom into their wallet, but once they begin hooking up they ditch it. Is that the brain’s fault? Are we less likely to use a condom once aroused?

PFAUS: That’s decision-making. When something is there in front of you, you have a very different model of how to make that decision than when you think about it. Some people just don’t want to be controlled. They want to be able to let go and do something spontaneous, which can get derailed with concerns like putting on a condom. A more spontaneous individual is going to just go for it, but the more inhibited individual is going to be like, “Oh hold on. Wait a minute and let me look for my condom.” And then ���Oh my god, the condom is not in my wallet. Should I go to the pharmacy and go get one?”

John Bancroft [a Kinsey Institute sexologist] had this idea that people who are prone to inhibition are also prone to dysfunction: It’s way too easy to manipulate the system to say no, both physiologically as well as psychologically, than it is to get the system to say yes. But as you can imagine, certain drugs like alcohol inhibit those inhibitory centers and could disinhibit a person. So there might be someone who always uses a condom, but last night they got drunk and forgot to use one.

PLAYBOY: So universally, does alcohol curbs inhibition?

PFAUS: Alcohol is funny: low doses are really good at lubricating the system if you are inhibited. But if you aren’t, low doses of alcohol screw you up and inhibit you.

It’s also an anaesthetic, which can make women feel like, “Oh you’re inside of me now? Oh, okay,” or “Ok, you can whack my clitoris because I can’t really feel it.” With alcohol, it’s often like “harder, harder, harder.” And the guy may be able to go “harder, harder, harder” because he is drunk and his semi-limp penis is able to have sex for hours (which he then will brag about to friends). But the thing is: neither of you came and you might have thrown up on each other. Alcohol can be weird that way.

PLAYBOY: Your work has shown that if female rats expect bad sex from a potential partner, they will avoid that male rat. So is sexual inhibition for females—whether it’s a lack of interest or a restraint of desire—learned, not natural? What about with humans?

PFAUS: When clinicians interview women with a lack of sexual desire, the women will often say things like “I don’t really touch myself; I think my vagina is icky; it’s dirty down there.” There’s nothing innate about that. What’s innate is girls discovering the pleasure of the bathtub faucet. But perhaps these same girls masturbated at age six and then got punished for doing so. Now they think they’re dirty and don’t touch themselves. They’ve incorporated that into part of who they are and it’s going to take a long time to undo. And as the behaviors of the rats show, some of this dysfunction never gets undone. Some women may never have sex for their own pleasure, all because of a learned response that nothing good really happens from sex.

PLAYBOY: And this learning begins with our first sexual experiences, right? Is it true that our first times having sex shape shape our entire sexual identity and trajectory?

PFAUS: I can’t tell you exactly because we are early into that set of studies, but we are finding that there are changes in gene expressions—not just in neurons and synapses, but in actual gene expression—around the bonding mechanisms that are all conditioned by the reward.

So if the reward is really good that first time or first set of times that you get conditioned, your oxytocin neurons [a bonding hormone that reduces social distance] are now much more likely to be activated by the external cues that are associated with the activation of the reward.

PLAYBOY: So if you’re conditioned to orgasm, you’re more likely to be stimulated by the cues that you know have gotten you there before?

PFAUS: You are more attentive to those cues. When you’re hungry, food cues come out. When you’re thirsty, water cues come out. When you’re horny, partner cues come out. Whereas if you’re scared sexually, everyone can look like a spider.

PLAYBOY: What if a woman has amazing sex with a new guy the first time, and then after that it’s kind of unexciting?

PFAUS: Even if that person doesn’t really get you there the next five times you have sex, one time out of six is partial reinforcement. You’re like a used car salesman: ”I have had a run of bad luck, but, oh yeah, I’ll get four aces now.” If people get together and consistently have really good sex, the opposition of inhibition occurs. But if your expectations were high and you get together and it’s a disaster, it’s even more of a disaster.

PLAYBOY: Are guys more likely to fall in love with a woman after they’ve had sex with her?

PFAUS: Some boys fall in love with the people they have sex with, and some boys have sex with the women they pine for. But they aren’t just pining; they are beating off thinking about her. People don’t talk about masturbation enough. When you are thinking and fantasizing about someone, those individuals become people in your life.

PLAYBOY: More like objects in your life, right?

PFAUS: Yes, and there is nothing wrong with that, necessarily. If all you do is objectify, then you are not realizing that the other person is a multi-dimensional human being. But when you are having sex, are you going to have a feminist book-club discussion? I don’t think so. You’re going to fuck each other. Even the most gold star lesbians aren’t going to fuck each other and say, “Wow, sex with you is so political. Can I have a discussion when we are rubbing our clitorises together because I think this is really cool?”

No, no, no. It’s amazing to me that after sex, we have this very inhibitory, almost moralistic evaluation—”Don’t objectify me as a sex object.” When they are horny, everybody wants to be a sex object for as many people as possible. We want to feel desired, and not desired in a holistic way. You’re tits, ass, pussy, clit, wetness, and licking.

We also want someone to tell us the way we do what we do is incredible. We want to hear that we are superlative.

PLAYBOY: People perform better when their strengths are recognized.

PFAUS: It’s really easy to talk about someone’s faults. This happens sexually too. A lot of couples have really great sex and then don’t talk about it. They only really talk about their sex when things get shitty. But when they have really great sex, it’s not like “Wow, baby, what do you think we did? Why do you think it felt that way? You felt it too right? What did we do? Let’s have a discussion about what did.”

Surely we would do this if we cooked:

“Wow I have never had this before; this is amazing.”
“Well, this time I added chipotle.”
“Wow you added chipotle?”

You would deconstruct this without any problem. So why do we destroy sex by not talking about things when they are very, very good?

PLAYBOY: Surely guys are socialized to feel proud of their own sexual pleasure more than women are. But who do you think actually understands that pleasure more, men or women? Is it equal?

PFAUS: It all depends. A lot of women have been so restrained culturally and experientially that they have no idea what they like, and they aren’t with anyone who gives enough of a shit to help them figure that out.

Guys suffer from that even more. Whereas women might not understand that their clitoris is both external and internal, or know much about their cervix and the rest of labia and why things happen, they understand the rest of their body. Women know their nipples are really sensitive. They know the sensitive parts of their ear lobe and neck and inner thigh, because people go there. But guys don’t know their ass from a hole in the ground when it comes to that. Guys don’t like our nipples stimulated because we’re like, “What are you doing? I’m already erect.”

PLAYBOY: So guys know less about their own erogenous zones?

PFAUS: Guys have absolutely constrained our sexuality to our penises. The rest of our body isn’t even there. In one of the psychology classes I teach, I’ll ask the guys about enjoying a nice finger up their ass and getting their prostate massaged. They look at me like I’m crazy.

I once asked, “Okay, how many of you guys like your nipples stimulated?” And one of the guys actually blurted out “Uh that’s really gay.” So only gay men can get their nipples stimulated? I’m like, wow, how ridiculous is that? A lot of guys blush and say, “Oh no, I would never do that.” And I’m like, “Oh really, so why are you blushing?” What’s going on there? And suddenly they’re like “Let’s talk about something else because that’s really gay.” Why do we do that? It’s stupid.

PLAYBOY: Sounds accurate. You seem to be knowledgeable about sex from a bunch of different disciplines, not just neurobiology. Why and how did you become a bona fide sexpert?

PFAUS: When I was eleven I had my first orgasm and it was pretty fucking intense. My body had never done that before. I was like “Oh my god, what was that?” Right away I bought Human Sexual Response by Masters and Johnson. But nothing specifically told me why an orgasm felt good. So it really wasn’t until I got to grad school that I could look into this stuff.

PLAYBOY: Is there a reason why really good sex make us think we’re in love?

PFAUS: There is nothing more synchronous than having sex. We do our little dance, and our dance not only involves getting closer to one another, but also showing similar behaviors to each other. If you were to touch your hair and I were to touch my hair, its almost like monkey-see-monkey-do. You’re telling me you’re doing something I want to be in sync with, and I’m showing you that I want to be in sync with you. And then the legs kind of touch, and then the feet touch each other, and eventually someone kisses the other person.

The synchrony is around the question—does this person do me the right way? Does this person respond to my rhythm? Is a dude imposing snake tongue on you when all you want is something more slow and teasing around your clit? If he is doing what’s sensitive to your body and if you cum, and then he holds you, he’s a keeper. Right then and there you just crossed a line into bonding, and the brain is now activating all these monogamous circuits saying, “He’s a keeper! He does me!” And you wonder, “How can he possibly know me without knowing me? How magical is that? Have I met my soul mate?”

PLAYBOY:Why is it so hard to know if someone is your soulmate or just good at sex?

PFAUS: That becomes a problem. If he’s going to cuddle with you a little bit after, and then when he’s finished, get up and leave—that’s going to break your heart.