Can One Chemical Be the Basis of All Morality?

A Techwise Conversation with Paul Zak, author of The Moral Molecule

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Steven Cherry: Hi, this is Steven Cherry for IEEE Spectrum’s “Techwise Conversations.”

We’ve known for some time that our behavior is governed, at least in part, by our biochemistry.

For example, in the classic fight-or-flight response to danger, the hypothalamus causes the release of a number of hormones, such as ACTH and epinephrine. Contrawise, abnormal levels of thyroid gland hormones can make people lose interest in their career, friends, and love life.

Mostly, psychiatrists and neuroscientists have focused on bad affect and bad behaviors—people generally don’t go to the doctor because they’re feeling particularly fine or because they’re always doing the right thing.

Lately, though, one substance in our bodies has been getting a lot of attention for all the good it’s been doing. And no one has been studying it more zealously than my guest today.

The substance is oxytocin, and my guest is Paul Zak. He’s a professor of economics, management, and psychology—a combination we’ll be asking him about in a bit—at Claremont Graduate University, and he’s the author of a book being published this month by Penguin, entitled The Moral Molecule: The Source of Love and Prosperity.

He joins us by phone from New York.

Paul Zak: Thank you, Steven.

Steven Cherry: Paul, reading your book I get the idea that you would walk around all day with a centrifuge in your backpack if it didn’t weigh 150 pounds. Tell us about a wedding where you did show up to with a centrifuge and some dry ice after flying 6000 miles, I guess.

Paul Zak: That’s right. So I was invited to a wedding in England in which I didn’t know the bride or the groom or anybody there, in fact, and I showed up in my lab coat and centrifuge and dry ice and needles and syringes, and with permission I took blood from the bride and the groom and the wedding party to find out why we have weddings. Right? Why do we spend fifty or a hundred thousand dollars on a big ceremony when we could be putting a down payment on a house? So we took blood right before the wedding vows and immediately after, and so what I found was data that’s so perfect, you couldn’t make it up this good—so that’s a technical term. Basically, the bride had the highest release of oxytocin; she is the center of the wedding solar system. And then, who loves the wedding almost as much as the bride? Her mother. She had the second-highest release of oxytocin, and then the groom’s father, the groom, the family, the friends—so the oxytocin told us about the kinds of relationships in this ceremony and that the ceremony itself was inducing this emotional bonding to the couple who are the center of the ceremony. So two things we can take from that: Number one is that these rituals are not dumb. They’re very good uses of money because they essentially bond a whole bunch of people to that couple who can help that couple be successful, and from a biological perspective successful means reproducing. So your kids need someone to marry; my kids need someone to marry; and so this ceremony helps us ensure that the population is perpetuated. But second, it also tells us how oxytocin modulates social behaviors, right? So if you don’t feel that close to the bride and groom, you might get a little hit of oxytocin or nothing at all, and if you’re very close to them this ceremony brings out that sense of connection to them. And so oxytocin is this kind of modulating mechanism that really hadn’t been found until about 10 years ago when I started doing experiments on human beings—measuring it.

Steven Cherry: Yeah. So we should point out that you’ve done a lot of these different experiments: You’ve traveled to Papua New Guinea; you’ve jumped out of airplanes; you’ve studied crustaceans. And mainly you’re doing this measuring the before and after levels of this one chemical in the bloodstream.

Paul Zak: That’s right—and really asking, what does it do? So until 10 years ago, oxytocin was only known in humans to do three things: to facilitate birth, to facilitate breast-feeding, and to be released by both sexes during sex. But in the animals it was known to facilitate things like toleration for burrow mates. So I had this idea that oxytocin, which men release as well as women, might be doing something more in human beings.

Steven Cherry: Yeah. So I assume that like everything else in the body, oxytocin is part of a whole system that tries to regulate itself. Tell us how it works and what happens when it isn’t working well.

Paul Zak: Right. So I think of oxytocin as kind of a thermostat. So humans are social creatures; we need to engage in appropriate social behaviors. And most of those appropriate behaviors are called “virtues” or “moral behaviors,” so if I’m cooperative with you, if I share with you, I’m a good social creature. If I take from you, if I’m selfish, I’m not a good social creature, and then you start to avoid me, and that’s not adaptive for social creatures. So we’ve shown in experiments that when we stimulate the brain to release oxytocin or when we raise it pharmacologically, that we can induce people to be more prosocial, more moral, more virtuous. At the same time, as you say, oxytocin interacts with a variety of other neurochemicals, including things like stress hormones and testosterone, which...both those down-regulate oxytocin’s effects. And so we’re kind of living in this soup of chemicals in our brains, and the relative levels of oxytocin and other chemicals that interact with it—testosterone, cortisol, dopamine—modulate the kind of appropriate social behavior.

Steven Cherry: Your background, we mentioned, is really that of an economist, and one of the big tests of your theory came from running something called the “trust game.”

Paul Zak: That’s right. So I’m kind of cross-trained in economics and in neuroscience. And so one of the issues I took on as an economist in the late nineties was why countries are poor—kind of one of the eternal questions, right? And I found that levels of interpersonal trust were among the strongest predictors economists had ever found to understand why countries are rich or poor. So, high-trust countries are rich countries, and by and large, low-trust countries by and large are poor countries because if you don’t have trust, you don’t really facilitate transactions that can create wealth and reduce poverty. And this work actually had a lot of impact. The World Bank flies me out—you know, how do we raise trust in these developing countries? But I always got this question, which is: In a given country, why would you ever trust a stranger? And that seemed to me a fundamentally important question if we wanted to use this research to reduce poverty.

And so I used a laboratory task that the founder of experimental economics, Vernon Smith, invented, in which you can transfer money in the laboratory to a stranger and if you do that, you have to give up that money, but the stranger’s money increases threefold. So if I have 10 dollars and I, say, transfer by computer 8 of my 10 dollars to you, I only keep 2, but now you’ve got 24. And then the second person gets a message by computer saying, “Guy 1 sent you 24 dollars—do you want to send some amount back to the first person?” So a very simple task, now called the “trust game,” and economists were flummoxed on why you would ever send money to a stranger because they assume that strangers, like most people, like money and would keep any money you sent them. But in fact almost nobody does that, and in fact the people that do are very interesting. So what we found is that in this laboratory task, the more money a stranger sends you denoting trust, the more your brain produces oxytocin, and the more oxytocin in your bloodstream, the more money you reciprocate. So it tells us we have an underlying biology for reciprocation. Again, as social creatures, that makes sense. It just allowed—this little probe allowed us to interrogate the brain to find out what that mechanism was, and knowing the mechanism as all engineers know allows you to really fine-tune the system.

Steven Cherry: Yeah. So I guess there are consequences here on the individual level and on the societal level. But I guess to follow up on the individual level, can you picture a world in which we really do want to directly affect people’s oxytocin levels? I mean, I can picture, maybe, a judge and jury sort of mandating oxytocin therapy to someone who engages in antisocial behavior of the criminal kind.

Paul Zak: That’s a great question, and unfortunately everything in biology is more complicated than we think. So we found about 95 percent of the thousands of people we tested around the world, as you said, even in the jungles of Papua New Guinea, release oxytocin on stimulus, so it seems to be close to a human universal. The 5 percent who don’t are very interesting. In these individuals, they have an ex ante identifiable oxytocin dysfunction that likely comes from the level of the receptors. So what does that mean in normal English? It means if I replace oxytocin, say pharmacologically, in these people, I’m not going to have much of an effect because the receptors are missing or dysfunctional. So it’s not as simple as that. For example, we about 1 or 2 percent of these individuals are psychopaths, and most psychopaths are born—some are made, and I’ll tell you about the ones that are made. But psychopaths kind of have a bad genetic draw and seem to lack these receptors, and again we can identify them biologically ex ante. You can create psychopaths. We’ve shown in studies of repeatedly sexually abused women that enough abuse will actually shut down the brain circuit that oxytocin activates—potentiatesand if you do that, you have a sort of acquired psychopathology. And the third is, you know, high stress. So as I mentioned earlier, high levels of stress hormones—you know, we’re not all at our best when we’re stressed out, and we’re not the nicest people sometimes. And so this 5 percent picks up all three of those. Yeah, so it’s not as simple as replacing that chemical. There is some interesting work right now coming out of Pfizer showing that they have in rats developed an oxytocin receptor agonist, so this is a drug that would increase the number of oxytocin receptors. Again, not tested yet in humans, but the work I’ve done in the last 10 years has spun a lot of clinical interest, which is very interesting, so I’m involved in clinical trials now for autism, schizophrenia—we’ve done work for social anxiety disorder. And so there may be applications pharmacologically for oxytocin, but so far we’re in the testing stages for that.

Steven Cherry: So, on the societal level your argument seems to be that trust is the basis of the golden rule, and the golden rule is—I guess, one version of it is the New Testament’s “Do unto others as you would have them do unto you”—that the golden rule is really the basis of all good social behavior.

Paul Zak: And in fact, the basis for economic exchange as well. So you know, so many of the institutions that we’ve developed are based on that golden rule. So democracy, right? We send people to Washington or to Albany or Sacramento and hope that they’re going to do our bidding, so we obviously have to have oversight. But that’s a very decentralized system. You know, think of the global economy, eBay; you know, all of this is based on an underlying assumption that most people most of the time will behave properly. Now, if they don’t behave properly, you have some recourse, but it’s always imperfect. You know, any contracts you sign, people can wiggle out of it this way or that way, but most times, most ways, people find these win-win solutions. So oxytocin is really the foundation for civilization.

Steven Cherry: Combining the personal and the social, as I understand it your research suggests that reasonably high levels of oxytocin are kind of the normal state for us, which you then argue means that trust and moral behavior are the norms as well. That’s kind of surprising. I think many of us look at the animal world or early human society and see something more like Thomas Hobbes’s idea that the human condition is “solitary, nasty, poor, brutish, and short,” and it’s only through the tenuous miracle of the social contract that we get what you say oxytocin gives us automatically.

Paul Zak: Right. So the question is, where does that social contract come from? Why did we actually cede some of our personal liberty to have a government provide some rules? And part of the answer is that our moral intuitions are imperfect, and I’ll give you a concrete example of that. So, I already mentioned that stress hormones can inhibit oxytocin, but the favored hormone of half the human race, testosterone, is a potent oxytocin inhibitor. So in the experiments where we administer testosterone to men, we find that they become more selfish and more entitled. So: Who are the most selfish and entitled people on the planet? Teenage boys, which you and I used to be—and we can attest to that. But at the same time, we find that high-testosterone men are much more likely to spend their own resources to enforce social norms of sharing. That is, if given a chance to punish, it’s these high-testosterone individuals who will enforce the rules and punish others for not cooperating. So we have this sort of yin and yang of morality right inside our own beings. We have oxytocin that makes us care about other people, makes us feel empathy—it’s hard to hurt people you feel empathy for—and then we have testosterone, which lets us enforce the rules.

Steven Cherry: You know, I mentioned Hobbes, but your work is much closer to a different British philosopher, the economist Adam Smith. And you even mention his book The Theory of Moral Sentiments in your book. And my producer looked through her copy of Adam Smith and found some pretty similar sentiments to the ones you’re expressing right now, that society is, quote, “the most powerful remedies for restoring the mind to its tranquility” and that “man is by nature sympathetic.” Adam Smith was the leading proponent of capitalism—though maybe not the extreme version of capitalism we see advocated these days—but do you think oxytocin propels us towards one economic system or another?

Paul Zak: I think oxytocin propels us towards personal liberty, and, you know, we don’t really need God or government telling us every second of the day what’s appropriate to do because we have each other telling us that. So what Smith said in, I think, his most important book, The Theory of Moral Sentiments, is that because we share the emotions of others we tend to avoid things that hurt others because we’d feel that pain, and we do things that bring others pleasure because we get to share that pleasure as well. So we tend do those things...again, not always. And so knowing the neuroscience gives us much sharper predictions than Smith had. I just found the mechanism behind it. That Adam Smith is typically known for his second-best book—in my opinion—The Wealth of Nations, the so-called founding document of economics, which talks a lot about self interest—but self interest is not selfishness, and so I think those two books have to be read together to understand that I can be self-interested and still be a wonderful, caring human being. And I think the way we modulate that is very important. And sometimes we don’t say it. I think, as you said in your intro, the bad behavior gets all the press: the guys on Wall Street doing the perp walk, the bad behavior of some Hollywood star. But by and large, most of our lives are spent with people being at minimum neutral towards each other but at many times being quite caring and nice. And this comes from a variant in the gene for oxytocin that happened about two or three hundred thousand years ago, in which oxytocin causes release of dopamine in human beings—this chemical that’s rewarding, that motivates particular behaviors. And so human beings get a big oxytocin kick when we do something that helps others, and [the] oxytocin kick is rewarding through dopamine. So the punch line here is that it feels good to do good, and that’s actually interesting news, new news. Again, there’s lots of times when it’s appropriate for me to be aggressive or me to be completely self-interested, but most of the time, as a social creature, I want to cooperate with other humans because there’s great value in that.

Steven Cherry: Well, Paul, it’s a fascinating area, and we’ve just scratched the surface of everything you have to say in the book, so I guess our listeners are just going to have to go read it for themselves. There’s a link to it on the podcast page, or they can just go to, one word. Of course, they’ll have to spell molecule correctly, which for some reason is one of those words I always misspell. But thanks for writing the book, and thanks for joining us today.

Paul Zak: What a pleasure talking with you, Steven. Thanks so much.

Steven Cherry: We’ve been speaking with neuroeconomist Paul Zak about his new book, The Moral Molecule: The Source of Love and Prosperity. For IEEE Spectrum’s “Techwise Conversations,” I’m Steven Cherry.

Announcer: “Techwise Conversations” is sponsored by National Instruments.

This interview was recorded 9 May 2012.
Segment producer: Barbara Finkelstein; audio engineer: Francesco Ferorelli

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