"Five Surprising Ways Oxytocin Shapes Your Social Life" by Jeremy Adam Smith originally appeared on Greater Good, the online magazine of UC Berkeley's Greater Good Science Center. You can view the original article here.

It’s been called the cuddle hormone, the holiday hormone, themoral molecule, and more—but new research suggests that oxytocin needs some new nicknames. Like maybe the conformity hormone, or perhaps the America-Number-One! molecule.

Where does this many-monikered neuropeptide come from? Scientists first found it in mothers, whose bodies flood with oxytocin during childbirth and breastfeeding—which presumably helps Mom somehow decide that it’s better to care for a poopy, colicky infant than to chuck it out the nearest window. And, indeed, one study found a shot of oxytocin more rewarding to rat-mommies than a snort of cocaine. (Don’t worry, Dads: You can get some of that oxytocin action, too.)

As time went on, researchers found oxytocin playing a role in all kinds of happy occasions, from social activities (recognizing faces at a party) to more intimate ones (achieving orgasm with someone you met at that party). Lab tests found that oxytocin made people more trusting, more generous, and more gregarious. Thus oxytocin seemed, for a little while, to deserve its glut of touchy-feely nicknames.

In the past few years, however, new research is finding that oxytocin doesn’t just bond us to mothers, lovers, and friends—it also seems to play a role in excludingothers from that bond. (And perhaps, as one scientist has argued, wanting what other people have.) This just makes oxytocin more interesting—and it points to a fundamental, constantly recurring fact about human beings: Many of the same biological and psychological mechanisms that bond us together can also tear us apart. It all depends on the social and emotional context.

The research is ongoing, and scientists are still debating how their findings fit together. But here’s a round-up of recent discoveries about oxytocin, boiled down to five cuddly and not-so-cuddly ways it might shape your social life.

1. It keeps you loyal to your love—and leery of the rest.

Men are dogs, right? They just want one thing, huh? Well, not if they’re jacked up on oxytocin. In fact, if they’re already in a loving relationship, they can become downright unfriendly to the opposite sex, according to a 2012 study in the Journal of Neuroscience.

Fifty-seven hot-blooded, heterosexual German men sprayed either oxytocin or a placebo up their own noses—and were then sent, alone, into a small room with beautiful young woman holding a clipboard. The questions she asked were irrelevant; instead, these scientists were measuring how close the men stood to the temptress as the two talked. (Here’s a tip: When you walk into a lab, never trust an experimental psychologist—those people are liars).

It turned out that if an oxytocin-snorting guy was already in a relationship, boyfriend actually kept his distance from his lovely interlocutor. Partnered guys who sniffed the placebo leaned in a little closer than their partners might have liked. The single guys, meanwhile, were probably too busy staring down her cleavage to hear the questions.

So oxytocin doesn’t simply make you all lovey-dovey, suggests this study. It also keeps you faithful to your partner—and wary of her rivals.

2. It makes us poor winners and sore losers.

Let’s say you’re playing a nice friendly game of poker. You like the people you’re playing with, you’re enjoying yourself. Until you start losing. The bastard on the other side of the table shows four of a kind or a full house every single time, and you can’t even get a pair. Damn him; he must be cheating. But then one hand later, you lay down a straight flush and take all his chips. Are you gracious? Hell, no. You light a cigar and gloat like a goat.

You might be surprised to hear that your posterior pituitary gland was probably secreting oxytocin through every step of that game, from the good feeling to the envy to the taunting. Quite a few studies have found that people dosed with oxytocin are more likely to spite their opponents when playing games of chance, which has led Andrew Kemp of the University of Sydney to argue that oxytocin plays a role in what psychologists call “approach-related” emotions—ones that have to do with wanting something from someone.

What about the friend who lost the game? You may have just lost that particular poker buddy—and again, oxytocin may play a role. If your friend is a mouse, anyway.

Researchers at Northwestern University put three groups of cute, gentle mice in a cage with another pack of crazy, aggressive ones. One of those three groups of mice had their oxytocin receptors removed. The other group had more receptors than usual. The third was normal.

All three groups were equally mauled by the psycho-mice, until the researchers rescued them. Their whiskers twitched, their pink noses happily wiggled—those mice thought they were safe.

But then, six hours later, scientists put the three groups back in the cage with the psycho-mice. (Remember, folks: Never trust an experimental psychologist.) Guess what? The oxytocin-free mice didn’t remember the mauling and didn’t know to run away, poor little guys. The other two groups scattered in fear.

The study, published in July by Nature Neuroscience, suggests that oxytocin strengthens social memories in the lateral septum, which has the highest oxytocin levels in the brains of both mice and humans. Yes, oxytocin is involved with attachment and social bonding, but that neural system can get tangled up in fear and anxiety—it gives us a visceral memory of those who have harmed us, as well as those who have cared for us.

The takeaway? If you beat the pants off your friends at poker and you want to play with them again, don’t gloat—but if you do, be sure to first remove their oxytocin receptors.

3. It makes you cooperative with your group—sometimes a little too cooperative.

Now, say you’re a single male chimpanzee. You enjoy sleeping in trees, attacking rival males, mating with random females, and eating the bugs you find in the fur of your friends.

Those bugs are tasty, but according to a studypublished in March, there’s at least one more benefit from grooming your chimp buddies: an oxytocin boost. Research finds that this reduces any stress that may have accumulated during a busy day of vying for the alpha male position.

Humans generally engage in other kinds of affiliative behaviors. I like to see movies with my human friends—but, hey, if you like eating bugs off yours, I for one will not judge you. Because just like other primates, studies find that oxytocin plays a critical role in helping us become more relaxed, extroverted, generous, and cooperative in our groups.

Sounds utopian, doesn’t it? Perhaps a little too utopian. Mirre Stallen and colleagues dosed Dutch study participants with either oxytocin or a placebo, and then divided them into groups of six. Each group watched a series of images and the individuals in the group voted for which ones they found most attractive. The results: The oxytocin-influenced participants tended to go with the flow of their group, while the placebo-dosed participants hewed to their own individualistic path.

The implication: Oxytocin is great when you’re out with friends or solving a problem with coworkers. It might not be so great when you need to pick a leader or make some other big decision that requires independence, not conformity.

4. It makes you see your group as better than other groups (to a point).

So far, dear reader, I’ve cast you in the roles of a hot-blooded lover, a poker-playing sore loser, and a chimp. Now let’s pretend you’re Dutch.

If a group of researchers in the Netherlands dosed you with oxytocin, you might find yourself developing a sudden affection for windmills, tulips, totally legal soft drugs and prostitution, and tall, blonde, multilingual bankers. You might also decide that the life of a Dutch person is more valuable than that of, say, a Canadian.

That’s exactly what Carsten De Dreu found in 2011. His study was sternly criticized for overstating its effects—and yet it’s not the only one to find that oxytocin seems to make us really, really, really like our own groups, even at the expense of other groups.

But loving our own groups doesn’t necessarily lead to hating other groups. Paul Zak’s lab at Claremont Graduate University has taken blood samples from members of campus groups like ROTC cadets and dance troupes. Then the groups perform some typical ritual—the cadets march, the dancers learn new steps together—and Zak and his minions draw more blood.

Zak isn’t a vampire. He’s not even an experimental psychologist; he’s actually an economist, so obviously you can trust him (right?). Being an economist means that his experiments always come down to money. He had those cadets and dancers play a series of trust and sharing games that ultimately earned them an average of $56 in real money. At the end, they could donate money to their own group or to a random charity.

That’s where things get nuanced. Yes, performing that ritual increased oxytocin counts by about 10 or 11 percent, but did cadets start favoring their team more than others? Across all 400 participants in his studies—this number of blood samples must make Zak the bloodiest economist in history—the increased oxytocin did not predict where they donated their money.

But there are some caveats. The more marginalized a group felt on campus, the more likely they were to circle their wagons and favor their own in-group (presumably, the band nerds weren’t as generous as frat boys to other groups). The effects of oxytocin could also change depending on what else was happening in the body: If Zak’s lab induced stress or acted to jack up testosterone, participants could, in fact, become more aggressive toward out-groups.

Which leads us to our final item…

5. It does make us trusting—but not gullible.

The research I’ve described so far probably sounds pretty great. If you’re a dictator. Or Don Draper—think about all the defective products you could sell by blowing oxytocin into the air.

Face it, we all want to rule the world sometimes, and I can certainly understand the desire to keep everyone else docile, compliant, and hostile to out-groups. The drug “soma” from Aldous Huxley’s Brave New World probably contained some oxytocin. The two-minutes hate in Orwell’s 1984 probably got the oxytocin pumping as well.

But before you start getting excited, you wanna-be dictator, there’s one more bit of new research you should know about: Studies find that we can cognitively override oxytocin-driven impulses.

Several experiments suggest that while oxytocin makes us more generous and trusting, it does not make us more gullible. If we have evidence that someone is deceiving us, we can withdraw trust and resources no matter how high we are on oxytocin. If we think someone doesn’t have our best interests at heart, we can end the relationship with a person or a group.

But the effects go beyond self-interest. We may like being part of a group so much that we’re willing to hurt others just to stay in it. The desire to belong can compromise our ethical and empathic instincts. That’s when the conscious mind needs to come online and put the brakes on the pleasures of social affliliation.

Your mom was right about keeping good company, says Paul Zak: “We do have to be in the right environment to be virtuous.” That might be the bottom line with oxytocin—and, indeed, any neural system that bonds us to other people: The impulse to join and conform in a group is always very strong in human primates, and so the key lies in choosing the right group—and then not getting carried away.