When people watch Ben’s story in the lab—and they both maintain attention to the story and release oxytocin—nearly all of these individuals donate a portion of their earnings from the experiment. They do this even though they don’t have to. This is surprising since this payment is to compensate them for an hour of their time and two needle sticks in their arms to obtain blood from which we measure chemical changes that come from their brains. 

when rats are sizing each other up in the moments before a potential fight, which may mean that laughter can help diffuse situations that might otherwise escalate into physical conflict. Similar behavior has been documented among chimpanzees.

As rats age, their chirping generally becomes less frequent. (A similar phenomenon seems to occur in humans: Research done by William Fry, a professor emeritus at Stanford University School of Medicine, has found that kindergarteners laugh 300 times a day, whereas adults laugh just 17 times.) However, rats who were tickled often when young usually retain their tendency to chirp later in life.

It is precisely this more childlike, instinctive form of laughter that scientists believe they have uncovered in rats. Panksepp, the Baily Endowed Chair of Animal Well-Being Science at Washington State University, has found that rats emit their high-pitched chirps when tickled, especially in areas, such as the nape of the neck, that are targeted by fellow rats during playful bouts. They make the same sounds when playing or anticipating playtime with one another, as well as when anticipating a reward. Other research has found that this chirping is common when rats enter new environments or encounter new animals; Panksepp likens this to nervous laughter in humans.

scientists have probed the brain circuits involved in human laughter, but this research has faced a number of limitations. For one, though researchers have used sophisticated equipment to observe people’s brain activity while they read cartoons or jokes, this equipment is quite sensitive to movement—a major drawback when you’re trying to induce a hearty belly laugh.

Experiments on humans have found that laughter can increase blood flow and strengthen the heart, much like aerobic exercise does. Laughter also helps decrease one’s threshold for pain, although not all humor is the same in this respect. According to Weems, positive humor—humor that looks for the bright side of troubling situations—is beneficial to our health, while darker, sardonic humor is not.

Take for example an old Groucho Marx joke: “One morning I shot an elephant in my pajamas. How he got in my pajamas, I don’t know.” Our brains will read the first sentence and be taken down a path imagining Grouch Marx on a safari in his pajamas, before we get the new image of the elephant actually inside his pajamas. That process of moving from one possible solution to the next involves a part of the brain called the anterior cingulate, or AC, which becomes more active when there are conflicting interpretations in the brain. The AC helps to quiet down the “louder” parts of the brain (associated with the expected response) to allow other quieter answers to emerge, and it’s particularly active during jokes. It helps us to figure out the novel solution, which, when resolved, gets incorporated into the brain and gives us that spike of dopamine. This is why we feel so good when we get a joke, and why jokes are not funny the second time around.

he grouped humor preferences into three types: “incongruity-resolution,” which involves “violating one’s expectations in novel ways;” “nonsense humor,” “which is funny only because it makes no sense;” and “sexual humor,” which is offensive or taboo. Although not everyone finds the same type of humor funny, the common thread in these joke types is that they all involve dealing with surprise and resolving the ensuing cognitive dissonance. “What elicits laughter isn’t the content of the joke but the way our brain works through the conflict the joke elicits,” writes Weems. Basic Books, 2014, 230 pages

Weems explains what humor is, how things become funny, and why evolution gave us laughter. According to Weems, laughter and humor help us process conflict in our environment through the dopamine that is released in our brains when we find something funny. Dopamine relieves tension—which I discovered with my son—but it’s also implicated in motivation, memory, and attention, affecting processes as varied as learning and pain management.

laughing, probably through its effects on breathingwhich makes you breathe more deeply, actually calms your cardiovascular system. So, it reallyseems to be altering your stress profile as a pathway to physical health.

In answer to why awe would be a potent predictor of reduced pro-inflammatory cytokines, this latest study posits that “awe is associated with curiosity and a desire to explore, suggesting antithetical behavioral responses to those found during inflammation, where individuals typically withdraw from others in their environment,” Stellar said.

In addition to autoimmune diseases, elevated cytokines have been tied to depression. One recent study found that depressed patients had higher levels of the pro-inflammatory cytokine known as TNF-alpha than their non-depressed counterparts. It is believed that by signaling the brain to produce inflammatory molecules, cytokines can block key hormones and neurotransmitters—such as serotonin and dopamine—that control moods, appetite, sleep and memory.

There are new psychophysiological findings finding that cytokine levels, cytokinesreally reflect an inflammation in response in your body, which is very tough news onyour health, the only positive emotion that really lowers levels of cytokines is provingto be awe.

E.O. Wilson’s writing about biophilia.And it’s really this very rich hypothesis that we have this evolved love about naturalbeauty. So if you’re out in the woods, you’re in the mountains, you’re watching patternsof light on the ocean, it triggers this feeling in us, this feeling of beautiful delight ifyou will. And E.O. Wilson makes the case that that is an evolved preference because whenwe attach to beautiful things in nature, we’re finding kind of resource-richenvironments that have food and water and shelter as a way to orient towards thelandscape.

busy regions of the brain start stitching new connections with each other. Existing synapses—the connections between neurons that are very busy—get stronger, they get more sensitive, they start building out more receptors. New synapses form as well.

more activation in the left prefrontal cortex is associated with more positive emotions. So as there is greater activation in the left, front portion of your brain relative to the right, there is also greater well-being. That’s probably in large part because the left prefrontal cortex is a major part of the brain for controlling negative emotion. So if you put the breaks on the negative, you get more of the positive. On the other hand, people who routinely experience chronic stress—particularly acute, even traumatic stress—release the hormone cortisol, which literally eats away, almost like an acid bath, at the hippocampus, which is a part of the brain that’s very engaged in visual-spatial memory as well as memory for context and setting. For example, adults who have had that history of stress and have lost up to 25 percent of the volume of this critically important part of the brain are less able to form new memories.

And better understanding them means we can skillfully stimulate the neural substrates of those states—which, in turn, means we can strengthen them. Because as the famous saying by the Canadian scientist Donald Hebb goes, “Neurons that fire together, wire together.”

Mindfulness interrupts the conditioned responses that prevent us from exploring new avenues of thought, choking our creative potential. Each time we stand up against a habit—whether it’s checking our smartphone during a conversation or reacting defensively to a coworker’s passing remark— we weaken the grip of our conditioning. We lay down new tracks in the brain  and fashion new synaptic connections.

Participants for the gene study came into the lab and meditated for eight hours. Blood samples were taken before and after those hours of practice and then Davidson and crew looked for gene-expression changes over the course of that time in the lab. Results from this meditator group were compared to a control group that was not familiar with meditation and that came into the laboratory for “a day of leisure.” That group watched quiet videos, read, and took gentle walks. The findings? The control-group participants didn’t show the same kind of gene-expression changes, Davidson says. It’s the first study that shows “we can actually see gene-expression changes within a very short period of time.”

“One of the important foci in our research is looking at inflammation, which has been implicated in many chronic illnesses,” Davidson says. “And there’s now increasing evidence to suggest that at a very basic biological level, certain kinds of meditation practices seem to modulate inflammatory systems. They down-regulate particular molecules—we call these proinflammatory cytokines—which are directly implicated in inflammation.”

also did a briefmeditation intervention and in their subjects they were able to show that themeditation program resulted ina greater activation in reward circuitryso more contentment and pleasure and in this caseanticipatory pleasure because they were showing this activationin response to opportunities, to help opportunitiesto be of assistance.

basically what they've been able to showis that certain regions of the brain seem to getmore densely interconnected and more responsiveafter meditation and those ones seem to be areas of the brain that areinvolved inwhat we call interoceptive awareness, which is also the same area that’s implicated in empathy so so we get stronger at responses in our in our insula in response to information from the outside world after having participated in a meditation programathis should make us more empathetic, and thisindeed that’s what we observed.

Neuroplasticity is the idea that our brains change throughoutlifeas a result of day-to-day experiences and activities.

And what they found was that the individuals who participated in the meditation programhad longer telomeres than the individuals who were in the control group after a three-monthexperience. This was first finding in that vein. Elissa Epel and her colleague did anotherresearch project where they looked at a mindfulness-based program for people with eating disorders andshowed that people who did the mindfulness had a 39% increase in telomerase activitywhich corresponds to lengthened telomeres and that this telomerase activity actuallypredicted benefits in other aspects of their treatment program having to do with the people’seating habits. So there’s this interesting effect that is being reiterated that mindfulnessactually seems to make people age more gracefully.

during periods of mind-wandering, regions of the brain’s default mode network were activated. Then when participants became aware of this mind-wandering, brain regions related to the detection of salient or relevant events came online. After that, areas of the executive brain network took over, re-directing and maintaining attention on the chosen object. And all of this occurred within 12 seconds around those button presses.

A particularly generative field is contemplative neuroscience, which involves collaborations between scientists and expert authorities in the traditions that have informed the concept of mindfulness.

For example, when your mind wandered off in that meeting, it might help to know you’re slipping into default mode—and you can deliberately bring yourself back to the moment. That’s an ability that can improve with training.

One brain area stood out in this analysis: the medial prefrontal cortex, a part of the default mode network that is particularly related to self-focused thoughts, which make up a good portion of mind-wandering content. It turns out that experienced meditators deactivated this region more quickly after identifying mind-wandering than people who hadn’t meditated as much

more experienced meditators have increased connectivity between default mode and attention brain regions, and less default mode activity while meditating.

a wandering mind isn’t all bad. Not only can we leverage it to build focus using FA meditation, but the capacity to project our mental stream out of the present and imagine scenarios that aren’t actually happening is hugely evolutionarily valuable, which may explain why it’s so prominent in our mental lives. These processes allow for creativity, planning, imagination, memory—capacities that are central not only to our survival, but also to the very essence of being human. The key, I believe, is learning to become aware of these mental tendencies and to use them purposefully, rather than letting them take over. Meditation can help with that.

the Killingsworth and Gilbert study I mentioned earlier found that when people’s minds were wandering, they tended to be less happy, presumably because our thoughts often tend towards negative rumination or stress. That’s why mindfulness meditation has become an increasingly important treatment of mental health difficulties like depression, anxiety, post-traumatic stress disorder, and even sexual dysfunction.

To some people, these findings about oxytocin might raise another concern: that trust is not subject to rational control—that it’s “all hormones.” This seems to stand in stark contrast to the traditional idea of trust being the outcome of a cognitive, rational process. In my view, trust is both, just like other human social behaviors. We cannot deny that many of our decisions are governed by cognitive processes; in the case of trust, these processes take into account the available information about the trustee’s motivation, the likelihood of a repeated interaction, and so on.

Interestingly, the investors’ expectations about the back-transfer from the trustee did not differ between the oxytocin and placebo recipients. Oxytocin increased the participants’ willingness to trust others, but it did not make them more optimistic about another person’s trustworthiness.

there is a simple hypothesis about what steers the human brain to trust another human: a hormone called oxytocin.

British researchers Peter Woodruff and Tom Farrow are doing some of this important work. Their research suggests that the areas in the brain associated with forgiveness are often deep in the emotional centers, in the region known as the limbic system, rather than in the areas of the cortex usually associated with reasoned judgments. In one study, they asked people to judge the fairness of a transgression and then consider whether to forgive it or empathize with the transgressor. Ten individuals evaluated several social scenarios while the researchers recorded images of their brain activity. Whether people empathized or forgave, similar areas in the emotion centers of the brain lit up. When those same people thought about the fairness of the same transgression, though, the emotion centers stopped being as active. This could be a clue for interventionists. To help people forgive, help them steer clear of dwelling on how fair a transgression was or how just a solution might be. Instead, get people to see things from the other person’s perspective.

Hostility also has been found to be the part of type A behavior that seems to have the most pernicious health effects, such as a heightened risk of cardiovascular disease. Forsaking a grudge may also free a person from hostility and all its unhealthy consequences. It probably isn’t just hostility and stress that link unforgiveness and poor health. According to a review of the literature on forgiveness and health that my colleague Michael Scherer and I published, unforgiveness might compromise the immune system at many levels. For instance, our review suggests that unforgiveness might throw off the production of important hormones and even disrupt the way our cells fight off infections, bacteria, and other physical insults, such as mild periodontal disease.

To ruminate on an old transgression is to practice unforgiveness. Sure enough, in Witvliet’s research, when people recalled a grudge, their physical arousal soared. Their blood pressure and heart rate increased, and they sweated more. Ruminating about their grudges was stressful, and subjects found the rumination unpleasant. It made them feel angry, sad, anxious, and less in control. Witvliet also asked her subjects to try to empathize with their offenders or imagine forgiving them. When they practiced forgiveness, their physical arousal coasted downward. They showed no more of a stress reaction than normal wakefulness produces.

The first half of the twentieth century was drenched in the blood spilled by German and Japanese aggression, yet only a few decades later it is hard to think of two countries more pacific. Sweden spent the 17th century rampaging through Europe, yet it is now an icon of nurturing tranquility. Humans have invented the small nomadic band and the continental megastate, and have demonstrated a flexibility whereby uprooted descendants of the former can function effectively in the latter. We lack the type of physiology or anatomy that in other mammals determine their mating system, and have come up with societies based on monogamy, polygyny, and polyandry. And we have fashioned some religions in which violent acts are the entrée to paradise and other religions in which the same acts consign one to hell. Is a world of peacefully coexisting human Forest Troops possible? Anyone who says, “No, it is beyond our nature,” knows too little about primates, including ourselves.

Is it possible to achieve the cooperative advantages of a small group without having the group reflexively view outsiders as the Other? One often encounters pessimism in response to this question, based on the notion that humans, as primates, are hard-wired for xenophobia. Some brain-imaging studies have appeared to support this view in a particularly discouraging way. There is a structure deep inside the brain called the amygdala, which plays a key role in fear and aggression, and experiments have shown that when subjects are presented with a face of someone from a different race, the amygdala gets metabolically active—aroused, alert, ready for action. This happens even when the face is presented subliminally, which is to say, so rapidly that the subject does not consciously see it. More recent studies, however, should mitigate this pessimism. Test a person who has a lot of experience with people of different races, and the amygdala does not activate.

Working with captive primates, de Waal and Johanowicz created a mixed-sex social group of juvenile macaques, combining rhesus and stump tails together. Remarkably, instead of the rhesus macaques bullying the stump tails, over the course of a few months the rhesus males adopted the stump tails’ social style, eventually even matching the stump tails’ high rates of reconciliatory behavior. It so happens, moreover, that stump tails and rhesus macaques use different gestures when reconciling. The rhesus macaques in the study did not start using the stump tails’ reconciliatory gestures, but rather increased the incidence of their own species-typical gestures. In other words, they were not merely imitating the stump tails’ behavior; they were incorporating the concept of frequent reconciliation into their own social practices. Finally, when the newly warm-and-fuzzy rhesus macaques were returned to a larger, all-rhesus group, their new behavioral style persisted.

Kummer conducted a simple experiment, trapping an adult female savanna baboon and releasing her into a hamadryas troop and trapping an adult female hamadryas and releasing her into a savanna troop. The females who were dropped in among a different species initially carried out their species-typical behavior, a major faux pas in the new neighborhood. But gradually, they absorbed the new rules. How long did this learning take? About an hour. In other words, millennia of genetic differences separating the two species, a lifetime of experience with a crucial social rule for each female—and a miniscule amount of time to reverse course completely.

it suggests that maybe these prefrontal regionsthat are really important for decision making have to work a little bit harder when we decidenot to cooperate when we decide to compete or defect at the expense of the other person.

we experience pleasurewhen we cooperate knowing that our cooperation is going to lead to benefits to the peoplethat we’re cooperating with.

they found that reward signalling increased with reciprocated cooperation, inother words if I cooperate and I learn that you have alsocooperated then we’re both benefitting from this mutual cooperation there is greater rewardactivation or reward signalling gets boosted. And then also they found that when peoplecooperate but then are met with not cooperation in other words, unreciprocated cooperationdecreases activation in these reward processing areas.

suggest that lonely people have significantly more trouble bouncing back from life’s stresses and strains. For instance, lonely and non-lonely college students in their study reported similar daily activities, but lonely college students experienced more stress in those activities. Among older adults, lonely individuals said they felt more helpless and threatened than did non-lonely people. What’s more, higher stress levels were associated with worse health: Lonely college students had higher blood pressure than non-lonely ones, putting them at greater risk for heart disease, and this health disparity was even greater between lonely and non-lonely older adults. Plus, Hawkley and Cacioppo found that these lonely older adults had higher levels of stress-related hormones, such as cortisol and epinephrine, which may weaken the immune system over time.

Giving has also been linked to the release of oxytocin, a hormone (also released during sex and breast feeding) that induces feelings of warmth, euphoria, and connection to others. In laboratory studies, Paul Zak, the director of the Center for Neuroeconomics Studies at Claremont Graduate University, has found that a dose of oxytocin will cause people to give more generously and to feel more empathy towards others,

warm, sensitive parenting for three year olds predicts greater focused concentration in the children one year later—which in turn predicts greater sympathy at ages six and seven. Vagal tone in the kids at three years also predicts sympathy three and four years later. As was the case for parenting style, the Vagal tone effect was largely related to the children’s concentration skills as four years olds.  Together, these data suggest that warm, sensitive, authoritative parenting may support skills like managing emotions and focusing attention, and that children with higher Vagal tone are more likely to have these skills, which in turn paves the way for sympathy for other peoples’ suffering.

Dacher spoke about the Vagus nerve and its role in social connection and, in turn, happiness. In the essay below, Emiliana summarizes very recent research showing that Vagal tone, an index of the general strength of influence that a person's Vagus nerve has on their heart, predicts the emergence of sympathetic behavior over development--and further, that in college students, experiencing compassion actually engages the Vagus nerve. 

Pride doesn’t illicit and upregulation of vagal tone, pride instead causes very littlechange because again pride is self-focused as opposed to focused on others.

people who are feeling compassion engage their vagus system.

Recent neuroscience studies suggest that positive emotions are less heritable—that is, less determined by our DNA—than the negative emotions. Other studies indicate that the brain structures involved in positive emotions like compassion are more “plastic”—subject to changes brought about by environmental input.

Taken together, our strands of evidence suggest the following. Compassion is deeply rooted in human nature; it has a biological basis in the brain and body. Humans can communicate compassion through facial gesture and touch, and these displays of compassion can serve vital social functions, strongly suggesting an evolutionary basis of compassion. And when experienced, compassion overwhelms selfish concerns and motivates altruistic behavior.

Remarkably, people in these experiments reliably identified compassion, as well as love and the other ten emotions, from the touches to their forearm. This strongly suggests that compassion is an evolved part of human nature—something we’re universally capable of expressing and understanding.

breastfeeding and massages elevate oxytocin levels in the blood (as does eating chocolate). In some recent studies I’ve conducted, we have found that when people perform behaviors associated with compassionate love—warm smiles, friendly hand gestures, affirmative forward leans—their bodies produce more oxytocin. This suggests compassion may be self-perpetuating: Being compassionate causes a chemical reaction in the body that motivates us to be even more compassionate.

helping others brings the same pleasure we get from the gratification of personal desire.

What is the ANS profile of compassion? As it turns out, when young children and adults feel compassion for others, this emotion is reflected in very real physiological changes: Their heart rate goes down from baseline levels, which prepares them not to fight or flee, but to approach and soothe.

Evolutionary biologists like Frans de Waal have shown that we are social animals who have naturally evolved to care for each other, just like our primate cousins. And psychologists have revealed that we are primed for empathy by strong attachment relationships in the first two years of life.  But empathy doesn’t stop developing in childhood. We can nurture its growth throughout our lives—and we can use it as a radical force for social transformation.

We rely more on what we feel than what we think when solving moral dilemmas. It’s not that religion and culture don’t have a role to play, but the building blocks of morality clearly predate humanity. We recognize them in our primate relatives, with empathy being most conspicuous in the bonobo ape and reciprocity in the chimpanzee. Moral rules tell us when and how to apply our empathic tendencies, but the tendencies themselves have been in existence since time immemorial.

Bonobos are less brutal, but in their case, too, empathy needs to pass through several filters before it will be expressed. Often, the filters prevent expressions of empathy because no ape can afford feeling pity for all living things all the time. This applies equally to humans. Our evolutionary background makes it hard to identify with outsiders. We’ve evolved to hate our enemies, to ignore people we barely know, and to distrust anybody who doesn’t look like us. Even if we are largely cooperative within our communities, we become almost a different animal in our treatment of strangers.

Within a bottom-up framework, the focus is not so much on the highest levels of empathy, but rather on its simplest forms, and how these combine with increased cognition to produce more complex forms of empathy. How did this transformation take place? The evolution of empathy runs from shared emotions and intentions between individuals to a greater self/other distinction—that is, an “unblurring” of the lines between individuals. As a result, one’s own experience is distinguished from that of another person, even though at the same time we are vicariously affected by the other’s. This process culminates in a cognitive appraisal of the other’s behavior and situation: We adopt the other’s perspective.

Having descended from a long line of mothers who nursed, fed, cleaned, carried, comforted, and defended their young, we should not be surprised by gender differences in human empathy, such as those proposed to explain the disproportionate rate of boys affected by autism, which is marked by a lack of social communication skills.

Consolation is defined as friendly or reassuring behavior by a bystander toward a victim of aggression. For example, chimpanzee A attacks chimpanzee B, after which bystander C comes over and embraces or grooms B. Based on hundreds of such observations, we know that consolation occurs regularly and exceeds baseline levels of contact. In other words, it is a demonstrable tendency that probably reflects empathy, since the objective of the consoler seems to be to alleviate the distress of the other. In fact, the usual effect of this kind of behavior is that it stops screaming, yelping, and other signs of distress.

rhesus monkeys refused to pull a chain that delivered food to themselves if doing so gave a shock to a companion. One monkey stopped pulling the chain for 12 days after witnessing another monkey receive a shock. Those primates were literally starving themselves to avoid shocking another animal.

This capacity likely evolved because it served our ancestors’ survival in two ways. First, like every mammal, we need to be sensitive to the needs of our offspring. Second, our species depends on cooperation, which means that we do better if we are surrounded by healthy, capable group mates. Taking care of them is just a matter of enlightened self-interest.

people may have an inborn biological propensity to be more sensitive to social input, and still learn when, how, and where to use this ability from life experience.

There’s neuroscientifc studies thatshow that when people play games together and earn an award, there’s a greateractivation of their dopamine reward circuitry than when they earn that same awardon their own.

differentiate something called empathic concern from something called empathicdistress and what it turns out is that empathic concern is associated with all kindsof benefits people who experience empathic concern are more likely to help, they’rebetter at regulating their own emotions they’re more stable and socially functionalin life whereas people who experience empathic distress have other issues andstruggles that we can flesh out in later weeks. The interesting thing about thisbody of work is that it anticipates are next week of material which will be aboutcompassion and compassion is really what elevates empathy from the potential forempathic distress

So when we look at what happens inthe brain, when people are viewing images of other people in pain what we see is aspecific set of structures that systematically represent that state of being moved bythatso the activation is typically in the interior insula and the medial prefrontal corticesand the insula is important for representing visceral activation so once again yoursadness or your pain or your suffering causes me to get aroused something happensin my body in response to that and my midline activation is typically implicatedin being concerned or trying to understand what that means like what is it to mewhat is this feeling that I’m having in my body usually mean? And those are themechanisms that are involved in affective empathy. Cognitive empathy involvesa wider range of structures, distributed around the cerebral cortex and they’reinvolved in visual expertise and again a self referential knowledge, what is thisparticular moment mean related to my memories about the world or my historicknowledge. So there are separate structures separate systems that are involved inthese two different ways that we can learn to know other people.

Think of taking a yoga class or a dance class. If you had to do this with the teachersimply explaining step by step verbally what to do it would be much morechallenging than it is when the teacher actually demonstrates it physically andthat’s precisely because of your mirror neurons that are helping you simulate andrepresent that motion prior to actually trying to do it.

shown when you block ones ability tomimic a face a facial expression of somebody that’s in front of them by having them,say, bite on a pencil so they can’t use their facial muscles in a spontaneous way,they’re not as good at recognizing the expressions that they see.

When you especially resonate with someone else, the two of you are quite literally on the same wavelength, biologically. True connection is one of love’s bedrock prerequisites—and a prime reason that love is not unconditional. True connection is physical and unfolds in real time; it is neither abstract nor mediated. It requires a sensory and temporal co-presence of bodies.

found time andtime again if I have really rich patterns of friendships I feel less stress on a dailybasis I have lower levels of he stress hormone cortisol so its starting to affect ourstress profiles

and what we know is tight connections tofriends are one of the great determinants of happiness and health. The strongerthe networks of friends that we have the greater the happiness and well being weenjoy in just about every part of the world. We know that strong friendships areassociated with better health profiles.

influential theorizing that I want you to be mindful of of Shelley Taylor, showing thatour tendencies toward friendship and connection activate oxytocin and counteractthe responses of stress so we start to get a picture of why friendships matter.

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.

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.

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.

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.

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.

oxytocin doesn’t just bond us to mothers, lovers, and friends—it also seems to play a role in excluding others 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 narrow thinking that medications are the only way to control persistent pain,” Dr. Arnstein concluded, “has resulted in a lot of suffering.” Researchers have discovered a physiological basis for the warm glow that often seems to accompany giving. “The benefits of giving back are definitely biological,” says bioethicist Stephen G. Post, co-author of Why Good Things Happen to Good People. “Contemporary neuroscience has confirmed the connection between the physiological and psychological. We know now that the stress response, hormones, and even the immune system are impacted by, and impact, the pathways in the brain. MRI studies of the participants’ brains revealed that making a donation activated the mesolimbic pathway—the brain’s reward center.”