by Ben Slotznick

Do bio-chemical processes form the basis of cooperation? Do they cause social bonding? Or generosity? Or trust? What are the implications of neuroscience for voluntary associations and fundraising? Research in the disparate fields of neuropsychology, experimental economics, and evolutionary biology, has been investigating some of these issues. There are intriguing results as well as questionable ones, all with tantalizing implications. Cooperative social behavior appears mediated at least in part by bio-chemical processes – though the extent is uncertain. Aspects of pro-social behavior appear innate – and others learned through bio-chemical reinforcement, both pleasurable and possibly addictive because of those same neural pathways. Facets of less-social behavior present similarly. Though portions of the scientific research remain problematic, enough is known to start placing some bets. Let’s start with a shaggy dog story.

Oxytocin and the monogamous vole

But first a short digression. Oxytocin is a peptide hormone found in humans and mammals. Since the 1950s, it has been known to be involved in uterine contraction during childbirth as well as lactation, and mother-child bonding. However, it is produced in both men and women and appears to be involved in both male and female orgasm. More recent research on rodents, has primed interest in the effect of oxytocin and additional peptides on other forms of non-kin social bonding.

Consider prairie voles, small monogamous mouse-like rodents found in middle America. Oxytocin and a related peptide named vasopressin are integral to the prairie voles’ rare marital fidelity – rare, that is, among voles and other mammals. The prairie voles’ promiscuous cousins, the montane voles and field mice (i.e. meadow voles), have neither as many oxytocin receptors nor as long vasopressin ones, nor in the same place. (In prairie voles, these receptors are located in the brain’s dopamine-mediated reward pathway.) The hormonal effects have been studied extensively and invasively, with hormone injection, genetic manipulation, and cell receptor suppression. The causal relationships are clear and accepted. As one of the original investigators Thomas Insel of Emory University has said, “When a monogamous vole mates, it is as if it got a hit of cocaine. The vole becomes addicted to whomever he was mating with.”

For the past 15 or so years, scientists have been investigating the extent to which effects of oxytocin, vasopressin, and other hormonal neurotransmitters, are involved in various types of social behavior among other species – including evolutionary biologists studying the domestication of dogs.

A dog walks into a room … It spends thirty minutes exchanging loving gazes with its seated master. Afterwards urine samples are taken of both dog and master. Both, have increased levels of oxytocin.

Amazing. A bio-chemical is implicated not just in sexual attraction between mates and kinship ties with offspring, but social attachments of all kinds – even cross-species ones!

Problematic aspects of research on people

Ethical concerns make it hard to study these bio-chemical processes in humans. You can’t just inject chemicals into people’s brains. You can’t destroy the neuron receptors in their brains either. And you can’t genetically engineer them. Instead, researchers have employed less direct approaches, each of which has its own limitations.

Perhaps it’s best to refer the reader to an article seriously questioning a decade of research on oxytocin effects: Nave G., Camerer C., McCullough M., “Does Oxytocin increase trust in humans? Critical review of research,” Perspectives on Psychological Science, 10.6 (2015): 772-789, online at Although their meta-analysis does not support research results linking oxytocin to trust, nonetheless, these authors conclude:

“Our review does not necessarily imply that true discoveries are not to be found in [oxytocin] research, and given the animal literature, it seems likely that [oxytocin] plays a role in the regulation of some social behaviors that are homologous across humans and other species.”

In fact, more recently (2016), two of these authors (Nave and Camerer) collaborated on a study which found vasopressin to increase human cooperative behavior: Brunnlieb, C., Nave, G., Camerer, C., Vogt, B., Munte, T., Heldmann, M. “Vasopressin increases human cooperative behavior by reducing aversion to social risk,” Proceedings of the National Academy of Science, The nascent and still uncertain state of the art is chronicled by Crockett, M. and Fehr, E. in “Pharmacology of Economic and Social Decision Making”, Chapter 14 of Neuroeconomics, Decision Making and the Brain, 2nd Edition (2014), edited by Glimcher and Fehr.

A chemical stew

Bio-chemical neurotransmitters implicated in cooperative behavior include oxytocin and vasopressin, serotonin and dopamine, adrenaline and cortisol, as well as testosterone. Some interfere with others; some reinforce or complement others. It’s an understatement to say their interactions are not fully understood.

Here is where I (as a lay person) am willing to place some bets: pro-social cooperative behavior is caused through the work of biochemical neurotransmitters such as these. So is competitive and status-seeking behavior. Sometimes these work together, and sometimes at cross-purposes. These bio-chemicals also effect behavior focused on in-group loyalty and out-group disparagement and competition.

When people do stuff together, aspects of the social-environment trigger neurochemical processes in each group member, bathing neural receptors with a potpourri of these chemical neuromodulators. The bio-chemicals affect behavior and decision making, but they can also feel good. Yes, they produce a natural bio-chemical high. Like prairie voles, people can get oxytocin highs. They also get adrenaline highs, dopamine highs, and testosterone highs. The sensations can be addictive and people seek them out. In all likelihood, this is much of what makes us social animals.

Perhaps it will be instructive to consider in what situations and under what stimuli researchers have sometimes found the human body to produce these bio-chemicals, and what kinds of behaviors have been sometimes found to be induced by them. Ongoing and future research is likely to qualify aspects reported below, or even refute some particular findings. However, I’d bet that the general import is likely to be confirmed.

What causes the body to produce oxytocin?

Oxytocin release can be induced by sex, massage, or just a hug – that is, a warm touch when it is welcome and appropriate. Petting a dog works … and much more. For women, nipple stimulation by a baby induces oxytocin in her breast which causes milk to flow, but just as importantly, oxytocin is also induced when a mother sees a baby, hears a baby cry, or even smells one.

These latter responses may be “learned” ones, because in addition to oxytocin, a mother’s body produces the neurotransmitters serotonin and dopamine. The body not only perceives this hormonal cocktail as pleasurable, but neural pathways learn that this social-sensory mix gives pleasure. This sort of imprinting is a biologically learned response to oxytocin which affects different people differently. Adults who were abused as children do not appear to have the same oxytocin responses as others.

Oxytocin release does not require touch. Group rituals such as singing, marching, and dancing – whether religious, tribal, or secular – can induce oxytocin production. So does participation in sports teams, perhaps even watching them with others. Religious services, even with minimal ritual such as at a Quaker meeting. And weddings. Not just the bride and groom, but the whole wedding party gets a jolt of oxytocin – and proportional to their connectedness to the bride and groom at the center of the ceremony. (Parents get more pumped than distant cousins.)

Sharing a meal and other face-to-face interactions can produce these effects. Even as attenuated a personal interaction as using social media can produce oxytocin, though neural engagement is higher when people interact face-to-face than for text or video. And of course, the amount of oxytocin increase appears related to how close you are to the person with whom you are connecting online.

Doing stuff together often inundates neurons with oxytocin.

Solitary (but empathic) endeavors can even be effective in stimulating oxytocin: meditating (though some forms may produce more oxytocin than others), watching emotional videos, experiencing effective storytelling and compelling narrative.

Moderate stress, teamwork, and team competition can produce both adrenaline and oxytocin. But actions often disparaged as mere social niceties provide oxytocin’s real kicker:

Being thanked – or praised.
Being trusted. Receiving a gift.
Being told you are loved – and telling people you love them.
Helping others – even strangers far away.

Whether this hormone’s generation is inbred or learned, the effects of oxytocin take place almost immediately, without conscious control or awareness. The chemical oxytocin itself is short-lived in the body, fading after about 3 minutes. However, the empathic response lasts for about half an hour. And what are these empathic responses?

What does oxytocin do?

Among voles, oxytocin not only causes monogamous bonding and tolerance of one’s own offspring, but also tolerance of neighbors (crowding) in a cage or colony. It increases cooperative behaviors like food sharing and can cause mothers to nurture offspring not their own.

Among people, oxytocin increases the ability to recognize social cues and understand what another is feeling. It decreases chronic stress, slows breathing and lowers heart rate. However, the pro-social effects may be most salient. Oxytocin may increase generosity (where there is some personal bonding) as well as reciprocity of giving (proportional to the oxytocin release). It can strengthen in-group feeling and willingness to sacrifice for the group, along with increased hostility to any out-group. It can boost envy and gloating, especially between groups. But it strengthens in-group trust.

Oxytocin can apparently cause people to act more kindly, more generously, more cooperatively, and more caringly — especially to colleagues but sometimes to strangers as well.

What about oxytocin’s companions?

Oxytocin does not work its “magic” alone. The chemical’s effects are both amplified by and compete with those of other hormones and neurotransmitters. The exact way they interact is not fully understood, however, enough is known about them for a useful sketch.

We’ve already mentioned that dopamine and serotonin are involved in learning and reinforcing learning. Dopamine is also involved in aversion and alerting events, as well as reward-motivated behavior and addiction. Vasopressin is another peptide neurotransmitter that in prairie voles contributes to their monogamy with (among other things) guard and defend behavior. In laboratory studies of people, it has been shown to increase “risky” cooperative behavior. (Risky in the sense that generosity or trust might not be reciprocated.)

We all know adrenaline as the “fight or flight” hormone. But if the adrenaline producing stress is extended, cortisol (another hormone) will also be produced. Moderate amounts of adrenaline (also known as epinephrine) can stimulate the brain to produce oxytocin, but higher amounts of adrenaline (or cortisol) will inhibit the release of oxytocin.

Testosterone can interfere with the release of oxytocin, and inhibit the binding of oxytocin to its receptors. The higher the testosterone, the more the oxytocin response is blocked, the less empathy the person experiences. Testosterone is implicated in the drive to win – whether in athletic or other contests, and whether the contestant is a man or woman. Nonetheless, team members in sports (and undoubtedly other team competition) produce both testosterone and oxytocin. After all, the team cannot win without cooperating with each other.

By itself, testosterone is associated with distrustful behaviors and aggression, as well as the drive for social status. It can promote risky behavior and thereby impede one’s judgment at the same time that dopamine can make this reckless behavior feel good. This helps explain why some people who are promoted act aggressively overconfident and entitled – a phenomenon sometimes called “the winner’s curse”.

Testosterone and oxytocin are present in both men and women – though men tend to produce more of the former and women of the latter. But every situation produces different responses. A man may normally have ten times as much testosterone as a woman, and women may usually produce more or be affected more by oxytocin than men, but nonetheless in laboratory studies of interpersonal cooperative behavior, sometimes a woman in the group will have the highest testosterone level.

Interestingly, though testosterone is not a social bonding agent, it stimulates enforcement or punishment behavior to enforce social norms, even if the act of punishing is “costly” to the enforcer. (In laboratory studies, costly punishment apparently produces dopamine rewards – that is, punishing others feels good.)

What does this teach us?

Bio-chemical processes form the basis of cooperation and social bonding in ways that are still being discovered. However, the implications of continuing neuroscience research for voluntary associations and fundraising are far-reaching.

Volunteers and donors are not compensated with money. But they are “paid” in jolts of dopamine, oxytocin, and other neurotransmitters. Sure, volunteering and giving bring other benefits – and reaching organization goals may yield a squirt of testosterone. Rivalries with other organizations can establish friendly in-group and out-group demarcations fueled by neuro-modulated processes that buttress in-group loyalty. Still … the reliable payoff is a bio-chemical high. Learn how to provide it, or lose your volunteers and donors.

For a New York Times article on the dogs and oxytocin research see: Another popularization of the research is in the Smithsonian: and the original article in Science: The Thomas Insel quote can be found at

Paul Glimcher and Ernst Fehr’s textbook, Neuroeconomics, Decision Making and the Brain, 2nd Edition (2014) can be found at

For extensive (though questioned) information about some of the experimental results concerning oxytocin and testosterone read Paul Zak, Moral Markets: The Critical Role of Values in the Economy (2008),; The Moral Molecule: How Trust Works (2012),, and Trust Factor: The Science of Creating High-Performance Companies (2017), More Zak references can be found at His popular TED talk is at