Kevin Sharpe, 'Science of the Soul'

Love and happiness represent two emotions lying at the heart of human existence. They come from our souls. Ask anyone what they most desire from life, and they will likely reply simply with ‘happiness.’ We go to great efforts to satisfy this desire: seeking out engaging and fulfilling occupations, choosing and decorating where we live for maximum comfort and contentment, filling our leisure time with enjoyable pursuits, and making lifestyle choices that we hope will make us happy. Much of our energy goes toward finding a suitable mate, someone with whom we can share our hopes, our fears, our desires, someone with whom we can attain utmost happiness. Once we have found our heart’s desire, many of us decide to strengthen and fulfill that union further by together creating and caring for children. Close loving relationships shared with our partners and, perhaps later, with our children represent one sure route to happiness for many of us.

The centrality or importance of an idea often becomes apparent from the effort we expend in trying to explain or account for it. So it is with love and happiness. These two emotions traditionally fall within the remit of spiritual explanation but, increasingly, they are becoming the focus of scientific scrutiny. With the recent growth of behavioral genetics, neurochemistry, and evolutionary psychology, a new window opens onto our behavioral, emotional, and social traits. Love and happiness capture the attention of the two most influential explanatory systems available to humanity: the scientific and the spiritual.

Tonight I will talk mostly about the science side of these aspects of our lives, and then touch on the implications of these studies for spirituality.

Happiness

Oh happy days, Oh happy days.
When Jesus washed all our sins away.

Those who find salvation are some of the happiest people around. At least so a band of popular belief suggests. Research supports it. Whether Jesus or anyone else saves us or not, most of us already feel happy and satisfied with life. Surveys of 1.1 million people from all over the globe say that 93 percent of people feel happy (which includes very happy, pretty happy, and moderately happy) as opposed to sad or neutral. In fact, most of us describe ourselves as ‘pretty happy.’ Holding to a particular or any spiritual belief doesn’t seem to matter, happiness-wise.

On what does happiness depend?

The Happiness ‘Set Range’

For each of us, our happiness fluctuates within a small range called a ‘set point’ or ‘set range’ that our genes largely determine. The set range represents a kind of preset value with which we are born and to which our level of happiness inevitably returns. This notion resembles the metabolic set range that some scientists claim governs our weight; no matter how dedicatedly we adhere to our diet, the body’s metabolism readjusts to maintain its preset weight. This could explain why some people find it so hard to shed excess pounds, while others are lucky enough to have figures like supermodels. Studies showing that body mass is 70 percent heritable lend credence to the metabolic set range. Some of us similarly always approach life full of hope and enthusiasm, while others seem permanently to experience the blues. Though we experience temporary mood swings, we soon readjust to our genetic set range for happiness in the same way as with our weight fluctuations.

Support for the genetic set range comes from a series of twin studies. Twins provide an excellent base from which to study the degree of heritability of behavioral traits because identical twins share identical genes whereas fraternal twins share genes as do ordinary siblings (roughly 50 percent). Take a particular characteristic and find out how often identical twins share it and how often fraternal twins do. The greater the difference between these two percentages, the greater the characteristic’s heritability and the smaller the role played by external or environmental factors.

Identical twins attain the same level of happiness 44 percent of the time, while fraternal twins reach the same level only 8 percent of the time. The main study on this asked 1,380 pairs of twins raised together to rate themselves on claims like, ‘I am just naturally cheerful,’ and, ‘My future looks very bright to me.’ Similar results emerge from a smaller previous study with twins separated in infancy and raised separately. This conclusion means the broad heritability of happiness is 40 to 50%, and that the variance in adult happiness is determined about equally by genetic factors and by the effects of experiences unique to each individual. Sex, age, race, and marital status of the twins have only a slight (2 percent) impact.

Heritability raises even higher for happiness in the long term. A study administered the same questionnaire to a subset of the twins five to ten years later and then performed cross-twin, cross-time calculations, comparing the score of one twin at 20 with his or her co-twin at 25 or 30. The correlation statistics show that the heritability of the stable component of happiness is about 80%. A twin’s self-report of well-being provides a good indicator of the state of the other twin. Thus, how you feel right now is about equally genetic and circumstantial, but how you will feel on average over the next ten years is 80% because of your genes.

With heritability this high, wealth, education, or social status say surprisingly little about a person’s happiness.

Happiness and the Ups and Downs of Life

Different types of research similarly show that a person’s level of happiness remains stable over many years. In a study of 5000 adults, people who felt happiest in 1973 showed up as relatively happy ten years later. Changes that we naturally associate with major emotional upheaval – like starting a new job, getting married, or moving house – make no difference to happiness levels; scores for people who had experienced these changes remained as stable as people whose situation stayed much the same.

More evidence supports this conclusion.

Consider Rose Marie Lajoie, a Michigan Lottery winner. She says: ‘If you are a negative person to start off, if you are a dull person to start off, you’ll be the same way [after winning the lottery].’ Momentous events alter our level of happiness for a short time – the 50 percent non-genetic variation in happiness over the short term allows for this – but we quickly adapt and so the long term set range remains unaltered. We all recognize that euphoric feeling when we attain something precious – the coveted job or the college degree, perhaps – yet the feeling doesn’t stay with us long. All too soon we forget and move on, our eyes firmly fixed on the next target. So many of us plan their lives for a distant goal; we believe that if we become a C.E.O. or win a gold medal, then our lives will rise out of humdrum ordinariness. This isn’t so. There’s a rush of glory and then it fades.

The sting of tragedy disperses equally as fast. Even quadriplegics and others with severe disabilities describe themselves as happy. In their more objective reports, they can remember more good than bad events in their lives, and say they experience more positive than negative emotions day to day. Reports from friends, family, and interviewer ratings corroborate these findings. A study of car accident victims in Michigan reports that, only three weeks after suffering a paralyzing spinal cord injury, victims feel happiness as the overriding emotion. Another study compares a sample of Illinois lottery winners, individuals who had suffered crippling accidents, and a control group that had escaped both fates. The lottery winners generally feel less happy than the control group, and that the disabled people feel much more happy than expected.

How long does it take for people to adapt to relatively minor events like gaining a promotion or losing a lover? Usually, the effect on a person’s mood is gone by three months, and there’s not a trace by six months. Expect the effect to have dispersed within a year.

For more serious events like divorce, bereavement, or unemployment, the effects can last longer, of course. This tends to indicate a clinical disease, such as depression, which overrides the customary set range. In these cases, the bad event in some sense continues to happen – there are reminders every day.

The ‘slings and arrows of outrageous fortune’ clearly influence mood, but long-term equilibration to life’s ups and downs is partly a function of the slings and arrows of genetic fortune.

The Biochemistry and Neurology of Well-Being

The genetic view of happiness has implications for our understanding of the cause of our feelings of well-being, because our genetic code translates directly into how our neurology (our nervous system) behaves.

We ought to direct our attention to two of the more than 300 known neurotransmitters, dopamine and serotonin. Dopamine acts as the brain’s chemical for pleasure. It’s what’s released after a good meal, a pleasant sexual experience or a hit of cocaine. Recreational drugs like amphetamines prove so popular because they belong to the same family as dopamine and produce similar effects: feelings of happiness, contentment, and satisfaction.

Serotonin is the brain’s ‘punishment chemical’; with its reduced activity, misery appears. Scientists associate lack of serotonin with depression, suicide, and anxiety, the symptoms of a modern malaise. Prozac and other SRIs prolong the action of serotonin produced by the brain.

Neurotransmitters like dopamine and serotonin work by passing information from the synapse or junction between a nerve cell and another nerve cell or a muscle. The nerve cell’s bulbous end releases them from storage when an electrical impulse moving along the nerve reaches it. They then cross the junction to dock at a receptor on the other nerve cell, like spacecraft docking at a space station, and either prompt or inhibit the impulses along the second cell. The first nerve cell reabsorbs excess neurotransmitters, but not necessarily all of them. Those that remain free-floating, according to biology, help create our happy or miserable states of being.

Genes carry the instructions for the construction of neurotransmitters, their receptor and reabsorption portals. They also impart information on such things as their storage and release rates. Hence, genes can influence the prevalence, scarcity, and activity of serotonin and dopamine, and, in turn, whatever behaviors and feelings these neurotransmitters induce. Researchers have found, for instance, that people who differ in the gene that produces part of the D4 dopamine receptor – the part that controls the amount of dopamine binding there – differ in a parallel way in their moods. People with the highest levels of dopamine report feeling the most positive. This is the first time there’s been a specific connection between a molecular genetic finding and people’s levels of happiness.

Some scientists think they have located the part of the brain that registers happiness and where the set-range mechanism works. One study shows that people with more activity on the left prefrontal area of the brain experience greater happiness, while those with greater activity on the right prefrontal area experience more negative emotions. People with the greatest right prefrontal activity suffer from clinical depression and claim that life holds no pleasure for them. Even very young children appear to fit the pattern: babies of ten months tend to cry less easily when separated from their mother for short periods if they exhibit more active left prefrontal lobes. Another study indicates that feelings of happiness, sadness, and disgust all co-occur with increased brain activity in the thalamus and medial prefrontal cortex. Greater activity near the ventral medial frontal cortex distinguishes happiness from sadness, while happiness correlates with significant increases in bilateral activity near the middle and posterior temporal cortex and hypothalamus. Spatially distributed brain regions participate in each emotion.

Attitudes for Happiness

Other sciences beyond behavioral genetics and neuroscience contribute to this discussion. Social psychology explores activities that activate our happiness: sharing in stellar sex or consuming delicious dinners, perhaps. Four character traits seem to make for happiness:

1. Happy people have high self-esteem; they like themselves. According to a Gallup poll, 85% of US residents voted having a good self-image or self-respect as very important, and 0% voted it unimportant. These kinds of feelings help cushion us against the demons of anxiety and depression, and so bolster our happiness levels.

2. Happy people feel optimistic; they exude hope and feel able to succeed at tasks they undertake. Increased optimism means better health, which in turn leads to greater happiness. A study of Harvard University graduates shows that those people who felt the most pessimistic in 1946 were the least healthy in 1980.

3. Happy people are extroverts; they feel self-confident and mix easily with others. Extroverts are more likely to marry, find good jobs, and make close friends. These achievements lead to greater satisfaction with life.

4. Happy people feel in control of their lives. Allowing prisoners, nursing home patients, and employees to make decisions about their environment and its running results in increases in happiness. Controlling our own time also leads to happiness. Happy people are punctual and efficient, while unhappy people postpone things and are inefficient. Good time management provides a sense of control.

The ‘happy farms’ scattered across the US provide commercial counterparts to psychological descriptions of what leads to happiness. Here you can learn about inner wisdom, self-confidence, personal empowerment, motivation, reconciliation with the past, and greater vitality – all for a substantial weekly sum. Our determination to find true happiness has turned it into a multi-million dollar industry.

Mihaly Csikszentmihalyi discusses another road to happiness in his book, Flow: The Psychology of Optimal Experience. He writes of when we find ourselves absorbed in an activity and time flies: then we experience flow. Life flows when we engage our skills and talents optimally, avoiding underchallenge (which results in boredom) and overchallenge (which results in stress). When in a state of flow, we feel happy, satisfied, a sense of meaning, purpose, and control. Csikszentmihalyi first observed this state when studying artists who spent hours absorbed in their work. They concentrated purely on their creation, toiling for the sake of the art alone, not for money, fame, or other extrinsic reward. Numerous other activities besides artistic creation can result in flow: climbing a mountain, writing a book, weaving a rug, playing tennis, for example. Any of us can experience flow, so long as a challenging activity absorbs us. We report more positive feelings when in this state than when we laze around, bored, doing nothing much. Flow promotes happiness.

Social psychology also tells us about things that fail to make us happy. Happiness doesn’t rely significantly on external factors: economic class, age, gender, education, or race. Wealth doesn’t correlate with happiness, except in the very poorest countries. Despite the fact that, compared with 1957, people in the US have twice as many cars per person – plus microwave ovens, color TVs, VCRs, air conditioners, answering machines, and $12 billion worth of new brand-name sneekers a year, they feel no happier now than in 1957; 35 percent declared themselves ‘very happy’ in 1957 compared to the slightly smaller figure of 32 percent nearly four decades later. Money doesn’t buy us happiness.

Happiness and Evolution

The science of evolutionary psychology aims to explain human goals, beliefs, and theories in Darwinian terms…at least in part. The urge to survive and reproduce determines even the ways in which we think, the ways in which our minds work. The point is this: Those proto-humans who believed in 2+2=4, rather than 2+2=5, survived and reproduced, and those who did not, did not. The belief that 2+2=4 proves advantageous for our survival, therefore we take it as true.

Evolutionary psychology has something to say about happiness too. Evolutionary psychologist, Donald Campbell, describes us as condemned ‘to live on a hedonic treadmill.’ We fanatically pursue happiness yet, no sooner do we reach one goal, than the satisfaction fades away and we commence reaching for the next rung on the ladder of pleasure. This, of course, restates the idea of a genetic set range for happiness. We feel ecstatic on gaining a pay rise, but soon find that our material situation feels little different from before. We no longer feel happy. Perhaps we can live the high life more frequently, but we soon get used to that. We want another rise. We’ve habituated and feel the need to strive once more.

In an evolutionary scheme, what adaptive advantage did seeking happiness bring to our forebears, if frustration and dissatisfaction constitute the net outcome? Maybe only those people who live in oppression and without hope of motivation have given up entirely on the search for happiness. Or, perhaps we are built to be effective animals, not happy ones. We’re designed to pursue happiness; and the attainment of Darwinian goals – sex, status, and so on – often brings happiness, at least for a while. Still, the frequent absence of happiness is what keeps us pursuing it, and thus makes us productive.

The search for happiness, therefore, plays the key role. From the point of view evolutionary psychology, our desire for pleasure keeps us on our toes. The activity expands our horizons, our resources, and our skills. Parents employ much the same catch-it-if-you-can psychology when encouraging their offspring to walk; brandishing a favorite toy lures the child into stepping toward it, moving the toy further away means that the child progresses a few steps nearer. As the toy recedes ever further, the child’s walking ability improves proportionally.

A limit blocks how far the pursuit of happiness benefits us, though, just as a limit prevents how far the child can chase the toy before keeling over. How much fitness is worth striving for? Ice Age people would have been wasting their time if they had fretted about their lack of camping stoves, penicillin, and hunting rifles, or if they had striven for them instead of better caves and spears. We need to decide what we can reasonably attain. We can gauge this in two ways: by noticing what others have attained and by noticing how well off we are at the moment. What others have attained provides an insight into what we might attain for ourselves. This kind of comparison gives rise to the ‘keeping up with the Joneses’ mentality: when Mrs. Smith glances over the fence and sees that Mrs. Jones has a glittering new Humvee, she feels she must have a vehicle just the same or better. We want what others have. The second way that helps us gauge what we can reasonably attain involves our taking stock of how well off we are. We can then aim to achieve just that little bit more, and more, and more....These two standards of comparison help ground evolutionary theory’s forecast that our reach should exceed our grasp, but not by much.

Christian Views on Happiness

Contemporary orthodox Christianity loses sight of the here and now, focusing instead on happiness lying someplace else – a land of original bliss and innocence (the Garden of Eden) or of future joy (Heaven, our eternal and happy home where we will see God face-to-face, or the Promised Land where we will find happiness and complete satisfaction). Christianity thinks of Heaven as destination and reward, succor and relief from earthly trials. It is an endless dynamic of joy. A friend with a staunch Roman Catholic upbringing talks of her constant sinning because she fails to say grace before every meal, pray every night, and attend church as often as possible. She feels she must overcome this tendency through acts of penance to achieve happiness in the afterlife.

Modern religious leaders like Robert Schuller prefer to focus on happiness in the present. He writes about this in his book, The Be Happy Attitudes: Eight Positive Attitudes that Can Transform your Life. Such charismatic and Pentecostal movements assume that the spiritual intends for happiness. Happiness is nearness to God. We move close to God through the emotionally high world of human togetherness, epitomized by hallelujah crying and hymn singing.

And today’s believers do stand out as prime examples of happy people. The highly spiritual declare themselves very happy at twice the rate of those with the lowest spiritual commitment, according to a recent Gallup survey. A study of 166,600 people in 14 countries demonstrates that happiness and satisfaction with life increase with frequency of attendance at worship services.

Modern religious thinkers propose that an active and committed spiritual life leads to happiness. To their eyes and to those of millions of contemporary Christians, the Bible paints a picture of a gracious and loving deity who desires everyone’s happiness. Happiness arises directly from God.

Conclusion

The several sciences that discuss human happiness include one common point of focus: happiness is a natural phenomenon. This naturalism takes several forms:

· a set range for happiness that our genes encode,

· neurotransmitters responsible for our states of well-being and misery,

· concrete activities (engaging in rewarding pastimes, or making lasting friendships) leading to joy, and

· the pursuit of happiness bringing adaptive advantages that aid our survival and reproduction.

Despite this apparent diversity of topics, the materialist focus shines through. Our biology directs us into our passionate love affair with happiness. No room appears to remain for a spiritual slant on happiness; objectivity replaces subjectivity and mysticism. Can naturalistic and spiritual accounts of happiness co-exist? Should we abandon one account in favor of the other? If so, which one? And why?

Many of us will instinctively feel that happiness must comprise more than biological drives and chemical activity. This sense may feel compelling and we should take our convictions seriously.

Love

A boy in school steals, cheats, fights, and lies. No matter what adults try, they cannot turn him into a responsible and loving boy. Teachers blame his family background; parents call for a special educational program; counselors work on building self-esteem. The established system considers outside intervention the cure. Does the problem lie outside or inside the boy?

The scientific search is on:

· ‘A natural chemical called oxytocin is found to underlie love,’ writes Robert Wright.

· In his book, Living with our Genes, Dean Hamer explains: ‘Everyone, gay or straight, feels the tug of genes involved with sex and love, from the sharp pangs of puberty, to the defining role of gender, and the fierce, protective feelings of a parent for a child.’

· A group of neuroscientists, social and behavioral scientists, clinical psychologists, biological psychiatrists, and psychoanalysts gathered at a symposium – like several other recent gatherings – to discuss the question: ‘Is there a neurobiology of love?’

Love emerges from the emotional closet and scientists struggle to isolate and understand the physiological processes underlying our expressions of romance, responsibility, and caring.

Oxytocin and Vasopressin

Inside our brains lies a hypothalamus, the organ that controls ‘primitive’ behaviors such as sex, aggression, and feeding. It produces the hormones oxytocin and vasopressin, which then pass through a stalk down to the posterior pituitary gland at the base of the brain for storage and secretion. Both of these biochemicals evolved from the primordial hormone vasatocin, which still endures in the lower vertebrates such as fish. Both share a similar molecular structure, differing in only two out of their nine amino acids, the building blocks of proteins. When released into the body, they bind to specific targets called receptors located in the brain and elsewhere, like keys fitting into locks. The receptors then affect other body parts and, finally, behavior.

Medicine has long known the effects of oxytocin on the female reproductive system. It naturally stimulates contractions in the uterus right through the birth process by locking onto specific receptors in the muscles of the uterus, causing them to tighten. Not surprisingly, the name ‘oxytocin’ derives from the Greek for ‘swift birth.’ Obstetricians inject a synthetic form of it to arouse contractions when labor flags. It also helps control excessive bleeding after delivery of the infant. It prompts the mother’s mammary glands to release milk within seconds after her baby begins to suckle. So susceptible is oxytocin release to emotional influences, even the cry of a hungry baby can prematurely stimulate milk let-down. Oxytocin also plays a physiological role in highly emotionally charged activities like coitus, nipple eroticism, and female sexual responsiveness.

Research continues into the source and functions of oxytocin. A study on oxytocin’s role in prompting labor in animals shows that the uterus, rather than the hypothalamus, produces oxytocin for this purpose. Similar evidence occurs in humans: women who commence labor naturally have much higher placental concentrations of RNA (which governs production of oxytocin) than do women who give birth by caesarean section before natural labor begins.

Biochemists have developed several synthetic oxytocin ‘antagonists.’ These copycat proteins chemically resemble oxytocin and bind to the appropriate receptors, blocking out the real oxytocin molecules and thus the effects normally induced by the receptors. For those mothers who experience premature labor, injecting an oxytocin antagonist is very good at suppressing contractions.

Oxytocin’s companion hormone, vasopressin, also plays a key role: it maintains a constant volume of water in our bodies and regulates to within narrow limits the concentration of dissolved substances in the fluids outside our body cells. Many specifically male functions of certain animals – such as marking territorial boundaries with scent – involve vasopressin, giving it a reputation as the ‘real man’s’ molecule.

Recent research with vasopressin and oxytocin begins to inculcate fields other than medicine. Oxytocin receptors may play a much larger role in social behavior than researchers previously thought. The formation of social bonds between mothers and their children seem to be linked to the release of oxytocin. Could it be the hormone of ‘motherly love’? Physiological changes might prepare an expectant mother, arming her with the psychological tools she needs for her unfamiliar new role. Further, the secretion of oxytocin influences our sexual as well as our maternal bonds.

The research gains momentum. A virgin female rat in the laboratory, when first presented with pups, usually ignores them, is frightened of them, or eats them. She will tolerate them only when they are introduced to her many times over several days. Then she may even care for the youngsters by licking them, retrieving them when they stray from her side, and crouching over them protectively…just what we expect from a responsible mother. A pregnant rat, on the other hand, responds to pups caringly within minutes, even before delivery of her own. When virgin female rats are injected with blood from rats that had just given birth, they nurture the pups in significantly less time. Could something in the blood elicit a maternal response? Could that something be oxytocin? Further, parent rats can mistreat their children when injected with antagonists to block their oxytocin receptors.

Vole Research

Voles are small, brown, nondescript mammals of the genus Microtus, and which live under seeds and grasses. Members of one species – the prairie vole – put us humans to shame. They share elaborate systems of burrows and feeding tunnels and, unlike most rodents, males and females form long-lasting bonds, raising their young together. On the other hand, montane (or mountain) voles are home wreckers par excellence. They occupy separate burrows and avoid each other except to mate…which they do often and indiscriminately. Mother montane voles usually abandon their pups 16 days after birth and fathers never see their offspring. When a predator plucks a youngster from the nest, it neither calls for help nor surges with stress-related hormones. Why, in comparison with their prairie cousins, do the high-meadow montane voles lack family values and behave so asocially?

Do these species differ with respect to central pathways for oxytocin or vasopressin? The species do differ in the neural distribution of receptors for both hormones as much as they differ in behavior. Prairie voles have three times the number of oxytocin receptors in their prelimbic cortex – and seven times more in their nucleus accumbens – than do montane voles. Yet receptors for other unrelated hormones match across the species. Might the differences in receptor distribution relate to the differences in social behavior?

Making this even more interesting is the fact that, during the brief period in which female montane voles nurse their young, the number of their oxytocin receptors surges, matching those of the female prairie vole. Could distribution patterns of oxytocin receptors account for social characteristics of monogamy and childcare? Probably yes. This is evidence that oxytocin receptors may be very important for the so-called affiliative behaviors that make animals open to forming and continuing social attachments.

As soon as the female prairie vole becomes sexually active, she and a male will copulate repeatedly, more than 50 times in over 36-48 hours. She becomes much more socially exclusive after this sexual frenzy, preferring her mate to unfamiliar males. Mating seems to instill long-term pair bonding. Copulation causes the release of oxytocin in a number of small mammals; might this be the critical factor in developing the female prairie vole’s social preferences and fidelity? A female prairie vole rapidly forms a preference for a male if exposed to oxytocin for, say, six hours. However, when administered with an antagonist to block the oxytocin receptors, oxytocin ceases its social effect. These results suggest that oxytocin’s action within the brain may be one of the physiological events that lead to the formation of monogamous pairs.

Other Research with Mothers and Offspring

Studies of domestic sheep strengthen the case for oxytocin’s social role. As a lamb moves down its mother’s birth canal, it stimulates nerves that trigger the release of oxytocin. Only with oxytocin present at birth, or injected so it reaches the brain at the same time as mother ewe meets her newborn, will she bond with her offspring. High levels of oxytocin also occur in her milk. She rejects her lamb if something blocks oxytocin’s release. Perhaps the lamb’s oxytocin ingestion helps forge a mutual attachment.

Further evidence for a link between oxytocin and mother-infant attachment emerges. A human infant’s suckling leads to an oxytocin-mediated increase in blood flowing to the skin covering the mother’s mammary gland. A warm nipple may encourage the offspring’s attachment by inducing physiological effects of a calming and nurturing nature.

When 15-day-old rats associate an odor with their mother, they approach the smell more quickly and spend more time with it than when they fail to make a maternal association, provided they make the association after the administration of oxytocin. Administration of an oxytocin antagonist prior to association fails to produce the attachment effect.

However, more recent data seem to fly in the face of the growing results about oxytocin. Scientists have created genetically deficient ‘knockout’ mice that lack a working gene for oxytocin. Yet these mice can still mate, give birth, and display normal maternal behavior. It’s startling to find out that mice that have no oxytocin whatsoever seem to have pretty normal reproductive behavior.

Knockout mice do differ in significant ways from normal mice. For a start, they can’t nurse their young unless artificially injected with oxytocin. The milk is there; they just don’t let it down in response to suckling. They also display differences in social behavior, mostly centering around aggression and social investigation. The knockout mice don’t seem to investigate other mice as much. Knockout pups also demonstrate a decreased tendency to emit ultrasonic isolation calls when separated from their mother and littermates. Perhaps these pups fail to form social attachments early in life, and are therefore not distressed by the separation. Whatever the story with physiology, exposure to oxytocin still seems to influences social behavior.

Perhaps it shouldn’t surprise us that oxytocin-deficient mice can still reproduce and care for their young. Reproduction is just too important to have one mechanism for ensuring giving birth; there’s bound to be redundancy in the system.

There is another explanation. The evidence derived from knockout mice contradicts several rat (and sheep) studies that say oxytocin does induce maternal behavior. But rats and mice differ importantly. Virgin rats do not display maternal behavior in that they ignore pups and can commit infanticide, yet, just before birth, a striking shift occurs: they become driven, relentlessly building nests and retrieving, licking, and protecting pups. Infusions of oxytocin facilitate the shift, but the administration of oxytocin receptor antagonists blocks it. Virgin female laboratory mice, by contrast, exhibit full maternal behavior on first exposure to pups. Since there’s no shift in maternal behavior occurring in laboratory mice when they give birth, it’s not surprising that oxytocin-deficient mice show normal maternal behavior. We must be careful in making generalizations regarding the relationship between oxytocin and specific behaviors. This kind of explanation suggests that oxytocin induces maternal care in certain species, but may control milk ejection in many more. The role of oxytocin in the regulation of social behaviors must be considered on a species-by-species basis.

Research with Males

What about males’ sexual and parental behavior?

After the initial sexual bout, a male prairie vole prefers his mate and ferociously guards against rivals, even in her absence. A male isolated from females and injected with vasopressin becomes aggressive and attacks other males. (Females respond little to vasopressin.) If exposed to a female and injected with vasopressin, a male develops a preference for her even if they do not mate. Administering a vasopressin antagonist to a male ready to mate doesn’t prevent repeated and intense copulation, though afterwards he doesn’t fend off intruders or prefer his partner. An oxytocin antagonist, on the other hand, alters neither the male’s mate preference nor his guarding behavior. Vasopressin also increases (and a vasopressin antagonist decreases) the amount of time a male spends with his pups, which he would typically and naturally do by retrieving them and huddling over them.

Administering vasopressin to the polygynous, non-parental male montane vole induces quite different effects: it increases his self-grooming, but has no effect on his behavior toward either his mate or his offspring. The two species appear to express love in different ways: the prairie vole directs affection toward his family, while the montane vole directs it toward himself. Difference in the distribution of vasopressin receptors between the two species may again account for the difference in social behavior.

Many biologists believe that the kind of paternal care exhibited by the prairie vole anchors male monogamy. Many believe that vasopressin (in conjunction with its receptors) plays a part in male sexual and parental behavior. Vasopressin may have a more general role in eliciting parental care and defensive behavior with respect to self and family. Vasopressin may be sufficient for male pair bonding.

While oxytocin encourages social contact, vasopressin compels the male’s antisocial, guarding behavior after copulation. These hormones – their behavioral and cellular functions – counter each other in some circumstances. Perhaps oxytocin blocks the unfriendliness induced by vasopressin. On the other hand, no matter what the mechanisms, vasopressin and oxytocin together help determine for many species if a pair bond, nurture and care for their young, and defend their family. Vasopressin and oxytocin seem crucial for pair bonding, eliciting parental care and nurturing, and defending the family. Monogamy and polygyny therefore appear to express the net outcome of what happens when oxytocin and vasopressin activate different circuits in the brain

Humans

We’re all dying to know about humans. Does the love we display toward our partners and kids translate into talk about neurochemicals?

The human brain manufactures vasopressin and oxytocin molecules that bind to receptors there. So they exist and work in our brains. Our forebrain, in particular, contains many oxytocin receptors. Further, though vasopressin and oxytocin are large molecules and do not readily penetrate the blood-brain barrier, they exist in larger-than-normal quantities in the brain when hard at work elsewhere in the body. They could, in principle, influence our social behavior.

Much of the maternal behavior displayed by an expectant mother arises from hormonal changes that her system induces. After birth, it stems from sensory stimulation and interaction with her child. A sensitive period for mother-infant bonding occurs just an hour after birth, when the mother’s oxytocin level rises markedly. Could oxytocin act as a catalyst for the bonding mechanism?

Lactation is also accompanied by behavioral changes which may be linked to central actions of oxytocin. Not only do women report feeling relaxed and sedated during nursing, but they also feel calmer and more socially interactive than do non-pregnant, non-breastfeeding women of a similar age. Women’s degree of calm correlates with their oxytocin levels. Further, women who give birth via caesarean section don’t report the kind of personality changes noted by those who give birth naturally. Could the oxytocin released at (natural) birth and feeding enhance social and maternal feelings, and so facilitate bonding between mother and child?

One study on male humans shows that vasopressin peaks in the bloodstream during sexual arousal, and oxytocin at orgasm. In both female and male humans, oxytocin levels rise dramatically during sex. Perhaps this promotes the feelings of romance and infatuation that we associate with love making.

We do share, it therefore seems, many physiological responses with other animals, but the important question is whether we share similar social responses…and whether oxytocin and vasopressin promote them. Do vasopressin and oxytocin provide the chemistry for human attachment?

Researchers exercise caution. Though receptors for both oxytocin and vasopressin lie in the human brain, their distribution pattern neither resembles that of the monogamous prairie vole nor that of the promiscuous montane vole. Perhaps we humans reside in a half-way house between monogamy and promiscuity. Few of us nowadays settle down with our first sexual partner and, even when in a stable relationship, our eyes rove and we appreciate the attractiveness of others. Studies with non-human primates (squirrel monkeys) show that increases of oxytocin and vasopressin in the brain do influence social interaction.

We actually know very little about the hormonal basis of social attachment in our own species. In large-brained primates like us, the effects of oxytocin and vasopressin are undoubtedly mediated – and perhaps inhibited – by many other factors, especially by the complex activities of our enormous cerebral cortex.

Conclusion

It’s tempting to dub oxytocin the ‘love molecule,’ but objectively establishing a causal association between oxytocin and love proves difficult. Too many variables confront the research. The roles of vasopressin and oxytocin are also difficult to document, even in animals. We clearly need to exercise caution when extrapolating data derived from animal or limited human studies. Many questions remain unexplored or only partly explored.

Even so, the research does show a biological rootedness to love for humans as well as animals, whatever else it may involve. Social bonds possess a biology. Love is in part a physical trait derived from evolution. Parental, filial, and sexual love happen with oxytocin and vasopressin, which promote the behaviors and symptoms of loving. When people love this way, these chemicals occur in their bodies in larger-than-normal amounts; love functions with them.

How do these scientific findings relate to spiritual love? According to most spiritual traditions, we possess the power to choose whether to love or not. Jesus urged us to love our neighbors. How much is free will involved in loving? We sometimes love despite ourselves; not many parents remain angry for long with their practical joker offspring. Can we decide to love, and do so, even if this means the decision prompts the release of hormones? This asks a crucial question. The involuntary release of oxytocin serves well the survival of our offspring, and with them, our genes. Could such vital functions depend on our whims alone?

What of divine love? The New Testament talks about God as love. Do oxytocin and vasopressin drive God’s love and concern for us? Must God embody hormones and biochemicals in the same way as do human beings?

Only with answers to the likes of these questions can the reconciliation of scientific and spiritual understandings of love commence.

Reconciling the Spiritual and Scientific Accounts

The conflicts between the spiritual and scientific accounts of love and happiness run quite similarly, but I will focus here on that involving love because, for one thing, it strikes more at the heart of Christian belief than does the issue over happiness. It relates more, we may think, to the soul.

One response to the conflict I call ‘Let’s-Have-’Em-Both.’ ‘All right,’ its adherents might say, ‘we accept that when we display love, biochemicals underlie our behavior. But God’s love? God is a spiritual being, not a complex of chemicals. God is love, some other kind of non-physical love.’ This sort of response hits the nail on the head, of course. It doesn’t rescue the idea of spiritual love, however. How can two such different notions of love exist? Why have we always treated divine and human love as similar? Can we reconcile spiritual and biochemical love? To suggest – as such respondents might do – that God evolved us to have similar qualities to him, invokes divine intervention into evolution with its inherently random mechanism of genetic variation. It overrides the billions of years of evolution necessary to produce the love of human beings. Why would God choose such a means to produce something that already existed? Answering questions and objections such as these requires that we radically rework our conception of God and of God’s relationship with us and the universe.

Such critics may also spy a second loophole. ‘What about agape, the Platonic love which we should show toward our fellow beings?’ they might ask. ‘None of the scientific research indicates that love extending outside the family circle stems from oxytocin or vasopressin.’ True, but evolutionary theory does suggest that altruism springs from our genes. Our genes push us to behave altruistically. By helping others, we ensure an easier ride for ourselves, so giving those same genes a better chance to propagate themselves via our offspring.

Whichever way we look at it, we can’t get away from our biology. Then the biochemical account must clash with traditional accounts of the spiritual nature of love. We’re left with an unloving conflagration. A way forward does exist. A way that recognizes the value of both accounts.

A way that faces the problems head on. It means that we must ask difficult questions. Is love a choice or an involuntary action? How does divine love relate to human love? The task of reconstructing our notion of God and of God’s loving relationship toward us is daunting. These endeavors, though, will enrich our knowledge and coax science and spiritual thought toward a new era of mutual respect and understanding. For such gains, a challenge and a rough ride seem a small price to pay.

[A book of mine on this subject is coming out in June: Has Science Displaced the Soul? Debating Love and Happiness. It contains the reference information for the passages above taken from other sources. Many thanks to Rebecca Bryant, co-writer of the book.]