Listening to Paul Zak extol the virtues of oxytocin, the "love
hormone", is like hearing a preacher sing the praises of the Promised
Land. His idea of a harmonious oxytocin-fuelled society is so seductive
you find yourself almost praying it were true. At the same time, you
cannot help but wonder if it might be an illusion.
Oxytocin is
best known for its use in inducing labour. However, according to Zak,
the director of the Centre for Neuroeconomics at Claremont Graduate
University, California, it is also the "social glue" that binds
families, communities, and societies, and fosters trust between
strangers.
To illustrate his point, at a recent appearance at TED
Edinburgh, Zak spritzed the backstage staff with oxytocin, prompting a
spontaneous outbreak of group hugging. Indeed, such is Zak's faith in
the bonding hormone that his licence plate reads "oxytosn". When he
texts me to agree a time for our interview, the message reads "From Dr
Love's iPhone".
When we finally speak, Zak tells me that "oxytocin
is primarily a molecule of social connection. It affects every aspect
of social and economic life, from who we choose to make investment
decisions on our behalf to how much money we donate to charity. Oxytocin
tells us when to trust and when to remain wary, when to give and when
to hold back."
But of all Zak's claims, perhaps the one with the
most profound social and economic implications, if true, is his
assertion that oxytocin is the "essence of empathy". Indeed, Zak
believes that his research provides a scientific basis for Scottish
Enlightenment thinker Adam Smith's insight that humans are essentially
"other-regarding" creatures, imbued at birth with a capacity for "fellow
feeling" ("Even the greatest ruffian," Smith wrote in 1759, "is not
entirely without it.")
"It's the ultimate moral molecule," says Zak, who describes himself as a "born-again Smithian".
In
a summer punctuated by the horrific massacre in Norway and the shocking
scenes of destruction and looting in London and other British cities,
that claim will strike many as optimistic. But Zak goes further, arguing
that many of the social and political issues that currently seem so
intractable could be solved if only we could find a way of raising
people's basal levels of oxytocin.
As has been demonstrated at
Zak's lab in California, one way to achieve this is by getting
volunteers to inhale on an oxytocin nasal spray. But trust can also be
engendered by less invasive techniques, such as a 15-minute massage or
by logging on to social media – practices that Zak has shown also
elevate blood oxytocin levels; on a society-wide level, he argues, a
similar effect could be achieved by reducing disparities in income,
investing in education, and promoting greater freedom and opportunity.
The
key, he says, is to kickstart a brain circuit called HOME (human
oxytocin-mediated empathy). But can it really be that simple? As the
London riots demonstrated, bonding with strangers and trusting the
instincts of the herd can lead just as easily to bad behaviour as good.
Besides, what does Zak's research tell us that we don't already know: if
you're kind to strangers, then your kindness will be reciprocated?
Isn't that the message of every great world religion from Christianity
to Buddhism?
"We don't need the glamour of
neuroscience to tell us that Smith's observations about human nature are correct," argues Raymond Tallis, the author of
Aping Mankind: Neuromania, Darwinitis and the Misrepresentation of Humanity.
"What is missing in this research is the sense that economic decisions
and trust are based on one's interactions at the whole person and the
whole community level. The brain is just the middle man."
Oxytocin,
an extract from the human posterior pituitary gland, was discovered in
1909 when the British pharmacologist Sir Henry H Dale found it could
contract the uterus of a pregnant cat. He named the extract oxytocin,
from the Greek for "quick" and "birth". Within two years, doctors were
using oxytocin to bring on childbirth contractions. Dale later
discovered that oxytocin stimulated the release, or let-down, of
mother's milk by contracting the smooth-muscle cells around the mammary
glands.
Today, synthetic oxytocin, also called Pitocin or
Syntocinon, is often used to induce labour and to help new mothers who
have trouble with milk let-down. Oxytocin is also given to women just
after birth to prevent postpartum haemorrhage.
By the 1970s,
scientists had realised that oxytocin was also a neurotransmitter that
acted on the limbic system, the brain's emotional centre. The
game-changing insight, however, came from animal studies at the
University of Maryland showing that oxytocin played an important role in
fostering bonding and monogamous behaviour in prairie voles. In
addition, oxytocin has been shown to facilitate nurturing behaviour in
mice and rats: when oxytocin was blocked, the rodents stopped caring for
their young and displayed signs of "social amnesia".
When Paul
Zak, a mathematician and economist by training, stumbled upon this
research in the 1990s he had an "aha" moment: the animal studies seemed
to describe emerging behaviours of trust and cooperation seen in humans.
Like others in his profession, he had grown frustrated with classical
economic models that assumed that humans were rational actors who always
sought to maximise their individual gains. In his experience, this was
not how most people made decisions. He set out to replicate the animal
experiments on volunteers engaged in monetary games designed to elicit
trust, and then tested their blood for oxytocin. He wondered if the
human subjects would show a similar spike in oxytocin?
Shortly
after being granted tenure in 2001, Zak told the dean at Claremont that
he wouldn't be publishing for a while but instead had acquired a
centrifuge and cold freezer for storing blood products. The dean was
sceptical. "He told me that I was doing 'vampire economics'," recalls
Zak.
There are many variations of the "trust game" but the basic
idea is that a person (player one) is given some money and told to send a
portion of it to a second person (player two), who has a one-off choice
to either accept or reject the proposal. If player two rejects, neither
player receives anything. If player two accepts, the money is split
according to the proposal. Typically low offers, less than a third of
player one's endowment, are rejected as stingy, ensuring that both
players get nothing.
To test reciprocity, the game is varied so
that both players begin with an equal endowment, £10 say, but this time
player one's gift is tripled, and player two is then given the choice of
sending some money back to player one (the exchanges are conducted via
computer to ensure anonymity). For example, player one offers £3. Player
two now has £19 (£10 plus three times £3) and if he were to repay
player one's generosity by, for instance, sending him £4 back, player
one would leave the game with £11 and both would be better off. In
neuroeconomic parlance, the gift from player one is a "trust signal"
that prompts player two to reciprocate in kind.
When Zak tested
the blood of players who had demonstrated trustworthy behaviour, he
found that their oxytocin levels had increased in proportion to the
monetary transfer. When he tweaked the experiment by making the transfer
amount dependent on the random draw of a ping-pong ball, he found that
those who were trusted had oxytocin levels 41% higher than the controls.
In other words, it was the signal of trust and not the receipt of money
that had prompted the surge of oxytocin.
While this was strong
evidence of a correlation, however, it was not proof. Zak re-ran the
experiment but this time got half the participants to inhale oxytocin 50
minutes before playing (despite claims that oxytocin induces loving
feelings similar to ecstasy, in fact most people notice no change in
their affective state). Those who received the oxytocin spray sent back
17% more money compared with the placebo group. Not only that but the
number of people who showed maximal trust – sending their entire
endowment to a stranger – increased from 21% in the placebo group to 45%
in the oxytocin group.
He has achieved these results in repeated
tests, including variations of the game to check for cognitive
impairment (in one, players are asked to donate earnings to the Red
Cross or the Red Crescent Society: oxytocin prompts 48% higher donations
but only to the Red Cross, a charity with which north American
participants are more familiar and comfortable).
Zak's conclusions
are unequivocal. "Trust is chemical," he writes in one paper. "Social
norms, one's development history, and even current events affect trust,
but these do so by modulating OT release." Or, as he put it to me via
his Love phone: "HOME is a positive feedback loop. It literally feels
good to do good."
But Zak's proselytism does not end there. In recent papers and a forthcoming book,
The Moral Molecule: Vampire Economics and the New Science of Good and Evil,
Zak argues that oxytocin holds the key to human morality, policing the
"self-other divide" and subtly prodding us towards virtuous behaviour.
For
Zak, oxytocin solves the puzzle of why, in practice, people tend to be
more trustworthy than the classic economic model predicts. But if we are
wired for trust rather than naked self-interest and the oxytocin system
is really so powerful, why isn't everyone virtuous all the time, and
why did people in the riots trash and burn their own neighbourhoods?
Zak
invokes another hormone: testosterone. At times of stress, he argues,
we are physiologically in "survival mode", prompting the release of
testosterone and its bioactive metabolite, DHT. These stress hormones
prevent oxytocin from binding to brain receptors, tipping the balance
towards distrust and away from pro-social behaviour. This process, he
says, explains "the petty evils normally virtuous people exhibit". In
some cases, this bad behaviour may also be exacerbated by genetic and
environmental factors.
In his blood-test experiments, for
instance, Zak found that 5% of participants did not release oxytocin
when trusted. These individuals, he says, "have some of the traits of
psychopaths". There is also evidence that the oxytocin receptors in
rats' forebrains tend to atrophy when maternal nurturing is
"insufficient". Furthermore, he found that women who had been abused in
childhood tended not to release oxytocin when prompted by trust signals
in the games.
In the case of the riots, Zak believes that most of
the looters were probably "neurologically intact". The most likely
explanation for the mass criminality was that the line as to what was
morally acceptable within social groups in the affected areas shifted,
prompting the rioters to identify with "bad" influences. In other words,
it was a perfect storm of testosterone and "the wrong kind" of
oxytocin.
It is at this point that, according to author Raymond
Tallis, the alarm bells should be ringing. "My sense of the riots is
that the breakdown in trust didn't result from a sudden, catastrophic
oxytocin shortage but relates to such things as education and parental
attitudes. In other words, there's nothing that neuroeconomics can tell
us that isn't better explained at a sociological level."
Zak
argues that by measuring changes in the blood rather than relying on
fuzzy images from brain scans, his research is immune to the criticisms
usually levelled at neuroscientists. But Tallis questions whether
gauging blood oxytocin levels is a substitute for measuring the presence
of the hormone in the brain. "I might be similarly disposed to trust my
fellow human beings when I've had a couple of pints of beer," he says.
"But it doesn't follow that my whole attitude to being more disposed to
others is due to my brain alcohol level. Indeed, another couple of pints
on another occasion might have a very different effect."
Tallis's
fundamental objection, however, is that the game scenarios employed by
Zak and other neuroeconomists do not come close to mimicking real-life
economic and social interactions. "I don't have anything against
oxytocin
per se, it's a very fine molecule. It makes breasts
secrete milk, it makes uteruses contract, it gives women orgasms. Does
it really need another job?"
This is not the first time
neuroscience has waxed lyrical about a brain chemical: similar claims
were made about dopamine and serotonin. Indeed, in one paper, Zak
appears to hedge his bets by showing that these are also involved in the
HOME circuit.
However, Zak's faith is unshaken by the sceptics'
objections. "Our experiments are as causal as you can get, and the
results have been replicated many times," he tells me. "I wish you were
nearby so I could put you on some to see how it feels."
It's a tempting offer.
No comments:
Post a Comment