With a wedding looming on the horizon in my own family, I read with amusement as well as interest New Scientist writer Linda Geddes’ recent account of how she turned her wedding last July into a remarkable little science experiment to, as she put it, “probe what happens in our bodies when we say the words ‘I do.’ ”
Specifically, she wanted to find out whether the event would have any effect on blood levels of certain hormones in key members of the wedding party. Of particular interest was oxytocin, the so-called cuddle chemical that’s believed to play a central role in promoting social bonds of trust, empathy and generosity.
“If oxytocin really is the empathy chemical,” Geddes writes, “those close to us might have a hormone surge as they witness our public pair-bonding.”
For the experiment, she recruited the help of neurologist and oxytocin researcher Paul Zak, head of the Center for Neuroeconomics Studies in Claremont, Calif. He “leapt at the opportunity to translate his lab studies into real life” and flew to England for the ceremony.
Geddes also, of course, enlisted the help of her husband and 11 close family members and friends, who good-naturedly volunteered to give blood samples immediately before and after the exchange of wedding vows.
Now, that’s what I call a one-of-a-kind wedding.
As Geddes reports, oxytocin is a fascinating neurotransmitter:
It has long been known to help trigger childbirth as well as the release of milk during breastfeeding. And in the 1980s it transpired that, in American prairie voles at least, the hormone promotes pair-bonding between mates. Zak and other research groups have since found oxytocin at work in a range of human social interactions, including strengthening the bond between mother and child and fostering closeness after sex.
Zak has also recently reported that oxytocin levels tend to rise in people while they’re watching sad video clips. Those who expressed the most intense emotional responses to the clips displayed the highest spikes in the hormone.
Other research has suggested that oxytocin may incite the darker emotions of envy and Schadenfreude (gloating). And animal studies have shown that the hormone is related to higher levels of aggression. It may be, researchers now speculate, that oxytocin makes people more sensitive to all social cues, good or bad.
How did Geddes’ experiment turn out? The results, she says, came back from Zak’s lab a month after the wedding:
To my delight — OK, relief — in terms of oxytocin, our hypothesis proved correct. Both Nic [her husband] and I experienced a rise in the hormone during the ceremony as did the mother of the bride, the father of the groom and Nic’s brother — all the relatives tested.
The results from our friends were mixed: two did and five didn’t. … One bridesmaid was excluded from the analysis because her readings were so high they were off the scale. This could have been the result of a faulty test, or perhaps she naturally has very high levels.
(I think she’s kind to not name names. Also, Geddes doesn’t seem to consider that oxytocin’s association with negative emotions — such as envy — may have also contributed to the results of her experiment. But, frankly, who blames her for suppressing that thought?)
Except for the questionable bridesmaid, Geddes and her mother exhibited the biggest spike in oxytocin. According to Zak, “For every scenario we’ve looked at, women get the biggest rise. We know women are more empathic.”
Also interesting was the finding that family members, not friends, saw their oxytocin rise the highest — perhaps, suggests Zak, because family members have more genetically invested in the wedding.
Indeed, along a similar theme, Canadian researchers reported last week that homosexual men are much more likely than straight men (or women) to act altruistically toward their nieces and nephews. This avuncular, or uncle-like behavior, proposed the researchers, may be due to a biological imperative: an unconscious desire to ensure that their kin reproduce and thus pass down their own genes to another generation.
Not all the results from Geddes’ experiment came back as predicted, however. For example, her husband’s levels of vasopressin, the “mate-guarding hormone,” unexpectedly fell during the wedding ceremony. “Perhaps Nic didn’t need to aggressively defend you as you have publicly committed to him,” Zak told Geddes.
The real reason for weddings?
Although acknowledging that the sample size from this wedding experiment was too small to be scientifically significant, Zak believes the findings suggest that “public weddings evolved as a way of binding couples to their friends and family, perhaps to help out with future child-rearing,” says Geddes. “This may explain why weddings are more common than eloping. It might also be why some people cry at weddings.”
“Maybe,” said Zak, “the reason we have these wedding is not just because of the emotional contagion — the empathy, the love — but because these emotions are linked to helping maintain the human race.”