The American academic Paul Zak is renowned among his colleagues for two things that he does to people disconcertingly soon after meeting them. The first is hugging: seeing me approach across the library of his club, in midtown Manhattan, New York, he springs to his feet, ignoring my outstretched hand, and enfolds me in his arms. The second is sticking needles in their arms to draw blood.
In the event, I escape our encounter unpunctured, but plenty of people don’t: Zak’s work, which he refers to as “vampire studies,” has involved extracting blood from a bride and groom on their wedding day; from people who have just had massages, or been dancing; from Quakers, before and after their silent worship; and from tribal warriors in Papua New Guinea as they prepare to perform traditional rituals.
That all these people submit so willingly to his needle may have something to do with the fact that he is charm personified. A square-jawed, 50-year-old Californian with good hair, a sunny disposition and a media-friendly nickname (“Dr Love”), Zak gives every impression of having been constructed in a laboratory charged with creating the ideal deliverer of TED talks. “For further information, to request an interview, or even just a hug from Dr Love,” reads the press release that accompanies his new book, The Moral Molecule, “please contact...”
What drives Zak’s hunger for human blood is his interest in the hormone oxytocin, about which he has become one of the world’s most prominent experts. Long known as a female reproductive hormone — it plays a central role in childbirth and breastfeeding — oxytocin emerges from Zak’s research as something much more all-embracing: the “moral molecule” behind all human virtue, trust, affection and love, “a social glue,” as he puts it, “that keeps society together.” The subtitle of his book, “the new science of what makes us good or evil”, gives a sense of the scale of his ambition, which involves nothing less than explaining whole swaths of philosophical and religious questions by reference to a single chemical in the bloodstream. Being treated decently, it turns out, causes people’s oxytocin levels to go up, which in turn prompts them to behave more decently, while experimental subjects given an artificial oxytocin boost — by means of an inhaler — behave more generously and trustingly. And it’s not solely because of its effects on humans that oxytocin is known as “the cuddle hormone:” for example, male meadow voles, normally roguishly promiscuous in their interactions with female meadow voles, become passionately monogamous when their oxytocin levels are raised in the lab.
Trust is in the blood
The aforementioned wedding — of the New Scientist reporter Linda Geddes and her fiance — took place at a country house in Devon, south-west England, where Zak set up a temporary research station. He took blood samples, before and after the wedding vows, from the bride and groom, close family members, and various friends in attendance, then flew back his spoils — 156 test tubes, packed in dry ice — to his laboratory at Claremont University, in southern California. There, he discovered the results he had been expecting: the ceremony caused oxytocin to spike in the guests. And it did so in spookily subtle ways: the bride recorded the highest increase, followed by close family members, then less closely involved friends, “in direct proportion to the likely intensity of emotional engagement in the event.” (Only the groom bucked the trend: testosterone interferes with oxytocin, and his testosterone was surging.) Mapping the wedding’s oxytocin levels gave rise, in Zak’s vivid phrase, to a human “solar system” with the bride as the sun, the hormone finely calibrated to the emotional warmth each guest felt. “It was amazing,” Zak recalls. “Just this perfect sense of how oxytocin attunes to the environment.”