Darwin's Touch: Survival of the Kindest
Survival of the Kindest: Happy Birthday, Darwin.
Posted February 11, 2009
Two hundred years ago on February 12, Adam Gopnik writes in Angels and Ages: A Short Book About Darwin, Lincoln, and Modern Life, two pebbles -- Charles Darwin and Abraham Lincoln -- were dropped into the sea of life. Their ideas and forms of eloquence have redirected the currents of humanity.
One current of Darwin's thought is well-known. His theory of evolution by natural selection would require new genesis stories about the origins of life forms, less arrogant notions about man's place in the great chain of being, and a rethinking of our species as one in flux—and with rather hairy relatives.
Less well-known is a second current of Darwin's thought -- his conception of human nature. Think of Darwin and "survival of the fittest" leaps to mind, as do images of competitive individuals -- collections of selfish genes -- going at one another bloody in tooth and claw. "Survival of the fittest" was not Darwin's phrase, but Herbert Spencer's and that of Social Darwinists who used Darwin to justify their wished-for superiority of different classes and races. "Survival of the kindest" better captures Darwin's thinking about his own kind.
In Darwin's first book about humans, The Descent of Man, and Selection In Relation to Sex from 1871, Darwin argued for "the greater strength of the social or maternal instincts than that of any other instinct or motive." His reasoning was disarmingly intuitive: in our hominid predecessors, communities of more sympathetic individuals were more successful in raising healthier offspring to the age of viability and reproduction -- the sine qua non of evolution.
One year later, in The Expression of Emotion in Man and Animals, Darwin countered creationists' claims that God had designed humans with special facial muscles to express uniquely human moral sentiments like sympathy. Instead, drawing upon observations of his children, animals at the London zoo, and his faithful dogs, Darwin showed how our moral sentiments are expressed in mammalian patterns of behavior. In his analysis of suffering, for example, Darwin builds from pure empirical observation to a radical conclusion: the oblique eyebrows, compressed lips, tears, and groans of human suffering have their parallels in the whining of monkeys and elephants' tears. To be a mammal is to suffer. To be a mammal is to feel the strongest of Darwin's instincts -- sympathy.
The expression of sympathy, Darwin observed, was to be found in mammalian patterns of tactile contact. Inspired by this observation, Matthew Hertenstein and I conducted a recent study of emotion and touch that was as much a strange act of performance art as hardheaded science. Two participants, a toucher and touchee, sat on opposite sides of a barrier that we built in a laboratory room. They therefore could not see nor hear one another, and could only communicate via that five digit wonder, the hand, making contact on skin. The touchee bravely poked his or her arm through a curtain-covered opening in the barrier, and received 12 different touches to the forearm from the toucher, who in each instance was trying to communicate a different emotion. For each touch, the touchee guessed which emotion was being conveyed. With one second touches to the forearm, our participants could reliably communicate sympathy, love, and gratitude with rates of accuracy seven times as high as those produced by chance guessing.
Sympathetic touches are processed by receptors under the surface of the skin, and set in motion a cascade of beneficial physiological responses. In one recent study, female participants waiting anxiously for an electric shock showed activation in threat-related regions of the brain, a response quickly turned off when their hands were held by loved ones nearby. Friendly touch stimulates activation in the vagus nerve, a bundle of nerves in the chest that calms fight-or-flight cardiovascular response and triggers the release of oxytocin, which enables feelings of trust.
Research by Darlene Francis and Michael Meaney reveals that sympathetic environments -- those filled with warm touch -- create individuals better suited to survival and reproduction, as Darwin long ago surmised. Rat pups who receive high levels of tactile contact from their mothers -- in the form of licking, grooming, and close bodily contact -- later as mature rats show reduced levels of stress hormones in response to being restrained, explore novel environments with greater gusto, show fewer stress-related neurons in the brain, and have more robust immune systems.
Were he alive today, Darwin would likely have found modest delight in seeing two of his hypotheses confirmed: sympathy is indeed wired into our brains and bodies; and it spreads from one person to another through touch. Darwin, the great fact amasser that he was, would no doubt have compiled these new findings on sympathy and touch in one of his many notebooks (now a folder on a laptop). He may have titled that folder "Survival of the kindest."