When a mine shaft collapses on Bogart, he suffers a blow to his head. Like Muybridge, his mind shifts to the orientation of dog-eat-dog survival, and he leads the group into a nightmarish battle of distrust and exploitation. Ambiguous actions out in the desert—a partner claims to be searching under a rock for a Gila monster—appear to cynical eyes to be attempts at searching for the other’s hidden bags of gold. The language of friendship—“buddy,” “friend,” nicknames—shifts to the sharp, impersonal tones of last names. Suspicions about the imagined interests of others escalate into gun-pointing confrontations.
This high mountain drama parallels a central dynamic in the evolution of cooperation. How might cooperation, kindness and jen emerge in social groups composed of individuals who are better off pursuing self-interest? As we learned from the lessons of the tit-for-tat, an answer is found in the contagious goodness hypothesis. Simply put, cooperation and kindness will take hold in groups when jen becomes viral, when individuals can readily signal their kind intentions to others and evoke similar inclinations. In this fashion, people are less likely to experience the costs of being generous to competitive individuals, and more likely to enjoy the fruits of mutual cooperation—reciprocal trades of resources, sharing in parental care, and so on.
Jen becomes viral through behaviors that spread goodness from one individual to the next, thus setting in motion reinforcing, reciprocal cooperation. These behaviors would need to be powerful and fast, to counteract the mind’s automatic tendency to perceive threat, danger, and competition in nearby, fast-moving bundles of self-interest—namely other humans. These behaviors would need to operate on the bodies of others, to shift the nervous system away from its potent, trigger-happy fight/flight tendencies toward a physiological profile more conducive to cooperation and kindness. These contagious behaviors would need to be easy to use and readily adaptable to the close proximity of the daily interactions of our hominid predecessors. These contagious behaviors, as signals of cooperation and trust, would need to be easy to perceive and hard to feign.
The scientific study of touch reveals the tactile modality to be an ideal medium in which individuals spread goodness to others. We can readily put touch to use in the close encounters of group living—when negotiating close spaces, working together, flirting amid rivals, playing around, or allocating scarce resources. Touch triggers biochemical reactions in the recipient—activation of the orbitofrontal cortex and deactivation of the amygdala, reduced stress-related cardiovascular response, and increased neurochemicals like oxytocin—all of which promote trust and goodwill between individuals. Touch, my studies show, is the primary language of compassion, love, and gratitude—emotions at the heart of trust and cooperation. To understand why touch can make jen viral, we must first look to evolution of the largest organ of the body—the epidermis—and that five-digit wonder, our hand.
SKIN AND HAND
In humans, shifts in the morphology of our organs of communication have emerged with developments in our ultrasociality. So it is with touch: Evolutionary shifts in our skin and hands have led to a central role of touch in our ultrasocial relationships. A first big shift was the loss of most of our body hair—we became, in Desmond Morris’s famous phrasing, naked apes. Why? You may be tempted by the aquatic ape hypothesis—that for a period of our evolution we actually lived largely in the water, thus losing our hair, as other water-bound mammals such as dolphins and whales did. As readily as this hypothesis appeals to our love of lolling about in the water on hot summer days and our sense of communion with whales and dolphins, it makes little evolutionary sense. As Nina Jablonski has argued in her book Skin, water holes on the African savannah were highly dangerous places, brimming with quick-striking predators, all the more so to a species not terribly adroit in the water, as in the case of our hominid predecessors. Had we been aquatic apes, we wouldn’t have done very well in the game of survival.
The actual explanation for our hair loss is less flamboyant but eminently more sensible—we lost our hair in hominid evolution for purposes of thermoregulation. A thick carpet of body hair would have been dangerously hot on the savannah—the locale of our early evolution. In this hot, arid environment, we increasingly relied on the rich network of sweat glands distributed throughout the skin to keep ourselves cool. These glands function more effectively in the absence of hair.
One by-product of this shift toward hairlessness is that our skin evolved into a most remarkable interface between our inner and outer worlds. Human skin is the largest of our organs, weighing six pounds and covering eighteen square feet. Its distinct layers house a veritable industrial zone of biological factories accomplishing several functions essential to human survival. A rich network of blood vessels, sweat glands, and hair follicles and surrounding muscles lie under the skin. There are cells producing proteins called keratins, which account for the strength and resilience of the skin. Cells known as immigrant cells move into the skin during development from other parts of the body and accomplish three tasks. Melanocytes produce the skin’s pigment, melanin, which protects our bodies from the dangers of ultraviolet rays. Langerhans cells are part of our immune system, and represent our body’s first response to viruses and bacteria. Finally, Merkel cells reside at the ends of sensory nerves in the skin and respond to touch. Some of these cells, in particular in the arm, face, and leg, appear to respond to slow, light touch, and may be involved in the release of opioids trigged by contact from others. The skin is our protection against harmful physical agents—sharp branches, ultraviolet rays, bacteria and viruses—in the external world. As important as the skin is to keeping the bad stuff out, it is vital to bringing the good stuff in.
Just as critically, evolutionary changes in the morphology of the human hand likewise facilitated the development of the tactile language of emotion. As humans began to walk upright, the hand changed dramatically. We acquired the opposable thumb—the morphological darling of many evolutionists. We also developed more dexterous fingers. Chimp thumbs are much shorter, in relation to the rest of their hand, than the human thumb. Humans, unlike chimps or bonobos, became able to make precision grips between thumb and forefinger, and power grips using the entire hand. These shifts in the morphology of the hand, most obviously, allowed our hominid predecessors to emerge as the first complex toolmakers in primate evolution, fashioning sophisticated arrowheads, clothes, baskets, and so forth. In the process, we developed profoundly expressive hands. Our hands allowed us to point with precision, a critical part of the child’s emergent understanding of the referential quality of language: Words refer to things. With the refined acrobatics of our hands and fingers, we learned to signal different objects and states with what are known as emblems—gestures that translate to words. With our hands we learned to convey internal states with specific patterns of touch.