The Age of Empathy (27 page)

In the same way that my office wouldn’t stay empty for long were I to move out, nature’s real estate changes hands all the time. Potential homes range from holes drilled by woodpeckers to abandoned burrows. A typical example of a “vacancy chain” is the housing market among hermit crabs. Each crab carries its house around—an empty gastropod shell—in order to cover its behind, literally. The problem is that the crab grows, whereas its house doesn’t. Hermit crabs are always on the lookout for new accommodations. The moment they upgrade to a roomier shell, other crabs line up for the vacated one.

It’s easy to see supply and demand at work in this hand-me-down economy, but since it plays itself out on a rather impersonal level it remains far removed from human transactions. It would be more interesting if hermit crabs were to strike deals along the lines of “You can have my house, if I can have that dead fish.” Hermit crabs are no deal-makers, though, and in fact have no qualms evicting owners by force.

Adam Smith thought that this approach characterized all animals: “Nobody ever saw a dog make a fair and deliberate exchange of one bone for another with another dog …” True, but Smith was
wrong to think that animals never trade, or that fairness is alien to them. He underestimated the sociality of animals since he believed that they didn’t need one another. My guess, though, is that the great Scottish philosopher would have been delighted to see how far the fledgling field of animal “behavioral economics” has come.

Let me illustrate this with an incident among capuchin monkeys that we taught to pull a tray with food. By making the tray too heavy for a single individual, we gave them a reason to join forces. On this occasion, the pulling was to be done by two females, Bias and Sammy. They successfully brought the food within reach, as they’d done so many times before. Sammy, however, collected her rewards so quickly that she released the tray before Bias had a chance to grab hers. The tray bounced back due to the counterweight and was now out of reach. While Sammy happily munched on her food, Bias threw a tantrum. She screamed her lungs out for half a minute until Sammy approached her pull-bar for the second time, glancing at Bias. She then helped Bias bring in the tray again. This time Sammy didn’t pull for her own good, because she only had an empty cup in front of her.

Sammy made this rectification in direct response to Bias’s protest against the loss of her reward. Such behavior comes close to human economic transactions: cooperation, communication, and the fulfillment of an expectation, perhaps even an obligation. Sammy seemed sensitive to the quid pro quo: Bias had helped her, so how could she refuse to help Bias? This kind of sensitivity is not surprising given that the group life of these monkeys has the same mixture of cooperation and competition of our own societies.

It is noteworthy that Sammy and Bias are unrelated. The tendency of animals to help kin is obvious in beehives and anthills, but also in mammals and birds. “Blood is thicker than water,” we say, and there is plenty of familial support in our own societies as well. Helping kin has genetic advantages, which is why biologists treat it quite separately from helping unrelated individuals. Here the advantages are far less obvious. So, why do animals engage in it? Petr Kropotkin, the Russian prince, offered an explanation at the beginning of the twentieth
century in his book
Mutual Aid.
If helping is communal, he argued, all parties stand to gain.

Kropotkin forgot to add that such a system won’t work unless everyone contributes more or less equally. Some parties, however, will be tempted to enjoy the fruits of the tree without watering it: In other words, cooperation is vulnerable to freeloaders. A few years after publication of
Mutual Aid,
Kropotkin corrected himself and did mention “loafers,” suggesting a solution:

Similarly, animals are selective about whom they work with, sometimes developing a “buddy system” of mutually positive partnerships. It’s not my intention to be gruesome about it, but a prime example is the way vampire bats share blood night after night depending on each individual’s success extracting it from unsuspecting victims. The latter are often large mammals, such as cows or donkeys, but occasionally a sleeping human. Between two buddies, bat A may have been lucky one night and, upon return to the communal roost, regurgitated blood for B. The next night, bat B may have been lucky and did the same for A. Vampire bats can’t go one day without blood, so they spread the risk this way.

Chimps go beyond this, however. Males chase after monkeys, which is an extremely challenging mission in three-dimensional space. Since hunters are more successful as a team than alone, they fit
the stag-hunt pattern. I once witnessed this spectacle live, which was fascinating except for the “fieldworker’s shower” I got due to the fact that chimps defecate profusely when excited. We had learned about the hunt through hooting and screaming mixed with the panicky shrieks of the monkeys. I found myself under a tree in which many adult males had gathered around the carcass of their favorite prey, a red colobus monkey. I am not complaining about the smelly state I found myself in, because it was a real thrill to watch all of this and follow the division of meat. The males shared among themselves as well as with a couple of fertile females.

One hunter usually captures the prey, and not everyone necessarily gets a piece. A male’s chance of getting a share appears to depend on his role in the hunt, which hints at reciprocity. Even the most dominant male, if he failed to partake in the hunt, may beg in vain.

Reciprocity can be explored in captivity by handing one chimp a large amount of food, such as a watermelon or leafy branch, and then observing what follows. As if to illustrate Reaganomics, the owner will be center stage, with a cluster of others around him or her, soon to be followed by spin-off clusters around those who obtained a sizable share, until all food has trickled down to everybody. Beggars may whimper and whine, but aggressive confrontations are rare. The few times that they do occur, it’s the possessor who tries to make someone leave the circle. She’ll whack them over their head with her branch or bark at them in a shrill voice until they leave her alone. Whatever their rank, possessors control the food flow. Once chimps enter reciprocity mode, their social hierarchy takes a backseat.

As in the 1980s hit song “What Have You Done for Me Lately?” the chimps seem to recall previous favors, such as grooming. We analyzed no less than seven thousand approaches to food owners to see which ones met with success. During the mornings before every feeding session, we had recorded spontaneous grooming. We then compared the flow of both “currencies”: food and grooming. If the top male, Socko, had groomed May, for example, his chances of getting a few branches from her in the afternoon were greatly improved. We
found this effect all over the colony: Apparently, one good turn deserves another. This kind of exchange must rest on memory of previous events combined with a psychological mechanism that we call “gratitude,” that is, warm feelings toward someone whose act of kindness we recall. Interestingly, the tendency to return favors was not equal for all relationships. Between good friends, who spend a lot of time together, a single grooming session carried little weight. They both groom and share a lot, probably without keeping careful track. Only in the more distant relationships did small favors stand out and were specifically rewarded. Since Socko and May were not particularly close, Socko’s grooming was duly noticed.

The same distinction is found in human society. When, at a conference on reciprocity, a senior scientist revealed that he kept track on a computer spreadsheet of what he had done for his wife and what she had done for him, we were dumbfounded. This couldn’t be right. The fact that this was his third wife, and that he’s now married to his fifth, suggests that keeping careful score is perhaps not for close relationships. Spouses do obviously maintain a measure of reciprocity, but mutual benefits are supposed to work themselves out over the long haul, not in a tit-for-tat fashion. In close and intimate relationships we prefer to operate on the basis of attachment and trust, reserving our marvelous accounting abilities for relationships with colleagues, neighbors, friends of friends, and so on.

We realize the tit for tat of distant relationships most acutely when it is being violated. Here’s a true story of something that happened to my brother-in-law. J. lives in a small seaside town in France, where he is known as the handyman he is. He can build an entire house with his own hands, as he is skilled in carpentry, plumbing, masonry, roof work, and so on. He demonstrates this every day at his own home, and so people naturally ask him for help. Being extremely nice, J. usually dispenses advice or lends a helping hand. One neighbor, whom he barely knew, kept asking about how to put a skylight in his roof. J. lent him his ladder for the job, but since the man kept returning, he promised to come take a look one day.

J. spent from morning until late evening with the neighbor, basically doing the job on his own (as the neighbor could barely hold a hammer, he said), during which time the neighbor’s wife came, cooked, and ate lunch (the main meal in France) with her husband without offering J. anything. By the end of the day, he had successfully put the skylight in, having provided expert labor that normally would have cost more than six hundred euros. J. asked for nothing, but when the same neighbor a few days later talked about a scuba diving course, and how it would be fun to do together, he felt this opened a perfect occasion for a return gift, since the course cost about 150 euros. So J. said he’d love to go, but unfortunately didn’t have the money in his budget. By now you can guess: The man went alone.

Stories like this make us uncomfortable, perhaps even angry. We closely watch reciprocity, and rightly so, given that it’s a core principle of society. Most of it takes place in an unspoken manner, because calling attention to past favors is seen as rude. Although the academic literature on this topic touts the human tendency to punish “cheaters”—who, like this neighbor, take more than they give—in real life punishment is rare. What could J. have done? Thrown a stone through the skylight? Punishment does occur when strangers play games in a psychology lab, but in a small town where everybody knows everybody and stays for years, sometimes generations, one has to choose one’s spiteful acts carefully. The only typically human option open to J. is that he could start gossip about what had happened.

But an even simpler solution is to avoid those who are short on gratitude. If one can choose between multiple partners, why not just go with the good ones, who can be trusted to respect past exchanges, rather than those lousy freeloaders whom we can all do without? We are like the clientele of a market where we pick and choose our partnerships, squeezing and smelling them the way the French do with cantaloupes. We want the best ones. People like J.’s neighbor will be out of luck.

This relates to the idea of a “marketplace of services,” which I proposed for chimpanzees long ago. The principle of supply and demand
reigns everywhere, from bees and flowers (the ratio between flowers and bees determines how attractive the former need to be to get pollinated by the latter) to the curious case of baboons and their babies. Female baboons are irresistibly attracted to infants, and not only their own, but also those of others. They give friendly grunts and like to touch them. Mothers are protective, though, and reluctant to let anyone handle their precious newborns. Interested females groom the mother while peeking over her shoulder or underneath her arm at the baby. After a relaxing session, a mother may permit the other a closer look. The other thus “buys” infant time. Market theory predicts that the value of babies goes up if there are fewer around. In a study of wild chacma baboons in South Africa, Peter Henzi and Louise Barrett found indeed that the length of time mothers were groomed was inversely related to the baby supply in the troop: Mothers of rare infants extracted a considerably higher price than mothers in a troop that had just enjoyed a baby boom.

The way primates trade commodities mimics our economies in surprising ways. We even managed to set up a miniature “labor market” among capuchin monkeys, which was inspired by their natural hunting behavior. These monkeys can be true cooperators, such as when they encircle giant squirrels, which are as hard to catch as monkeys are for chimpanzees. Afterward, the capuchins share the meat.

This situation can be modeled by requiring parties to collaborate but rewarding only one of them. In a variation on the cooperative pulling described for Sammy and Bias, we set up tests in which only one puller received a cup filled with apple slices. We called him the “CEO.” His partner had an empty cup in front of him, so pulled for the CEO’s benefit. We called this individual the “laborer.” Both monkeys sat side by side, separated by mesh, and could see both cups. From previous tests we knew that food possessors often bring food to the mesh, where they permit their neighbor to reach for it. On rare occasions they’d push pieces to the other.

As it turned out, if both monkeys brought in the food, the CEO shared more through the mesh with the other than if he had secured
the food by himself. In other words, he shared more after having been helped. We also found that sharing fosters cooperation, because if the CEO was stingy with his food, the success rate of the pair dropped dramatically. Without sufficient rewards, laborers simply went on strike. In short, monkeys seem to connect effort with compensation. Perhaps owing to their collective pursuits in the wild, they grasp the first rule of the stag hunt, which is that joint effort requires joint rewards.