THE HUMAN FASCINATION with justice is as old as civilization itself. Some of our most cherished and celebrated documents reflect this: the U.S. Constitution and the Universal Declaration of Human Rights are two of the more recent examples. Our tradition of codifying our rules of conduct goes back to the Magna Carta, the Old Testament, and Hammurabi’s code. Human society is obsessed with laws and justice. Even when we gather to play games, we first establish the rules. We cannot even have fun without also imposing rules.
But what is justice? Is it nothing more than a man-made set of rules that we have chosen to impose on our neighbors and ourselves in order to promote social order? Does justice stem only from civilization? Is a sense of justice a unique feature of very high-level cognitive ability? These questions focus solely on the human application of justice in a formal setting, but is there something deeper than that? Is there a biological basis for the concept of justice?
One thing about justice that is particularly striking is how similar it is in diverse cultures and histories around the world. Too often, we get caught up in the contrasts between cultures, but the similarities far outnumber and outweigh the differences. Of course, those similarities could come from social forces or just common sense about the need for stability, fairness, and harmony in society. However, they could also come from our biology. Could it be that we are programmed to recognize and desire justice?
INTOLERANCE OF INEQUITY
Researchers at Georgia State University led by Sarah Brosnan recently conducted a few simple but telling experiments involving chimpanzees.1 A group of chimps had been trained, individually, to retrieve and then surrender tokens in exchange for food treats. The price was set: one token bought one piece of food. Sometimes the food was a grape, and sometimes it was a carrot piece of similar size. Like most of us, the chimpanzees preferred the grape and would select it over the carrot if given the choice. However, if presented with only the carrot, it was a prize they would happily eat in exchange for the silly token that was of no use to them otherwise.
Everything went fine in this experiment until two chimpanzees were brought in together and allowed to earn their treats in full sight of each other. If the two chimpanzees repeatedly earned the same reward, be it carrots or grapes, they were happy to continue the task, each largely ignoring the other. However, when one chimpanzee earned a carrot after seeing another chimp earn a grape, more often than not, he did not accept it. Instead, he would refuse the carrot, grow restless, show obvious signs of agitation, and perhaps even throw a tantrum. Before, he just preferred the grape but was happy with a carrot. Seeing another chimp get a better reward for the same task was more than he could bear.
I doubt this scenario will sound at all unfamiliar to any parent with two children. The perceived value of a treat or reward can be strongly influenced by the treats or rewards that others receive. And this human feature is in no way limited to children—adults are just as susceptible to this kind of behavior. But the question is, should we be surprised that it is seen in animals such as chimpanzees?
For whatever reason, the image of a chimpanzee refusing a reward because it is not as good as the reward received by another just seems so human. I find this curious, too, because it is not exactly a mature or sensible way to react. It is kind of obnoxious, actually. (Therein is the resemblance, I suspect.)
Brosnan’s group provoked the chimpanzees further. In another round of experiments, researchers would first show the chimpanzees grapes, but when they returned with their tokens to purchase them, they were instead given carrot pieces. Again, the chimpanzees very often refused the carrot pieces, regardless of their previous willingness to earn the carrots by performing the same tasks. They recognized the unfairness of the situation and refused to play along.
Something about this experiment seems almost cruel, like when someone teases their dog by saying words like treat and walk but then does not follow through. But that is not what the experiment was—there was still a reward there for the taking. All the chimpanzees had to do was accept it. They refused to do so because the reward did not measure up to the expectation that they had been led to. They thought they had a deal, and then the terms were changed on them. In human terms, this is called the bait and switch, and it turns out that chimpanzees are no more amused by it than we are.
We might be inclined to chalk these two examples up to good old-fashioned greed—the chimpanzees wanted the grape, plain and simple, and knowing it was out there made the carrot look less attractive. However, the researchers also found something that I doubt they expected. Sometimes—not all the time, but sometimes—the chimpanzee that was given a grape (the better reward) would refuse it if he saw that his buddy got only a carrot. He would refuse the better reward because someone else had been cheated. Clearly, this refusal goes beyond greed. The chimpanzees could recognize the inequality going on, and they would not stand for it, even when they were the beneficiaries. Some of these chimpanzees preferred to go hungry and throw a tantrum rather than tolerate the unfair conditions.
If this is not the beginning of a system of justice, then I do not know what is. Equal pay for equal work is what we are talking about here. And it turns out that this principle is not just some constructed ideal or the product of an advanced and progressive society. It is part of the natural psychology of us and our closest relatives.
The chimpanzees were clearly experiencing a conflict. Their own self-interest should have told them to take the reward—any reward—rather than risk getting nothing by throwing a tantrum. Instead, they exercised a different value: fairness. Unlike humans, no one ever sat these monkeys down and taught them the Golden Rule or told them that God was watching them—they just knew it was wrong. Something resembling a sense of justice therefore must be hardwired into the chimpanzee brain.
Biologists refer to this behavioral trait as “intolerance of inequity.” If chimps and humans both understand fairness, this means that it likely evolved in some common ancestor of the two. The most recent common ancestor of both chimps and humans (and bonobos) lived around six or seven million years ago. The concept of fair pay was around a long time before the first humans walked the Earth.
The work with chimpanzees described here was not the first of its kind. In fact, Professor Brosnan, while studying under the mentorship of Frans de Waal, had previously performed a similar experiment with a species of New World monkeys called capuchin monkeys. Although the experiments with the capuchins did not probe as deeply as those with the chimps, the researchers found that the monkeys would happily turn in their tokens for cucumber pieces—unless they had previously seen another monkey receive a grape for performing the same task.2 (You can watch a YouTube video of a capuchin accepting a cucumber, then later rejecting it—even throwing it at the scientist—after seeing another monkey getting a grape. Search for “capuchin monkey fairness experiment.”)
That such similar behaviors are observed in two primate lineages that have been geographically and genetically separated for so long points to a common root cause that is at least as old as the evolutionary branching itself—and by root cause I mean genetics, of course. Since New World monkeys have been evolving separately from apes for at least forty million years, we can assume that primate species have understood fairness for at least that long.
Even more recent work with chimpanzees reveals the same sense of fairness but in a different scenario, the ultimatum game (UG). Variations of the UG are commonly used when studying the psychology of people, especially children, and in something called game theory. In its simplest form, the UG goes like this: Person X is given an amount of money but has to propose how to split it between himself and another person, Person Y. Once X has made an offer for the split, Y can choose to accept or reject it. If he rejects, neither party gets anything. Although there are several interesting things to probe about human nature with this experiment, most commonly we focus on Person Y. Once the offer is made, whatever the offer is, Person Y should accept it because to reject it means he gets nothing. In practice, however, most of the time, Person Y rejects the offer if it is less than around 20 percent of the total amount.
Even if the offer is only 10 percent of the total, that is better than nothing. Would the rational choice be to accept whatever offer is given? Well, as we all know, humans are not purely rational. We have other forces at work that influence our decision making, and one of those forces is the intolerance to inequity, as shown by the UG. The UG has been used to study intolerance to inequity in humans for many years, so why not try it with chimpanzees?
That is exactly what Professor Brosnan’s group did. They invented a new version of the UG to use with chimpanzees.3 In this setup, Chimp X was given two tokens to choose from, both of which would earn him some bananas. However, he had to give whichever token he chose to Chimp Y, and then Chimp Y had to submit it to the researchers so that the chimps could get their reward. The catch was that one of the tokens represented an even split—three bananas for each chimp. The other token earned five bananas for Chimp X and only one for Chimp Y. Remember that Chimp X could not turn the token in himself; he needed the help of Chimp Y.
Under this scenario, Chimp X very quickly decided to pursue the “fair” course of action. However, if Chimp X needed no help from Chimp Y and could do whatever he liked, sometimes known as the dictator game, he submitted the token that got him the larger reward, with no regard for the other chimp. In other words, if cooperation was needed, Chimp X knew that he had better pursue the fair option, rather than the unequal option.
Although Chimp X was motivated by self-interest in both scenarios, the difference in behavior is striking because it reveals that he recognized that the two scenarios were different. In other words, he appreciated the difference between equality and inequality. Furthermore, he recognized that if he needed the cooperation of Chimp Y, equality was the best choice. In this way, fairness is a value in chimpanzee social behavior, but only insofar as it aids cooperation. This phenomenon highlights what will become a recurring theme in this book: evolution and natural selection are not forces that favor only selfishness and brutal competition. Sometimes, one’s self-interest is actually served through cooperation and fair play, and many nonhuman animals recognize this.
The interesting question is this: What motivated Chimp X to share the bananas equally? What was he afraid would happen?
A doubter of these results might say that this was just a cold calculation on the part of Chimp X. He is betting that if he chooses the “fair” option, thus making a short-term sacrifice, it will lead to better rewards in the future because it will maintain the cooperation of Chimp Y and thus keep the banana train rolling. Maybe it is still selfishness, just a more sophisticated and calculating form of it. My response is that that is what fairness is. It may very well be that justice is simply a more comprehensive and more sophisticated form of self-interest.
We do not insist on rules to be sure that we do not cheat; we insist on rules so that others do not cheat. Our sense of fairness expresses itself much more strongly when we are the victims of unfairness than when we are the beneficiaries. I am not suggesting that there is no such thing as a selfless act, although many others have. What I am saying is that at least part of the motive of fairness comes from self-interest. The greatest of all rules in Christianity is called the Golden Rule: do unto others as you would have them do unto you. Even this rule, plainly stated, asks us to reflect on repercussions for ourselves. We are asked to consider how unfairness would affect us before we inflict it on others—the idea being that, if we all live by these rules, we will not be victimized.
What about species other than monkeys? It turns out that we primates do not stand alone with our intolerance of inequity. This behavior is present in our best friends as well. A 2008 study with dogs demonstrated this quite clearly. In that study, when dogs were asked to “shake” (aka “give paw”), if they knew they would get a treat, they would comply with the request every time. No surprise. But if there were no hint of any reward, they would only satisfy the request about twenty times out of thirty. However, if they saw other dogs getting a treat, while they did not, for completing the same assignment, they would complete the task just twelve times out of thirty. In addition, the researchers observed visible agitation, barking, and aggression among the dissatisfied pups.4 It sucks to not get a treat. It sucks even worse to not get a treat while others do.
Intolerance of inequity is being observed in a diverse and growing list of mammals, which would push its origins back even further to well more than one hundred million years ago.5 Why would this behavior have evolved in the first place? It is difficult to imagine that throwing a tantrum every time you perceive being slighted would lead to increased survival and reproductive success. It is also hard to imagine any good coming from it at all. What purpose does this intolerance of inequity serve for survival and success?
COOPERATION AND PROSOCIAL BEHAVIOR
Once again, we find ourselves faced with the notion that the rules of natural selection may not be able to explain a behavior. Would survival of the fittest reward the cheaters and punish the righteous? Actually, if we consider the long-term effects of demand-for-justice behavior, a distinct Darwinian advantage emerges: fairness is essential for cooperation, and individuals who cooperate fare better than those who do not, at least in certain contexts and in certain species.
In a later chapter, we will see how birds and mammals have evolved reproductive behaviors built around cooperation, instead of just competition. It turns out that animals, especially mammals, often cooperate in many other ways as well. I am focusing my discussion of fairness and cooperation on mammals because, while cooperation is not unique to mammals, our class of animals has definitely taken it to the highest level. Most mammals are social species living in communities from tens to hundreds of individuals. Even those mammal species that have returned to individualistic and solitary lifestyles at least begin their lives in the social context of nursing and weaning. (The word “mammal” comes from the Latin root mamma, which means breast.)
For a social species, cooperation is essential to living together peacefully. The community cannot thrive if individual members try to sneak more than their fair share or get away with not pulling their weight in the herd or pack. In order to enforce discipline and acceptable conduct, there must be a genetic drive to punish those who are out of line.6 If and when selfish or uncooperative individuals are ostracized, they will likely suffer elimination from the gene pool, as members of social species generally do not fare well on their own. Natural selection would thus select against the selfish through their banishment and subsequent failure to reproduce. However, before a social species can discipline unruly members, it first must be able to recognize injustice when it sees it. This is the intolerance to inequity that researchers have found.
Behaviors that focus at least as much on the good of others as of ourselves are called prosocial. Scientists have classified plain old cooperation separately from truly prosocial behaviors because cooperation can be purely selfish in nature. “If we help each other, I eat. If we do not, I will go hungry. Therefore, I will help you.” Prosocial behaviors, on the other hand, come with no direct benefit to the individual, only to others or to the group. These kinds of behaviors were once thought only to be found in humans.
However, chimpanzees have now also been found to exhibit prosocial behaviors. In a recent study, chimpanzees were asked to choose between two tokens. One token got them a small reward, nothing more. The other token earned them the same reward but also allowed a second chimp (unrelated and unfamiliar) to get the reward. The two chimps were separated but could see and hear each other and, importantly, never switched places, so there was no immediate chance of reciprocity. What the researchers found was that the chimpanzees were happy to help out a stranger by selecting the token that led to a reward for both chimps.7 “Why not? No skin off my back!” This is prosocial behavior. No one is lining up to give them a Nobel prize, but choosing to benefit others with no gain for yourself is the definition of prosocial behavior. It is not, however, altruism. Altruism requires a cost for the generosity, and there was no cost in this situation.
Interestingly, the researchers found that the behavior of the second chimp—the one that benefited from the prosocial generosity—affected the likelihood that the first chimp would choose to help her. (All the chimps were female in this experiment, for simplicity.) If the second chimp called attention to herself by tapping or vocalizing in a gentle, nonthreatening way, the first chimp was even more likely to help. This could be considered asking or begging. However, if the chimp was loud or aggressive, jumped around, or was obnoxious in any way, the first chimp was substantially less likely to help. Ask, and ye shall receive. Demand, and you can go $#@ yourself.
This, too, seems familiar. Imagine the following scenario: you are walking down the street, and someone just in front of you drops a couple dozen pencils on the sidewalk. Maybe you would not stop, but you probably would. This does not cost you anything, so it is prosocial to stop and help. However, what if you were late and in a hurry? In that case, there would be a cost to you, so this would be altruism. Under these conditions, you would be less likely to stop. After all, there are other people who can help, right?
Further still, if the person who dropped the pencils looked at you pleadingly and desperately, you would probably stop, regardless of whether or not you were late. On the other hand, if this person yelled at you and demanded that you stop and help, you would probably walk on by, even if you had all the time in the world, right? This is such a simple scenario, but it reveals a rather deep connection in the prosocial behavioral impulses between humans and chimpanzees.
The story does not end with a sense of equality of resources. Other manifestations of fairness are seen in nature as well. Professor Marc Bekoff has published many articles detailing the rules of fairness that govern wolves, particularly when they play. One striking phenomenon is the self-imposition of a “handicap” when a larger and stronger wolf plays with a smaller one. The larger wolf will approach the smaller one in a submissive posture, which gives the former a distinct disadvantage in the ensuing wrestling match.8
Why would the larger wolf handicap herself? Well, if you are a big, strong wolf, sometimes the only way to find a playmate is to agree to level the playing field. This, too, hints at a sense of fairness. Both wolves, big and small, recognize the advantage that the larger wolf has. If you were a small wolf, why would you want to start a wrestling match when you know you were going to get your clock cleaned? Nevertheless, as we saw in chapter 1, the instinct to play is hardwired. Both wolves really want to play, but they also recognize the inequality of the pairing. This poses a conundrum. The self-imposition of a handicap is the solution to the conundrum. The larger wolf puts herself at a disadvantage so that the smaller wolf will play along. In fact, the stronger wolf will also allow the smaller wolf to bite her, which she could easily prevent, provided the play bites are not too hard.9
Perhaps even more telling is that when young wolves play, if one wolf goes too far and bites hard enough to cause injury, the game is stopped and the offense must be apologized for. Wolves have a way of offering apologies. The offending wolf will approach in a submissive posture, hanging her head low in what is called an apology bow. If an apology is not made after the offense, no wolves will play with the offender again. Given how important these play fights are for the social cohesion and dominance hierarchy of the pack, this is a dire consequence. A wolf with whom no one will play subsequently loses any hope of a dominant position in the pack.10
The same system of handicapping during play-wrestling is also seen in coyotes, close relatives of wolves. However, with coyotes, the punishments are even more severe. A single offense of biting too hard can get an individual permanently shunned from the pack.11 Although coyotes are often solitary as adults, when youngsters are ostracized too early, they suffer a much higher mortality rate, making this punishment quite harsh. You break the rules; you pay the price. Justice, it seems, is not just about fair play. There must also be punishments meted out to the offenders, and forms of social punishment have been documented in a variety of species.12
This submissive-apology behavior is also seen in domesticated dogs, the direct descendants of wolves.13 We see the “I’m sorry” posture any time a dog gets into the trash, has an accident in the house, or, in perhaps the most resonant example, gets too rough with the kids. Importantly, while it could be argued (unsuccessfully, it turns out) that apologizing is a learned behavior in wolves, no such argument could reasonably be made for domesticated dogs. No one sits their dachshund down to teach him how to submissively apologize for an offense. He just knows. There is some sort of “guilty gene” at work, again demonstrating the genetic basis of complex behaviors.
Once again, I am reminded of my family sheepdog, Daisy. We had a large room in the house where Daisy was not allowed to go. The dog-free formal family room was for when we had visitors who did not particularly enjoy a big dog jumping into their laps (like Grandma and Grandpa). Daisy never hid her resentment of this rule and would frequently stand or lay down just on the threshold of the room, as if to test the rules and inch her way across the boundary. If she was ever suffering from a stomach issue or we inadvertently left her too long without a bathroom break and she could not hold her bowels any longer, without fail, she would relieve herself in that room—the dog-free room. Every single accident she ever had inside the house took place—with no one looking—in the one room that she was not allowed to enter.
Did she choose to go in that room in order to get back at us? Was this some sort of revenge for imposing the rule that she hated so much? Or was this her attempt to cover her tracks and fool us into thinking that it was someone else? “Guys! Surely it wasn’t me that did it—I’m not even allowed in there, remember?”
Whatever her reasons, there was no hiding her actions. The guilty look gave her away every time. Upon our return, as soon as we opened the door, if she did not run to greet us, we knew something was up. Inevitably, we would find her sitting in some corner of the house, giving her most convincing apology bow. The guilt program deep inside her wolf brain had been activated, and she was desperate to receive the punishment necessary to satisfy that guilt, allow forgiveness, and restore harmony in the social unit. She was just like a wolf, and we were her pack.
Clearly, handicaps and apologies seem to be ingrained features of the social lives of canids, the group that includes wolves, coyotes, domestic dogs, dingoes, and jackals. Investigators have also observed self-handicapping in five different monkey species.14 Interestingly, scientists studying chimpanzee play have found that the tendency to self-handicap appears spontaneously and early in childhood.15 Chimpanzees do not learn this behavior, either by instruction-demonstration or through negative consequences following infractions. Although it could be fairly said that positive consequences reward the self-handicappers when they are able to better attract playmates, the point remains that the behavioral instinct to do this is inborn.
Self-handicapping thus seems to be a common, even near-universal feature of physical-competitive forms of play in mammals, including our closest primate relatives. Is this something that we humans do as well? I think it is pretty obvious that we do. When amateur golfers regularly play together, they compete against each other utilizing their respective “handicaps” to level the playing field. Their individual skill levels are normalized and written away in order to establish a new common baseline. This makes the competition fair. Golfers with very different skill levels can play together and compete because they begin from different places based on their handicap level.
In fact, the word “handicap” was originally developed for exactly this purpose, rather than to mean a physical limitation as it came to be used later. There was a bidding and trading game in medieval England called hand in cap that involved an umpire establishing monetary valuation of possessions being bid on by two competitors. Somehow, the practice of a third party establishing baseline weighting between two unequal competitors became known as handicapping, and it was applied to horse races as early as the eighteenth century. Horses with stellar racing records were “handicapped” by having weights added to their saddles. And voilà—the word “handicap” emerged as something used to weaken an otherwise stronger individual.
For some reason, this term has fallen out of favor when referring to individuals with a physical or mental impairment. I suppose it could be because of a false impression that the word handicap means “not as capable.” There is also the apocryphal story that the word handicap began as a pejorative for beggars who had their “caps in hand,” an urban legend that appears to have been invented out of whole cloth. I feel that if more people understood that the word handicap originated as something applied to overachievers to make things more competitive for the rest of us, maybe it would not have been replaced with words like disabled. I cannot for the life of me see how the word disabled came to be preferred over handicapped, but I digress.
My point here is that the concept of handicapping is very common in human culture, especially gaming. In high school sports, there are different “classes” in which the teams compete so as to ensure that a tiny rural high school is not routinely obliterated by a huge urban powerhouse. In professional sports, the draft, where new players are selected, is heavily tilted to favor the lowest-performing teams from the previous season; boxing is organized by weight class; and so on. The point is that we prefer a fair fight to a lopsided one.
Further, the handicapping of stronger entities is not limited to sports and play. Our system of taxation employs this as well. Every single industrialized nation employs a progressive tax code in which the more income you have, the greater the marginal tax rate you are subject to. (At least, that is how it is intended to work.) Similarly, economically disadvantaged individuals and families are given government support for food, housing, and medical care; a baseline of education is provided to all children at no cost; and so on.
Our justice system also incorporates features of handicapping. For example, in the United States and most other Western countries, there are laws against price fixing that are designed to ensure a fair contest among competitors and prevent coalitions and scheming. There are also related laws against monopolizing a certain industry. If one company controls all or nearly all of a certain market, even if there is no illegal activity, it can be forced to dissolve into separate companies by federal regulators, as happened with AT&T in the early 1980s. While it is true that some of these antitrust laws are designed to protect consumers, there is another reason that they remain incredibly popular despite economic studies that show that industrial monopolies are always short-lived: monopolies just seem unfair.
To be sure, I do not presume to boil all of these complex social-political-legal issues down to a simple biologically ingrained instinct toward handicapping and intolerance to inequity. However, I do maintain that the fairness instinct is at least partially responsible for how we construct our social structures. I do not see it as controversial that our values are heavily influenced by our biology. Like other mammals, we are programmed to recognize inequality and be upset by it. We are programmed to seek fair play through handicapping. It seems rather obvious to me that these features of our biology would become features of our societies.
RECIPROCITY
Another manifestation of fairness and justice, as we understand them, is the concept of reciprocity. You do this for me; I will do that for you. I will give you this if you pay me with that, and so on. This forms the basis of our whole economic system—the exchange of goods and services for other goods or services of equal value, with currency and credit as handy measuring sticks for the value of those goods and services. Failure to honor this system of reciprocity is considered a crime that we call fraud or theft. Did the concept of reciprocity originate in humans, or does it predate us?
Reciprocity has been observed in a wide variety of species, including vampire bats, one of the most feared and reviled creatures in nature. These little guys go on nightly hunts to search for a nice, unsuspecting pig, cow, or horse that is fast asleep. They generally obtain their nourishment from one nightly meal, eating as much as they can without compromising their ability to fly. If they are unsuccessful on any given night, they can usually survive until the next night. However, like most flying animals, bats do not have voluminous fat deposits, and their metabolism burns fast. Two nights without eating is often fatal.
Researchers studying the feeding behaviors of vampire bats in Costa Rica observed that, at the end of the night, a bat that was not successful in finding food would often confront one that had been successful and “beg” for the other to share.16 Surprisingly, the successful bat would often agree and feed his unlucky friend by regurgitating some of his last meal into the other’s mouth. It is a disgusting scene, to be sure: one of the ugliest creatures in the world vomiting blood into the mouth of another. At the same time, it is rather beautiful: a gentle soul selflessly giving some of his food in order to save his friend from starving.
Remember that bats, like most animals in the wild, are in a constant struggle for survival, and the threat of starvation is very real. To give up as much as 20 to 30 percent of your meal means that you will be at greater risk of starving if you do not find food the next night. This is the essence of altruism: helping another at significant cost to yourself.
It turns out, however, that the altruism is not as pure and selfless as it appears to be at first blush. The bats that share food expect to be shared with the next time they come up empty after a night of hunting. You scratch my back, and I scratch yours. As it turns out, these bats remember which of their friends has previously shared with them and are much more likely to return the favor when the tables are turned. Similarly, if a well-fed bat snubs another that is hungry and begging, the rejected bat will return the snubbing if the “frenemy” comes begging in the future. This is not pure altruism; it is reciprocal altruism.
Cooperation and reciprocity have been documented in chimpanzees for decades. Scientists in the 1930s trained chimpanzees to pull a truck of food to their cages using ropes.17 When the truck was too heavy for one chimpanzee to pull, two chimpanzees would work cooperatively to pull the truck. There are videos of this on YouTube that show the impressive task-oriented coordination that chimpanzees are capable of. But that is not the surprising part. When one chimpanzee was already well fed, he could still be coaxed into helping pull the truck by a hungry cagemate.18 Although he certainly did not show as much determination in the task and was easily distracted, it was rather generous of him to help at all. As soon as the truck was pulled close enough, the hungry chimp took all of the food for himself without so much as a thank-you. Why did the well-fed chimp help? Probably because he knew that the tables could easily be turned in the future. It is generally a good idea to help when you can—you never know when you may need a favor yourself. Most humans understand this concept all too well.
There is no shortage of examples of reciprocal altruism in nature. Some species of birds have a specific warning call that they use to tell others that a predator is nearby.19 By calling loudly, these whistleblowers put themselves in great danger by attracting the attention of the predator, but they do so nevertheless, even when they are looking out for others who are not even in their own family. They perform the act because they expect to benefit when someone else is on the lookout.
In chapter 4 we will discuss the existence of prostitution in animals, which could be seen as a form of reciprocity—trading sex for food or other goods. There are other kinds of “service swaps” as well. For example, Vervet monkeys will groom each other for parasitic bugs, and “returning the favor” is expected and enforced.20 The same is true for many species of birds that will help preen each other, even if they are not related.21
In fact, the reciprocity of “grooming” is so common in nature that there are many examples of interspecies reciprocity that develop into full-fledged symbioses. There are species of wrasse (a small marine fish) that have evolved such that they feed purely by eating fungus and algae off of larger fish, who offer them protection from predators in return.22 If you cruise up the Nile River, you will see crocodiles happily opening their jaws wide so that Egyptian plover birds can enter their mouths and eat bits of food stuck between their teeth. The crocodiles could easily swallow the birds in one gulp and get a nice meal out of it, but if they did, they would not get the free dental work. Similarly, you almost never see a rhinoceros in the wild that does not have an oxpecker on its back, scavenging for ticks. Scientists have documented literally hundreds of these “cleaning symbioses.” What begins as a tense reciprocal exchange leads to trust and, eventually, a symbiosis. Interspecies cooperation will be discussed in more detail in the next chapter. I mention it now only to highlight how abundant the principle of reciprocity is in nature.
The reason that reciprocity is key to understanding cooperation is that the forces of natural selection function almost exclusively at the level of the individual. A genetic basis for true selfless altruism would be hard to explain because individuals prone to helping others at a cost to themselves would suffer a disadvantage and thus see their contribution to the gene pool diminish. Selfishness beats selflessness every time. However, the concept of reciprocity creates the opportunity for cooperation and prosocial behaviors to emerge. Reciprocity means that an individual will help another for self-benefit. If helping you costs me very little now but could save my hide later, I stand to benefit from helping you. In this way, reciprocity could be favored and fostered by natural selection, and a species could become increasingly social. Importantly, it does not remove the purely selfish instincts, as we will see in later chapters.
* * *
From dogs to chimps to coyotes to Homo erectus, the survival pressures of social living have led to the evolution of cooperation. Living in cooperation, however, requires that each member play her part and consume her share. Thus, the increasing socialization of mammals has brought with it the notions of fairness and equity. Over tens of millions of years, these notions have been burned into our genetic psyche. It is part of who we are, and it is not something we had to learn for ourselves.
Hammurabi’s code is heralded as the oldest known system of laws, a pioneering document in our tradition of rules. Do not forget that there is little originality in that document. It is merely a work of translation. Hammurabi merely took the time to inscribe in the Akkadian language what had already been written eons before in the original language of justice: the As, Cs, Gs, and Ts of our DNA.
NOTE ON SCIENTIFIC SKEPTICISM
Skepticism is an essential component of science. It is the backbone of scientific thinking and crucial for the way that science produces knowledge. In common usage, the word “skepticism” implies doubt about something, founded or not. Scientific skepticism is a little different. Skepticism is simply the practice of requiring evidence for claims, and not just any evidence—verifiable, repeatable, and objective evidence. The bigger or more surprising the claim, the more evidence is required. If a claim is a direct contradiction of other claims that have been previously supported, the requirement for evidence is even greater.
A new idea in science often takes many years to gain support while it is tested experimentally again and again in many settings. Science is not dogmatic, and even the most widely accepted concept could be substantially weakened with a single convincing experiment. To paraphrase Richard Dawkins, a single fossil of a rabbit that dates to the Cambrian period would be enough to cast all of our ideas about the evolution of vertebrates into doubt.
When it comes to animal emotions, however, a different kind of skepticism abounds in the scientific community—that of unfounded and irrational doubt. Many scientists—and nonscientists, for that matter—simply refuse to believe that animals have complex emotions such as fairness (discussed in this chapter) and empathy (discussed in the next chapter). The studies and anecdotes that I detail in this book are all publicly available, have been presented at scientific conferences, and are published in the scientific literature. This means that they have overcome the burden of peer review, which exists to ensure that published studies conform to high standards of rigor, sound experimental design, and appropriate controls. Anecdotes and case studies must be presented transparently and labeled as such. Of course, opinions abound in the scientific press, but they must be supported by data.
While we obviously cannot access the inner experience of all the fair-minded animals in this chapter to know for sure what they are feeling, they certainly display the outward signs of fairness. People who refuse to believe or do not yet accept that animals experience complex emotions are increasingly forced to employ convoluted linguistic gymnastics in order to express their skepticism. Many scientists will say things like, “Dogs behave as if they experience empathy for an owner in pain.” Then, they will launch into myriad alternative explanations for each of the behaviors they do not believe are driven by complex emotions.
It is true that for each and every example in this chapter and the next one, you could come up with an alternative explanation or two. You can almost always come up with alternative explanations when you are considering scientific observations on an individual basis. However, to support an opinion that animals do not experience empathy, one would have to come up with explanations for each of the behaviors and contexts discussed in this chapter. On the other hand, I can provide one simple explanation that unites all of the examples: animals grasp the concept of unequal treatment. So it seems science favors the simplest explanation that is consistent with the facts.
Going even further, the animal-emotion skeptics resort to pointing out that we cannot know about the feelings that animals experience, so it is pointless and wrong to make claims about them. With that logic, we should not make any claims about what other humans are feeling, either. After all, how do you know that the crying man is not just acting as if he is sad?
I will concede that when the first studies and reports of animal behaviors that indicated complex emotions started to collect in the scientific literature, the community was correct in reserving judgment. We were correct in viewing these with skepticism. I mean scientific skepticism, not simply doubt. We were correct to say, “That’s interesting, but I think we need to see more data before we can conclude that these animals are really experiencing what it sometimes looks like they are experiencing.”
However, now we have more data. A lot more. As you will see in the next chapter, there is a great deal of evidence that supports the hypothesis that animals feel empathy. Do we know that they do? I suppose not. But do I really know that my dear spouse is not just a mindless automaton, a holographic projection, or a hallucination? I prefer to accept that animals really do experience complex emotions, just as I accept that my spouse really does exist and fills my life with funny and interesting conversation. To put the shoe on the other foot, I would ask such a skeptic, “We have all this behavioral evidence that animals experience joy when they play. What evidence do you have that they do not?”
Let me clarify. I am not saying that the animal experience is the same as that of humans. I am just saying that animals have an inner emotional experience. While it is technically possible that animals only behave as if they have complex emotions, it is much simpler to accept that they actually have them. All other explanations seem much more convoluted and, more important, are not supported by any evidence.
Speaking of evidence, why is the burden of proof placed on those claiming that animals do have emotions? Why is the default position that humans have emotions and animals do not? Should it not be the other way around? It seems to me that, given all of the behavioral similarities documented in this book and many others, the default position should be that all animals experience mental states that we know as emotions. In my view, the burden of proof should be placed on those who would oppose that claim.
I can only conclude that people who believe that animals have no emotional experience do so because that is what they prefer to believe for any number of reasons. I do not say this self-righteously. I am not claiming the moral high ground regarding animals and their emotions.
I am, however, claiming the scientific high ground.
Bekoff, Marc, and Jessica Pierce. Wild Justice: The Moral Lives of Animals. Chicago: University of Chicago Press, 2009.
De Waal, Frans B. Good Natured. Cambridge, Mass.: Harvard University Press, 1996.