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competition or cooperation

The social intelligence hypothesis emphasizes competitive social interactions.

While it is certainly true that our competitive interactions are the most complex among mammals, it is our cooperative social interactions that most distinguish us from other mammals. There is a computational component to our cooperation, in communicating our goals and coordinating our activities, for example—whether in constructing a house or playing a game. But before there is a way to get things done collectively, there must be a will to get things done collectively. That is, the proper motivation must be in place. Undergirding this motivation are emotional predilections. According to the self-domestication thesis, alterations in emotions—primarily fear and aggression—were the prime movers in human cognitive evolution. It is this reduced fear and aggression in the presence of our fellow humans—in a word, tameness—that is the foundation of our cooperative interactions.

It will be useful at this point to compare humans and chimpanzees for their cooperative inclinations. Michael Tomasello and his associates at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, conducted much of the research to which I will refer. Tomasello distinguishes three key features of cooperative interactions. First, the participants must share a joint goal and a commitment to that goal. Second, the participants must be motivated to fluidly adopt complementary roles in achieving that goal. Third is the criterion of mutual aid or support, which means that a participant must be not only prepared to perform his particular role, but also willing to help a fellow cooperator fulfill her role if necessary.

Many primates engage in shared group activities, but few such activities meet these criteria for truly cooperative behavior. The group hunting behavior of chimpanzees is often touted as an example of cooperation in which one individual, called the “driver,” chases the prey in a certain direction; others, called “blockers,” prevent the prey from changing direction; and finally, “ambushers” silently move in for the kill. But as Henrike Moll and Tomasello convincingly argue, the terms “driver,” “blocker,” and “ambusher” may well be anthropomorphic over interpretations of what actually goes on in a chimpanzee hunt.

The group hunt may be accomplished without any shared goal or plan; rather, each individual simply chases the prey from its particular position at that moment. This position is far from prearranged; rather, each chimp simply adopts whatever spatial position is most immediately available. The chimps are certainly responsive to each other’s behavior during the hunt, but they lack the “jointness”—or, more technically, “shared intentionality”—that characterizes true cooperation. Laboratory experiments support this leaner interpretation of chimpanzee hunting behavior.

Juvenile human-reared chimps were first tested for their ability to cooperate with humans in a problem-solving game and then in a purely social game. In the problem-solving game the chimps did quite well, but only when the human was constantly present. After any interruption the chimps failed to reengage the human partner to resume the game. In the purely social game, the cooperation never even got off the ground. For humans (18–24 months of age), the results were quite different. They cooperated enthusiastically in both the problem-solving and the social games, and when the adults stopped participating, they sought strenuously to reengage them. So, by the age of 18 months, human infants are eager to jointly commit to a shared goal—the first criterion of cooperative behavior. No such commitment can be found in chimpanzees. Other experiments have shown that human infants but not juvenile chimpanzees also meet the second (reciprocity) and third (mutual aid) criteria as well.

Cooperation requires communication. Human communication via language is, of course, nonpareil. But humans are also superior to chimpanzees with respect to nonlinguistic communication of cooperative intent. Infants who have not yet acquired language skills outperform much older chimpanzees in cooperative communication. For instance, though chimpanzees frequently gesture in a variety of ways, there is not one documented case of a chimpanzee pointing for another to direct its attention. By 12 months of age, human infants point to inform others not only of what the infants want but also of things that the infants believe the adults want. By this young age, human infants have a motivation to inform others for nonutilitarian reasons. Chimps show no interest in sharing information in this way, whether with humans or with other chimps.

So, during the last 5–7 million years, the psychology of humans and chimps has diverged considerably. Was this evolutionary divergence primarily emotional or computational (social intelligence)? This question’s premise is actually a false dichotomy; obviously, both emotions and intelligence, as well as emotional intelligence, were altered in humans relative to chimps. But according to the self-domestication hypothesis, the psychological change that got the ball rolling was emotional. At some point in human evolution, some individuals became more tolerant of each other and were less aggressive and fearful in each other’s presence. In this respect our evolution is convergent with that of the dog and some of the other domesticated species described in this book.

Bonobos are much more closely related to chimpanzees. Brian Hare and his colleagues conducted an interesting series of experiments on bonobos and chimps in which they tested first their social tolerance and then their ability to cooperate to accomplish a joint goal. Tolerance was tested in the context of joint feeding, which can be emotionally fraught, given the temptation to selfishly hoard or monopolize all of the calories. When presented with fruit in a single dish, chimps did succumb to this temptation. Bonobos, however, had no problem sharing, diffusing the tension with their characteristic sexually charged play. The bonobos were more tolerant of each other and seemingly less stressed than the chimpanzees.

Next, pairs of bonobos and chimps were tested for their ability to cooperate to accomplish a common goal. They were required to jointly pull a rope to attain food dishes. When it was obvious that only one dish contained food, chimps would not cooperate and hence obtained no food. Bonobos, however, cooperated quite effectively to obtain the food, which they then shared. If both dishes had food and hence the food could not be monopolized, bonobos and chimps did equally well on the rope-pulling task. In general, chimps do as well as bonobos in cognitive tasks in competitive situations. Bonobos outperform chimps when cooperation is required. Moreover, bonobos, like humans but unlike chimpanzees, will share food with complete strangers. These experiments demonstrate that the cooperative superiority of bonobos is related to their higher social tolerance. Increased social tolerance is characteristic of domesticated mammals from rats to dogs.

domesticated domesticators

Given the state of our current knowledge, it is much too early to pronounce a verdict on either the weak or strong versions of the self-domestication hypothesis. But as a sort of organizing principle, a stimulus for future research, the self-domestication hypothesis provides a useful counterpoint to traditional views of human evolution in two important respects. First is the shift in focus from our so-called higher cognitive faculties and their neural substrates to parts of the brain we share with all mammals that undergird our emotional behavior. Second is the emphasis on our cooperative, or prosocial, side—rather than, as has been the focus heretofore, our competitive interactions—in driving the evolution of social behavior. For it is our unmatched ability to cooperate for shared ends that most distinguishes us from other primates. And it is through our cooperative endeavors that we have become a force of unprecedented power among any life-forms to have ever evolved. While all living things have the capacity to change their environment, our ability to do so is unmatched and ever accelerating, to the point that we humans have collectively constructed the environment in which most future evolution will occur. The animals we domesticated were in the vanguard of a new phase of life on earth: the Anthropocene.

Culture itself is not an individual property; it is a collective property of a society of individuals. By “society” I mean a group of individuals whose activities are integrated and coordinated. This is another fundamental way in which cultural evolution differs from biological evolution. It can’t be emphasized enough how the collective nature of human activity has driven human ascendancy. Had early humans been 10 times smarter than us, but solitary, we would never have become domesticators. Whether or not we came by them by way of self-domestication, the emotional alterations that made possible our hypersociality were even more important than our intelligence in our rise to the domesticator state.

Let’s now relate these facts about cultural evolution to the question with which we began this chapter: What caused humans to become culturally modern and ultimately domesticators? We begin with the latter part of the question.

The transition from hunting and gathering to farming was a seminal event in human evolutionary history. It was not the discovery of some lone genius that possessed a unique cognitive mutation. Farming was, rather, the result of collective cultural explorations—some say in response to deteriorating conditions for hunting, while others emphasize enhanced conditions for gathering and plant management. In either case, human societies—first in the Near East, later in China and elsewhere—that had acquired through long association intimate knowledge of local plants began to use this collective knowledge to manage some of these plants, such as wheat (and other grasses such as maize, barley, rice, and rye), legumes (peas and beans of various sorts), gourds, and fruits such as figs, in order to guarantee a more constant and voluminous food supply. 

Domesticated: Evolution in a Man-Made World, is not an easy book. Francis doesn’t baby the reader. Thank you. He challenges our reading skills, our vocabulary, and our understanding of the world. That’s what every good book does.

Domesticated: Evolution in a Man-Made World, Richard C. Francis, W. W. Norton, 2015