Photograph of a chimpanzee, a member of a species in which faces are as individual as they are in humans.
In Affection and Conflict
Photograph of a chimpanzee, a member of a species in which faces are as individual as they are in humans.
Jane Goodall found that chimpanzees in the wild live affectionately together, but that they fight for status in male and female hierarchies. They have also been observed to hunt down and kill others of their own species, who live in smaller groups. Among humans more men than women commit murder; rates of murder depend not just on biology but on the kinds of societies in which we live. Muzafer and Carolyn Sherif found that boys in summer camps formed hierarchies, and when two groups were set to compete in games such as tug-of-war, a self-glorifying attitude started to occur within each in-group and derision began toward the out-group. This oppositional attitude could only be set into decline by having everyone in both groups cooperate on joint tasks.
The Chimpanzees of Gombe
We humans tend to think ourselves superior to other animals. Among our words for animal-like are “bestial” and “brutal.” Charles Darwin linked this idea to his theory of evolution. In one of his notebooks he wrote: “The devil in the form of baboon is our grandfather.”1
Our line branched off from that of the chimpanzees’ between four and seven million years ago, and we share some 98 percent of our DNA with them. Chimpanzees live more or less together in communities with up to about fifty others: adult males and females and their offspring who know their mothers but, because chimpanzees are promiscuous, don’t know their fathers.
The person who introduced us to the life of chimpanzees was Jane Goodall. In The Chimpanzees of Gombe, she describes how she and her colleagues spent many years making careful observations. Gombe, in Tanzania, is about the same size as Manhattan. It is densely forested, and has deep valleys in which streams run down to its shoreline on Lake Tanganyika.
To make her observations Goodall had two ideas without which she could not have done her research.
First, Goodall realized that she needed to spend time sitting quietly in the presence of groups of chimpanzees to accustom them to her presence. They seemed frightened at first, of this strange creature, this human, but gradually they got used to her, which enabled her to sit closely enough to them to see what they did, and to follow them where they went. She encouraged this closeness by making fruit available to the chimpanzees near her camp. After a particular group had become used to her or to one of her research colleagues, she or the colleague would be able to sit just a few meters away, observe actions and interactions, take photographs, and make notes.
The second thing Goodall did was to learn to recognize each individual and to give her or him a name. This may seem a quirk, like giving a pet a name, but it has a deeper significance. The chimpanzees are like us in that they relate to each other as individuals. You can see the face of an individual chimpanzee in the photograph at the beginning of the chapter. So, by giving the chimpanzees names and learning to recognize them individually, Goodall and her colleagues were able see who was fond of whom, who was competitive with whom, who was where in hierarchies of status, who had what kind of personality—pushy and aggressive perhaps, or retiring and reclusive.
Jane Goodall was born in London in 1934 to novelist Vanne Morris-Goodall and businessman Mortimer Morris-Goodall. Jane was always fascinated by animals. She saved up enough money so that she could live among Africa’s wildlife, and, when she was twenty-two, she had enough to travel to Kenya to stay with a friend whose family had a farm outside Nairobi. When she was there, she phoned Louis Leakey, a leading palaeontologist, and was offered a job. Leakey sent her to London to study primatology, and in 1960 Goodall returned to Africa to work on a project that Leakey suggested, to study chimpanzees in the wild. Two years later, at Cambridge, she was one of only a very small number of people allowed to enroll in a PhD program without having an undergraduate degree. In 1964, she married the photographer Hugo van Lawick, and he took photographs of the chimpanzees at Gombe. Goodall and van Lawick later divorced, and Goodall married Derek Bryceson, head of Tanzania’s national park system. He was able to protect Goodall’s research in Gombe and prevent it from becoming a destination for tourists. In her later life, Goodall has devoted herself to advocacy for chimpanzees.
Chimpanzees are often affectionate and companionable. Here’s an example:
Melissa and her daughter Gremlin have made their nests [in the trees] some 10 meters apart. Melissa’s son Gimble still feeds on msongati pods … Gremlin’s infant, Getty, dangles above his mother, twirling, kicking his legs, and grabbing at his toes. From time to time Gremlin reaches up, idly, tickling his groin … Suddenly from the far side of the valley come the melodious pant-hoots of a single male: Evered, probably in his nest too. It is Gimble who starts the answering chorus, sitting up beside Melissa, his hand on her arm, gazing toward the adult male—one of his “heroes.”2
Goodall found that chimpanzee groups were organized into hierarchies, arrangements that are accepted by everyone in the group, which allow resources to be distributed relatively peacefully. The alpha male is at the head. He wins his position by defeating a previous holder through threats, intimidation, or fighting, and he holds the position usually for several years. Other males are organized roughly in a hierarchy beneath him. Females have a parallel hierarchy.
For the most part chimpanzees eat fruit, but they also hunt small animals, such as monkeys or piglets that they happen to come across. Males are usually more involved than females in hunting. When they have been successful in a hunt, they may squabble over the food, but sometimes they share it, sometimes so that favors are returned.3 High-ranking animals obtain part of a catch, even when they have taken no part in the hunt, and usually they let only relatives and allies take shares.4 Neither the gathering of a group to eat from trees, nor this kind of sharing, is equivalent to human sharing of food.
Chimpanzees are also quite competitive. They fight a good deal, often with others who are close to them in the hierarchy, in attempts to improve or maintain status. Goodall categorized fighting into three levels. At level one is a push or a hit, or a kick. Level two is an attack. It includes dragging, pounding with a fist, and the like, and it lasts less than 30 seconds. Level three is a severe attack, like that of level two, but lasting more than 30 seconds. Goodall found that attacks (levels two and three) made up 15 percent of fights, and in a quarter of these blood flowed, or an injury was inflicted.
Goodall found that, in 4,900 hours of observing thirteen individuals over two separate years, and excluding hours of darkness or when an animal being observed was just on its own or only with dependent offspring, attacks (at levels two and three) occurred every 62 hours in males, and every 106 hours in females. One particularly aggressive alpha male managed an attack every nine hours. The least aggressive animal, a female, did not attack in 230 hours. When a fight has occurred, the animals often later get together for reconciliation, for instance with a hug. When a dominant animal is approached by an inferior after a fight, the dominant one “responds to the submissive gestures of the subordinate with a touch, a pat, or even an embrace.”5 Mutual agreement has been reached about status. The dispute is resolved.
It had been thought that we humans are the only mammals that kill members of our own species. In her 1986 book, Goodall says she was appalled to observe a group of chimpanzees going around in a gang to hunt down and kill other chimpanzees they found alone or in small numbers. What had happened was that the original community whom Goodall and her colleagues were studying had divided. At first, after the separation, the two groups met occasionally, for instance when they came to get fruit at the camp. Although some meetings between individuals were friendly, in general members of both communities were tense at these encounters.
After the split, one of the communities was substantially smaller than the other. It had just six adult males and it tended to range south of Goodall’s camp. The southern males started to avoid visiting the camp, and members of the two new communities started to avoid each other. Then Goodall and her colleagues noticed that northern males were starting to patrol, in a gang, along their borders, and then to make incursions into the southern area. On one such incursion, a group of six adult males, with one female and one adolescent male, encountered a southern male on his own. He tried to run away, but was caught by members of the northern patrol. While one male held him, other males beat him with fists for about ten minutes, and one bit him several times. Goodall says he was severely injured. He was never seen again, and Goodall inferred he had died from his injuries. Goodall and her colleagues observed that one by one all the other adults in the southern community were killed in a similar fashion, and they had no doubt that this was the intention. Adolescent females from the southern community joined the northerners.
It wasn’t that the members of the southern community were strangers. Some of them had been friends with those who had become northerners. The attacks that were observed between northerners and southerners lasted longer than any that had been seen previously within a community, and they involved tearing and biting flesh in the way that occurred when eating animals of another species. The killing groups were largely male, and their attacks were made either on individuals or on numerically weaker groups of southerners they came across during their incursions. No members of the southern community were observed making incursions into the northern area, so the conflict could scarcely be regarded as territorial. For the northerners, the southerners had become an out-group, with hostility directed to others who had become “them,” no longer “us.”
There was considerable controversy when Goodall reported lethal attacks by chimpanzees, with some people saying such attacks did not occur naturally, but were an artifact of Goodall having provided fruit for the animals at her camp. This idea has been refuted by reports from other sites where no such provisioning had been made; intercommunity killings are rare, but they do occur.6
Henri Tajfel and his colleagues have shown that the phenomenon of Us-versus-Them is very basic. In order to perform their experiments, they would assign people randomly to groups. Participants were told they were in one group or another. For instance, a coin would be tossed and, depending on the outcome, a participant would be in the heads group or the tails group. Then participants were asked to assign rewards to members of the group of “heads” and “tails,” even when they did not know who was in the group they were in (their in-group) or who was in the other group (an out-group). They gave preference to people who were members of their in-group, even when this preference had no effect on their own rewards. Daniel Yudkin and colleagues found a similar bias in punishment. Participants played an economic game in which they thought other players were or were not supporters of their favorite sports team, and in which they thought others were or were not members of their nationality. In the game, they witnessed another player stealing. They inflicted more severe punishments when they thought the perpetrator was not in their in-group.
Another set of studies was conducted by Muzafer and Carolyn Sherif, who observed groups of boys at summer camps in 1949, 1953, and 1954. The researchers wanted to understand informal groupings that would arise without external pressures. For their participants they chose boys of slightly above average intelligence aged eleven to twelve. They interviewed potential participants’ parents and teachers, and chose boys who were in good health, from well-adjusted, stable, middle-class homes. The camps to which the boys were invited were of a kind that are common for American children. The boys didn’t know each other before they arrived at the camp, and they didn’t know the purpose of the study. Members of the Sherifs’ research group took on roles as camp staff directors, counselors, and so on. The first study, in 1949, consisted of twenty-four boys at a camp in northern Connecticut. The camp was arranged in three stages.
In stage I, which lasted three days, the boys were all housed in one large bunkhouse, and they quickly formed friendships.
In stage II, the boys were assigned to two equal groups, making sure that those who had become best friends were separated. The pain of separation was lessened by taking the two groups of boys on separate bike trips and campouts, which they found exciting. Each group developed a hierarchy, with a leader, in much the same way that Goodall had recorded for chimpanzee communities. Each group gave itself a name: Bull Dogs and Red Devils. Each established a territory, developed its own customs and culture. The leader of the Bull Dogs “rose to the leadership position by his greater contribution in the planning and execution of common activities and by regulating and integrating the tasks and roles of the group members.”7 He devised and regulated tasks to improve the bunkhouse, to build a latrine, and to create a secret swimming place. He supported the other boys in the group, praised them for their work, and made sure the boys lowest in the hierarchy were included. In contrast, the leader of the Red Devils was “recognized primarily for his daring, his athletic skill and his ‘toughness.’”8
Both groups devised methods of punishment for those who did not properly carry out tasks assigned to them. For the Bull Dogs, punishments included moving large stones from the secret swimming place. Only once was the leader of the Bull Dogs seen to threaten another boy, and he did this verbally. The other boys in the group thought that generally he was “fair.” By contrast, methods used by the leader of the Red Devils included threats and “roughing up.”
The two groups were different in their organization. The Bull Dogs were compact, without much emotional distance between boys of higher and lower status. The Red Devils had a much steeper hierarchy. Their leader had a great deal of prestige but was cliquish, with three close lieutenants to whom he gave favors, and with whom he preferred to spend his time. Boys at the bottom of the hierarchy were emotionally distant, and sometimes were bullied.
After five days in which the boys had been separated into the two groups, approximately 90 percent of friendships of the boys had come to be within their own group. In each group, there was a great amount of affection, loyalty, and solidarity. A few boys who wanted to maintain friendships formed in stage I, with boys who were now in the other group, were called traitors. When the groups met, relationships were generally friendly, with any unfriendly trends that occurred being referred to as “play.”
Stage III involved competitions between the groups. These included baseball, tug-of-war, and football, with points being awarded for each, and cumulative points contributing to coveted prizes of a hunting knife for each member of the winning group. As the competitions began, a proud, self-glorifying attitude arose within each group. The boys believed their own group to be strong and fearless. Accusations of the other group began. Within the group there was closeness and inter-reliance, toward the other group there was anger and contempt, with fights starting to break out.
When, in stage III, relations between the two groups had deteriorated, the researchers became alarmed and tried to find ways of improving them. One year, they had the idea of arranging for the two groups to share a meal together. But one of the groups arrived before the other and ate most of the food. When the other group arrived they were angry, and a fight broke out. The meal was abandoned. The method the Sherifs finally hit upon to reduce conflict between groups was cooperation in joint projects. In one, the researchers arranged for the water supply into the camp to be cut off. The boys had to cooperate to search the long pipeline that brought water into the camp, and to repair it. In another, when the boys were hungry, it was arranged that the truck that was used to go into town to get food failed to start. The boys decided that they needed to work together and use a rope (which had been used for tug-of-war) to pull the truck so that it could be put into gear in order to start it. Although hostilities did not cease immediately, they were much reduced by the joint projects. The results of cooperative activities for one year are shown in figure 19.
Figure 19. Hostility and reconciliation in the studies of Muzafer and Carolyn Sherif: percentages of boys in each group who thought all those in the other group (rather than some or none) were cheaters, sneaks, and the like, at the end of stage III, before and after cooperative activities. Data source: Sherif, M. (1956). Experiments in group conflict. Scientific American, 195 (November), 54–58. Drawn by Keith Oatley.
Human Killers
Among humans there exists not only a problem of Us-versus-Them, but also of Male-as-compared-with-Female. Martin Daly and Margo Wilson have found that many more men than women kill unrelated people of the same sex; for instance, in such cases, male-male killing was found, in England and Wales, to be twenty-three times as likely as female-female killing, and in Canada, forty times. The populations of perpetrators and victims are similar, and the peak age for being a killer is the mid-twenties.
For humans, the body type of females is more basic than that of males. A geneticist who remains nameless has said that the male body type is “customized.” He was drawing a comparison with the way some people buy an automobile, then customize it to make it faster and stronger.
Daly and Wilson point out that, on the subject of killing others, a purely biological explanation won’t do. Societal factors play a part, as we can see from murder rates that vary by country, with same-sex murders being fifty-eight times more frequent in Detroit, United States, than in England and Wales. More likely, say Daly and Wilson, the male proclivity to homicide is a hybrid of biological and social factors, with males being in competition with each other, including competition for sexual partners. Unmarried males are three or more times more likely than married males to kill other males.
A large societal component has also been found by Steven Pinker. He found that rates of homicide in proportion to the size of populations, worldwide, both in groups (as in wars) and among individuals (as in murder), have been in decline. Among reasons for a ten- to fifty-fold decrease of violence in Europe since medieval times to the present has been the set of civilizing processes described by Norbert Elias. He showed that from the thirteenth century onward, starting among groups of aristocrats as they ate together, especially in the presence of women, lack of self-control and displays of violence became unacceptable. To behave without consideration for others became shameful. At the same time, acts of feuding and vengeance, which were personal, began to be replaced by processes of justice administered by the state. People’s preference for reading and watching stories of detection and court trials suggests that we are still very interested in these issues.9
Since the time of the split between the line that led to chimpanzees and the line that led to humans, there have been twenty or more other hominid species who were not our direct ancestors.10 The species that became extinct most recently is that of the Neanderthals, who lived in Europe until our ancestors colonized the area, some 30,000 years ago. Paul Mellars has inferred that groups of the two populations met and there was conflict. Humans had better technology and better skills of cooperation than the Neanderthals, and these gave our ancestors the advantage in carrying out aggressive intentions. With Jennifer French, Mellars has also found that with the colonization of Europe, our human ancestors came to outnumber Neanderthals by ten to one, and this too contributed to the Neanderthal extinction. There is evidence for some interbreeding, and it is estimated that about 1 percent of human genes derive from the Neanderthals, but as a species, they became extinct.11
Knowing this, and knowing what we do with our proclivity for Us-versus-Them, it seems likely that our human ancestors were responsible, at least in part, for eliminating other hominid groups. We continue to see the anti-social goal of such elimination in war, in genocide, in colonization, in class struggle. But then, as Steven Pinker has found, there are better angels in our nature. Despite two terrible world wars of the twentieth century, over time our proclivities to kill each other have diminished.
