Human the Hunted_: 'Human the Hunter' theory is debunked

Professor RW Sussman MAN THE PEACE-LOVING HIPPIE? The blood-bespattered, slaughter-gutted archives of human history from the earliest Egyptians and Sumerian records to the most recent atrocities of the Second World War accord with early universal cannibalism . . . and with worldwide scalping, headhunting, body-mutilating and necrophilic practices of mankind in proclaiming this common bloodlust differentiator, this predaceous habit.79 Ouch! Given the above scenario laid out by Raymond Dart, one can only blush at the legacy we've allegedly inherited. The trail seems to lead from meat-eating to hunting, meander into cannibalism, and ultimately dive inexorably into a whole slew of repulsive activities. But, as we keep returning to after every misanthropic description, are views taken from a Man the Hunter tableau supported by any scientific evidence? When the 2006 American Association for the Advancement of Science (AAAS) meeting convened in St. Louis, Missouri, we participated in a symposium bringing together researchers from diverse fields (primatology, sociocultural anthropology, zoology, paleontology, psychiatry, psychology ,neurobiology, and genetics) to consider substantive evidence about violence versus cooperation as hard-wired human behaviors. Along with other scientists, we synthesized current research supporting the behavioral, hormonal, and neuropsychiatric evolution of human cooperation. To assess human behavior, researchers look at our primate roots where sociality may have its origin in the general benefits of mutual cooperation, strong mother-infant bonds, and the evolution of an extended juvenile period in which developing young are dependent on other group members. Naturally occurring opiates in the brain that have effects not unlike the restfulness and lessening of unease attained through opium-based narcotics (but without highs, withdrawals, or addiction) may be at the core of innate cooperative social responses.80 These could finally explain the evolution not only of cooperation among non-related humans and non-human primates but also of true altruistic behavior. Going one step further, Marc Hauser, professor of psychology, organismic and evolutionary biology, and biological anthropology at Harvard, believes there is evidence of a true moral toolkit in the human brain, a genetic mechanism for acquisition of moral rules.81 Researchers have, in fact, identified a set of neuroendocrine mechanisms that might lead to cooperative behavior among related and non-related individuals. In experiments using magnetic resonance imaging, or MRI (a technique that employs radio waves rather than radiation to elucidate deep structure), mutual cooperation has been associated with consistent activation in two areas of the brain that have been linked with reward processing--specifically, the anteroventral striatum and the orbitofrontal cortex. James Rilling, a neurobiologist at Emory University, has proposed that activation of this neural network positively reinforces cooperative social interactions.82 Even more compelling, the strength of the neural response increases with the persistence of mutual cooperation over successive trials; it is cumulative and self-reinforcing. Activation of the brain's reward center may account for why we tend to feel good when we cooperate. Both locations in the brain linked with reward processing are rich in neurons that respond to dopamine, the neurotransmitter known for its role in addictive behaviors. The dopamine system evaluates rewards--both those that flow from the environment and those conjured up within the brain. When the stimulus is positive, dopamine is released. In experiments with rats in which electrodes are placed in the anteroventral striatum, the animals continue to press a bar to stimulate the electrodes, apparently receiving such pleasurable feedback that they will starve to death rather than stop pressing the bar.83 As Dr. Gregory Berns, an Emory University professor and one of the authors of a 2002 report in the psychiatric journal Neuron puts it: "In some ways . . . we're wired to cooperate with each other."84 Another physiological mechanism related to friendly affiliation and nurturing is the neuroendocrine circuitry associated with mothering in mammals. Orchestrating the broad suite of these bio-behavioral feedback responses is the hormone oxytocin. Oxytocin has been related to every type of animal bonding imaginable--parental, fraternal, sexual, and even the capacity to soothe one's self. Researchers have suggested that although oxytocin's primary role may have been in forging the mother-infant bond, its ability to influence brain circuitry may have been co-opted to serve other affiliative purposes that allowed the formation of alliances and partnerships, thus facilitating the evolution of cooperative behaviors.85 Results from both behavioral endocrinology and functional MRI studies by University of Wisconsin psychologist Charles Snowdon and colleagues on cotton-top tamarin monkeys reveal other hormonal mechanisms critical to cooperation and affiliative behavior.86 Among these small South American monkeys, males and other helpers, such as older siblings, provide essential infant care. Elevated levels of the hormone prolactin, usually associated with lactation, may be the impetus behind maternal caregiving exhibited by males and siblings. Snowdon has also found correlations of oxytocin and prolactin levels with amounts of friendly social behavior between one adult and another. His experiments indicate that high levels of affiliative hormones could result in good-quality social interactions that suggest a reward system for positive behavior.87 Many cooperative behaviors observed in primates can be explained by individual behaviors that benefit several group members.88 Coordinated behaviors such as resource or range defense, cooperative foraging and food harvesting, alliance formation, and predator vigilance and defense can be explained in terms of immediate benefits to both the individual and other group members. Even if the rewards for these behaviors are low level, we should expect cooperation to be common. Thus, many types of social interactions may be best understood in terms of a nonzero- sum game, with multiple winners. Low-risk coalitions in which all participants make immediate gains are widespread among primates89 and may explain why nonhuman primates live in relatively stable, cohesive social groups and solve the problems of everyday life in a generally cooperative fashion. Charles Darwin had this idea long before scientific studies of animal behavior, primatology, or cooperation when he noted that natural selection would opt for "the feeling of pleasure from society."90 Even though most nonhuman primates are highly social, investigations into the evolution of primate sociality have tended to focus on aggression and competition instead of cooperation. However, many results from behavioral, hormonal, and brain imaging studies offer a new perspective about primates and their proclivities toward cooperation, sociality, and peace. For example, after 16 years of research on the behavior and ecology of wild savanna baboons, well-known primatologists Joan Silk, Susan Alberts, and Jeanne Altmann concluded that social integration even enhances reproductive capabilities in female baboons: "Females who had more social contact with other adult group members and were more fully socially integrated into their groups were more likely than other females to rear infants successfully."91 Frans de Waal, a chimpanzee researcher at Emory University, contends in his book Primates and Philosophers92 that chimp societies emphasize reconciliation and consolation after conflict; his 40 years of primate behavior observations have documented that concern for others is just natural conduct for our closest primate relatives. In a nutshell social animals appear to be wired to cooperate and to reduce stress by seeking each other's company.93 If cooperation and physical proximity among group-living animals are rewarding in a variety of environmental and social circumstances and if physiological and neurological feedback systems reinforce social tolerance and cooperative behavior, then social living can persist in the absence of any conscious recognition that material gains might also flow from mutual cooperation. Based on the latest research, friendly and cooperative behaviors provide psychological, physiological, and ecological benefits to social primates which are positively reinforced by hormonal and neurological systems. But, what about violence and war? Why is there an acceptance that humans are innately aggressive and that we characterize our aggressive feelings through violent actions? The general primate physiology does not support this view and leads instead to a belief that cooperation is innate to humans. Why the disconnect? Sometimes putting things in perspective helps. There are more than six billion humans alive today-- all are social animals having constant hour-by-hour interactions with other humans. And we're willing to bet that the overwhelming majority of our six billion conspecifics are having days, weeks, even entire lives devoid of violent interpersonal conflicts. This is not to naively underplay crimes, wars, and state-level aggression found in modern times, but it puts them in the domain of the anomalous. Who reads a news report of an outbreak of terrible ethnic violence or genocide and thinks "What's so unusual about that?--perfectly normal, happens every day to everyone." War happens . . . crime happens, but what is the context in which they happen? Why do murder rates vary so greatly from country to country, from culture to culture? Are war, crimes, and violence the genetic, unalterable norm . . . or are they specific to stresses that occur when too many people want too few resources? Following his exhaustive examination of ethnographic research on modern societies ranging from nomadic foragers to urban industrialized societies, Douglas Fry, an anthropologist at Åbo Akademi University in Finland and the University of Arizona, documented the human potential for cooperation and conflict resolution in a groundbreaking volume entitled The Human Potential for Peace: An Anthropological Challenge to Assumptions about War and Violence.94 Fry stresses that virtually all early studies defining man (only men were defined!) by his capacity for killing appear to be flawed. Sit down and prepare to be shocked with welcome relief when you read Fry's statement: "War is either lacking or mild in the majority of cultures!"95 Counter to assumptions of hostility between groups and among individuals and recurring warfare over resources, the typical pattern is for humans to get along rather well, relying on resources within their own areas and respecting the resources of their neighbors. After an examination of the actual ethnographic information on nomadic foragers, Fry found the proposition that human groups are pervasively hostile toward one another is simply not based on facts but rather on "a plethora of faulty assumptions and overzealous speculation."96 He points out that "[c]onflict is an inevitable feature of social life, but clearly physical aggression is not the only option for dealing with conflict" (author's emphasis).97 Behaviors for conflict management catalogued in major cross-cultural studies include (1) avoidance (disputants cease to interact), (2) toleration (the disputed issue is not acknowledged by the concerned parties), (3) negotiation (mutually acceptable compromises are created), and (4) settlement (a third party deals with the problem, as in mediation, arbitration, or adjudication-- approaches very common in the U.S. and other industrialized nations). Individuals and whole societies deal with conflicts in non-violent ways. But these commonly used approaches are not very high profile or noticeable on the media radar. "PEACE BREAKS OUT BETWEEN TWO VILLAGES IN SOUTHEAST ASIA BECAUSE DISPUTANTS DECIDE TO TOLERATE EACH OTHER!" or "AUSTRALIAN OUTBACK RIFE WITH AVOIDANCE AFTER PERCEIVED INSULT" are not the typical headlines we read. Fry found that only one approach to conflict--unilateral self-redress (defined as one disputant taking unilateral action in an attempt to prevail or punish another)-- might (our emphasis) involve physical aggression. He summarized his findings by acknowledging the human propensity to behave assertively and aggressively, but adamantly stating that just as inherent is the human propensity to behave prosocially and cooperatively, with kindness and consideration for others. Indeed, Fry's work has convinced him that the very existence of human societies is dependent on the preponderance of prosocial tendencies over assertive and aggressive ones. We aren't trying to ignore the role of aggression and competition in understanding primate and human social interactions. Our perspective, however, is that affiliation, cooperation, and social tolerance associated with long-term mutual benefits form the core of social group living. Our earliest ancestors lived in a world populated by large, fearsome predators. Strong indications from the fossil record and living primate species lead to the conclusion that hominids were regularly hunted and required social organization that promoted inconspicuous behaviors, minimal internal conflicts, and coordinated vigilance.98 Ask yourself, in this prehistoric world of predators what would have been the best strategy to avoid being eaten: Conspicuous, violent interpersonal conflicts? Or high levels of cooperation and reciprocity to facilitate as inconspicuous a presence as possible? Now, what about chimps, warfare, and the demonic male theory? How do they stand up in relation to all this new evidence on cooperative behavior? As we said in opening this chapter we're finding that Man the Hunter as a paradigm does not die easily. Well, the same can be said for its first cousin, the demonic male theory. Richard Wrangham has attempted to address some criticisms of the theories he proposes in his book Demonic Males: Apes and the Origins of Human Violence, coauthored with Dale Peterson.99 In striving to support the demonic male theory Wrangham and his students cite a growing number of observed or suspected cases of lethal attacks by chimps on chimps at a number of different research sites,100 although the context of these attacks is rarely described and the fact that each of the study sites suffers intense interference from habitat encroachment, introduced diseases, hunting and poaching pressure, food provisioning, and/or constant surveillance by primatologists is not addressed. 101 More evident, however, in the follow-up to Demonic Males is a development of the theoretical argument purporting to explain chimp and human violence in three ways. First, a belief that warfare in humans and violent, deathly attacks in chimpanzees are examples of a phenomenon Wrangham labels "coalitionary killing." According to his explanation, adult male chimps and humans collaborate to kill or brutally wound other adults: "The ancient origin of warfare is supported by . . . evidence that . . . chimpanzees and humans share a common ancestor around 5-6 mya."102 Secondly, Wrangham believes the principal adaptive explanation linking coalitionary killing in chimpanzees and humans is the "imbalanceof- power" hypothesis. Accordingly, chimpanzee males will attack other groups if they outnumber them and have a low risk of injury to themselves. Because of the complexity of modern warfare, these types of lethal raids can be seen more readily in humans in "primitive" warfare among "pre-state" societies.103 Finally, the long-term evolutionary explanation of coalitionary killing is a "dominance drive" that favors unprovoked aggression by the opportunity to attack at low personal risk. The dominance drive is related to increased genetic fitness, allowing the killers to leave more of their dominant-killer genes to the next generation.104 Wrangham assumes certain behaviors resulting in conspecific killing among ants, wolves, chimpanzees, and humans (especially those in "primitive, pre-state" societies) are similar phenomena. Presumably they have the same biological bases and motivations, and are driven by the same underlying natural causes. He gives these behaviors the label "coalitionary killing" and, in creating a name, he creates a phenomenon. When comparisons are made between human and animal behavior, and it is assumed that behaviors that are similar in appearance have similar functions and evolutionary histories, a basic principle of biology is being violated. Form alone does not provide information about function nor shared genetic or evolutionary history. Referring to "rape" in dragonflies, "slavery" in ants, or "coalitionary killing" in chimpanzees and humans may sound like science but, to paraphrase Jonathan Marks's reprimand, science is concerned with biological connections, not metaphorical descriptions.105 Another aspect of the demonic male theory is the argument that an imbalance of power must be an incentive to coalitionary killing. Are we to suspect that whenever a group of chimpanzees or humans perceives weakness in an individual or another group, they will attack and kill? In fact, neither chimpanzees nor humans attack in all circumstances of imbalance-of-power, and coalitionary killing is extremely rare in both species. (Remember Douglas Fry's findings that there are many ways to handle conflict--avoidance, toleration, negotiation, settlement?) One major set of questions pervades all of the observations of lethal chimpanzee attacks: What is the underlying motivation and what types of stressors prompt lethal attacks to occur in some cases and not in others? Also, in chimpanzees, how much does severe habitat encroachment, harassment, provisioning, crowding, hunting, and even constant surveillance affect the lives of these highly intelligent animals who are now in danger of extinction in almost every forest in which they occur? And, how do many of these same stressors in the modern world affect humans? The third part of the demonic male theory--that dominance drives are present--needs clarification. Robert Hinde, one of the most respected animal behaviorists of our time, has considered the concept of psychological and behavioral "drives" at length. He emphasizes that the word itself can make for difficulties because it has been used in so many different ways. Where measures of behavior can be directly correlated, such as drinking leading to a cessation of thirst, the proposition of an intervening drive variable may be a valuable tool for research. However, when correlations between behaviors are not perfect, Hinde cautions, "such a concept is misleading and can be a positive hindrance."106 The use of the concept of drive in relation to the extremely complex set of behavioral and contextual phenomena involved in dominance seems to us to be entirely inappropriate. CONVENTIONAL WISDOM AS SCIENCE How do theories or new paradigms in science get accepted or, on the other hand, ignored? Unfortunately, the answers to this question may turn out to be much more political than scientific. In 1962 a philosopher of science named Thomas Kuhn wrote a classic book, The Structure of Scientific Revolution. In it he argued that scientists examine the evidence related to their questions and come up with the most parsimonious explanation (or theory, or paradigm) that fits the data and techniques currently available at the time. However, the evidence is also filtered through a scientist's own background and theoretical orientation, by his or her world view and cultural milieu. Changing currently popular, engrained paradigms, those that have become "conventional wisdom" like the Man the Hunter theory, is very difficult especially if the theory also fits conventional cultural views of the world. Scientists, like most people, are generally conservative in their ability to adopt new paradigms. Once a paradigm becomes established within a scientific community, most practitioners become technicians working within the parameters of the theory but rarely questioning the validity of the theory itself. In fact even questioning the theory is often thought of as unscientific because the new theory and the old are incompatible and the internal logic of each paradigm differs. Proponents of each paradigm are often talking past one another--speaking a different language. As expressed by Shirley Strum in her landmark book Almost Human, in a passage describing her efforts to get primatologists to accept her observations that aggression was not as pervasive or important an influence on the evolution of baboon behavior as had previously been thought: "In science, according to Kuhn, ideas do not change simply because new facts win out over outmoded ones. Many more social, cultural and historical variables make up the complete picture. Since the facts can't speak for themselves, it is their human advocates who win or lose the day."107 So, yes, science is a matter of accumulating better and better evidence to fit a theory . . . or of finding that both old evidence and new evidence are better accommodated by a completely new theory. And, in the end, even with new evidence and a better way of explaining it, ultimately, the politics of science must take its course. It is up to the audience to weigh the evidence. Discrepancies among the theories and the evidence must be evaluated. Once these discrepancies are seen to be overwhelming, the new paradigm will be accepted in favor of the old. Kuhn was not without a sense of humor, for as his friend, the renowned social anthropologist Clifford Geertz notes, Kuhn had an embroidered motto hanging in his house which stated "God Save This Paradigm."108 Science is not always truth. Science is just the best way to answer a particular question given the available evidence and technology at a particular time and place. At this time and place, we believe Man the Hunted as a paradigm of early human evolution best fits the currently available evidence. Future evidence, nonetheless, could prove us wrong; we can only wait to see what unfolds. REALLY OUR LAST WORDS There's little doubt that modern humans, particularly those of us in Western cultures, think of ourselves as the dominant form of life on earth. And we seldom question whether that view also held true for our species' distant past (or even for the present, outside of urban areas). We swagger like the toughest kids on the block as we spread our technology over the landscape and irrevocably change it for other cultures and species, aware in a cursory way that we may cause our own demise in somewhat record time but unwilling to stop. Current reality does appear to perch humans atop a planetary food chain. The vision of our utter superiority may even hold true for the last 500 years, but that's just the proverbial blink of an eye when compared to the seven million years that our hominid ancestors have wandered the planet. We like to envision a less-powerful inauguration of our species. Consider this image: smallish beings (adult females weighing maybe 60 pounds, males heavier) with a rather unimpressive brain-to-body ratio, possessing the ability to stand and move upright. Basically, beings who spent millions of years as a primate meal walking around on two legs. (Rather than Man the Hunter, we may need to see ourselves as more like Bipedal Protein Pops.) Our species began as just one of many that had to be cautious and resourceful, depending on other group members when danger reared its head. We were quite simply small beasts within a large and complex ecosystem. Is Man the Hunter a cultural construction of the West? Belief in a sinful, violent ancestor does fit nicely with Christian views of original sin and the necessity to be saved from our own awful, yet natural, desires. Other religions don't necessarily emphasize the ancient savage in the human past; indeed, many modern-day hunter-gatherers, who have to live as part of nature, hold supernatural beliefs in which humans are a part of the web of life, not superior creatures who dominate or ravage nature and each other. Think of Man the Hunted, and you put a different face on our past. The shift forces us to see that for most of our evolutionary existence, instead of being the toughest kids on the block, we needed to live in groups (like most other primates) and work together to avoid predators. Thus an urge to cooperate can clearly be seen as a functional tool rather than a Pollyanna-ish nicety, and deadly competition among individuals or nations may be highly aberrant behavior, not hard-wired survival techniques. The same aberrance is true of our destructive domination of the earth by technological toys gone mad. Raymond Dart declared "the loathsome cruelty of mankind to man is explicable only in terms of man's carnivorous and cannibalistic origin."109 While Dart may have equated predators and their carnivorous eating habits with cruelty, predation is just a way of getting food, not a cruel thirst for blood. But, forgetting Dart's unscientific subjectivity, if our origin was neither carnivorous nor cannibalistic, we have no excuse for our loathsome behavior. Our earliest evolutionary history is not pushing us to be awful bullies. Instead, our millions of years as prey suggest that we should be able to take our ancestral tool kit of sociality, cooperation, interdependency, and mutual protection and use it to make a brighter future for ourselves and our planet. We evolved as a mainly plant-eating species that also ate some animal protein collected opportunistically. But this latter activity did not make us a predator or a scavenger. We hunted but were not hunters, and we scavenged but were not scavengers. We are neither naturally aggressive hunters and killers nor are we always kind and loving. Humans have the capacity to be both. It is what we learn and our life experiences, our world view, and our culture that have the greatest influence on our behavior, even how we react to stress. That is exactly why it is necessary to comprehend that we have not inherited a "propensity" to kill derived from our hunting past. We are no more born to be hunters than to be gardeners. We are no more inherent killers than we are angels. Humans are what they learn to be. We're making the statements above with the intention they will be our last words on the subject of Man the Hunter versus Man the Hunted. (Nevertheless, like an '80s rock band who vow there'll be no more tours, but find the lure of going on the road too great to resist . . . we might be persuaded to sing again!) 286