Scans from THE DARK SIDE OF MAN: Tracing the Origins of Male Violence, by Michael P. Ghiglieri; Perseus, 1999; http://www.amazon.com/Dark-Side-Man-Michael-Ghiglieri/dp/0738203157

[p. 71] One trait chimps, bonobos, and humans share is the retention of males. Unlike nearly every other social species of mammal, these societies generally retain their males. Meanwhile, females marry into new groups. Anthropologist Carol Ember clarified this pattern by surveying 179 hunter-gatherer societies. She found that only 16 percent of these societies retained their young women more than their young men. Chimp and bonobo social groups also keep their males but transfer their females. Gorillas do the same, although only a few males stay with their fathers. In contrast, orangutans (and almost all other primates) disperse all their males and none of their females. This pattern is significant because this one evolutionary event in the common ancestor of chimps, bonobos, and humans—the retention of males—set the stage for cooperative ape warriors.

[pp. 172-177] One big reason for those chimps’ community to fission into smaller parties is ecology. Sixty percent of a chimp’s diet consists of ripe fruit. Yet fruit is often so hard to find that wild chimps are drastically underweight compared to captive ones. Nor do enough huge fruit trees exist for all fifty or so chimps of a community to travel together and still get enough to eat. In any tree, the least dominant chimps, females in particular, lose in competition over what little fruit exists. Here again, however, males place solidarity ahead of calories. Despite the importance of a square meal, when approaching big fruit trees, males at Gombe and Kibale—but not females—have been observed pant-hooting loudly and drumming tree buttresses with their feet in a wild tattoo resounding through the rain forest for up to a mile. This bedlam attracts other chimps, who share the food of the calling males. This cooperative “food calling” pays off in three selfish ways for the males who called: by facilitating mutual grooming to rid them of parasites, by adding more male companions for safer territorial patrols, and by being able to mate with a female arrival. It also pays off in inclusive fitness by helping all relatives within earshot to achieve better nutrition. All of this, incidentally, is gained at a low cost because males usually call at trees big enough to feed all comers. By contrast, a female would gain nothing by food calling, because males habitually usurp the best feeding spots. And, to add insult to injury, she would be cheated by arriving males, who would not groom her after she groomed them.

Chimps typically travel in groups of two to six adults, but scarcity of food often forces them to go it alone. That they travel together anyway whenever they can leads us to ask the biggest question in social

Pieces of this puzzle fell into place in the early 1970s. The process began after Jane Goodall stopped her eight-year program of giving Gombe chimps six hundred bananas a day to habituate them to human observers and to keep them nearby. Her study community split into two factions. The biggest, the Kasakela community of thirty-five apes, stayed in the north. The Kahama faction of fewer than fifteen chimps went south. Within a year or two, the Kasakela males forayed south to the Kahama Valley in sortie after sortie, during which they killed at least five of the seven Kahama. males (the last two vanished due to causes unknown). They likely also killed two of the old females. These gang killings were at least as brutal as the one described at the beginning of this section. Males stomped on, twisted, bit, yanked, dragged, gouged, pounded, dismembered, and threw boulders at their outnumbered opponents with such fierce and deliberately lethal aggression that Goodall admitted, “If they had had firearms and had been taught to use them, I suspect they would have used them to kill.”

But these killer chimps were neither an anomaly nor unique to Gombe. Chimps in the Mahale Mountains (less than one hundred miles south of Gombe) launched a war a decade later. Toshisada Nishida and his colleagues concluded that males of Nishida’s huge M-Group (more than eighty chimps) systematically stalked and murdered the six adult males of the smaller, neighboring K-Group, which contained twenty-two chimps at the onset of hostilities. Their violence, too, was shockingly brutal, premeditated, and deliberately lethal.

In Gombe and Mahale, after all the adult males in each vanquished community had been killed and all the adolescent males had sickened and died, seemingly from depression, the young females shifted their allegiance and home ranges and mated with the victorious males. The victors instantly expanded their territories to include part (Gombe) or most (Mahale) of the territories of the dead males. Both defeated communities ceased to exist, having been wiped out by genocidal warfare. Tanzanian chimps, like Hitler’s storm troopers, had fought for lebensraum.

My own fieldwork on chimps in Kibale Forest was spurred directly by these Gombe killings. In the 1970s, one primate killing another of the same species was the hottest issue in primatology. My mission? To find out whether these warlike killings were normal or an artifact of the researchers having provisioned the chimps with food to observe them. This was an important question, because if the chimps had killed only because humans had severely disrupted their normal lives, it would shed far less light on the natural origins and functions of warfare than if their killings were normal.

In Kibale I found that wild males (none of whom were ever fed anything by anyone) were very tightly allied with each other. They traveled together and preferred one another as companions over females in virtually all activities except mating. But I saw no lethal clashes between the males of the Ngogo community (my primary, and larger, study community) and the Kanyawara community (my secondary com­munity) ten miles north. Indeed, I never witnessed any male from one community meet or be near any male known to be of the other community. In short, I saw no occasion for border clashes. But the solidarity with which males from both communities “cemented” themselves to their buddies convinced me that they were tight for a reason. So, with a boldness that I knew would receive the scorn of some social scientists, in my book East of the Mountains of the Moon I predicted that the male chimps I observed in Uganda were naturally organized socially, as were those in Gombe and Mahale, and that this male solidarity was a specific adaptation to survive (at least) or win (at best) in intercommunity relations shaped primarily by war. I went out on a limb and said that Kibale male chimps were warlike—as warlike as any chimps anywhere.

After my fieldwork ended in 1981, years passed before my conclusion was proven accurate. In 1988, 1992, and 1994, an adult male of the Kanyawara community, then under study by Dr. Gilbert Isabirye Basuta, was killed, apparently by males of the Wantabu community. I had only suspected the existence of the Wantabu community, located between Kanyawara and Ngogo. The Wantabu chimps range immediately south of Kanyawara and north of Ngogo, where I had spent most of my time. Significantly, all three Kanyawara males were killed in combat, all three died in the same border region between the two communities’ territories, and at least two died within hours of prolonged territorial pant-hooting and displaying by males of both communities along this border.

No reasonable doubt exists today that the natural strategy of common chimpanzees is to establish, maintain, defend, or expand a kin group territory via lethal warfare. Clearly their aggressive expansion is most likely when one community outnumbers a neighboring one. Between equal-size groups, active (as opposed to latent) war seems very rare, if not nonexistent.

Annihilation on the scale observed in Gombe and Mahale may seem extreme outside human war. A stunning 30 percent of Gombe’s adult males died at the hands of other chimps. But these killer apes simply acted out the logic of reproductive advantage. They gained more of the two resources that limited their reproduction most: females and the territory needed to raise more offspring. Unlike their hyperaggressive but noncooperative cousins, the gorillas and orangutans, these chimps won in warfare via extreme cooperation and solidarity among kin-related males. (The endangered pygmy chimps, or bonobos, register lower on the violence curve than chimps, but veteran Japanese researchers have witnessed several “severe” fights between adult males of opposing communities. Thus the wishful claim that the “peaceful” bonobo should give us hope is likely premature, as it was with chimps until 1974.) In addition, male chimp solidarity was not merely a martial fervor that erupted briefly into lethal aggression and then abated. Instead, it was a permanent state, evident further as males shared each other’s females.

What is the significance of chimp war? It is important in what it shows us about cooperative violence, which usually erupts only as enlightened self-interest. Group aggression confers such a huge winning edge against single competitors that, once it entered the arms race of sexual selection, kin selection instantly forged it into the most seri­ous weapon in any male’s behavioral arsenal. No male on his own could ever compete and win against a martial system like that of wild chimpanzees.

Eerie parallels also exist between warfare by juvenile street gangs and warfare by chimps. First, gang homicide, though driven by the illegal drug trade (instead of by fruit trees and females), is far more often related to control and defense of territory than to drugs. Second, street gang death tolls are horrific. In the 1990s, U.S. juvenile gang killings have averaged 1,000 per year, and these killings are often the result of tit-for-tat retaliation. Third, as violent as gang members are, they commit few rapes. Instead, enough women are attracted to gang members to satisfy them. Fourth, homicides in individual gangs cycle in bursts and lulls that varied 660 percent in annual death tolls. Like chimp wars, gang wars run hot and cold.

It should be noted that male chimps from Mahale and Gombe (and likely Kibale as well) waged war on a neighboring community only when it, the “enemy,” was a lot smaller and weaker than their own community, containing half or fewer adult males. It is no overstatement to say that chimps are Machiavellian—or, to put it another way, politically devious and violent men are chimpanzee-like!

These studies of wild chimps tell us that solidarity in aggression among a community’s male kin is their standard strategy to reproduce and that this strategy has been around for a long time. How do we know? Despite their fierce and violent competition, male chimps are only 123 percent the weight of females, evidence that winning against other males no longer hinges on the more primitive orangutan or gorilla strategy of being a huge and formidable individual. Instead, winning depends on group size of male kin who cooperate as an army. Were this a recent evolutionary development, male chimps would be both big and cooperative.

Although chimps teach us what the law of the jungle really means, they also teach us what being social is all about. Sociability is for individual advantage. Within the chimps’ fusion-fission society, each ape’s decisions as to whether to socialize and with whom are based solely on how to best enhance his or her own reproductive success. Thus chimpanzee social structure—violent and otherwise—owes its form ultimately to each individual’s reproductive strategies and, by extension, to each one’s individual decisions. Warfare is simply the social version of combat.

Chimp social structure would be unique were it not for humans acting similarly. This is no coincidence. By most taxonomic criteria, chimps and humans are sibling species. Overall, chimp society is not only extremely sexist—with all adult males dominant over females—but also xenophobic to the extent of killing all alien males, many infants, and some old females who enter their territory. To some readers, my use of the word war may seem too strong to describe what male kin groups do. But systematic, protracted, deliberate, and cooperative brutal killings of every male in a neighboring community, plus genocidal and frequent cannibalistic murder of many of their offspring, followed by usurpation of the males’ mates and annexation of part or all of the losers’ territory, matches or exceeds the worst that humans do when they wage war.

Wild chimps reveal the natural contexts of territoriality, war, male cooperation, solidarity and sharing, nepotism, sexism, xenophobia, infanticide, murder, cannibalism, polygyny, and mating competition between kin groups of males—behaviors that have evolved through sexual selection. Also significant is the fact that none of these apes learned these violent behaviors by watching TV or by being victims of socioeconomic handicaps—poor schools, broken homes, bad fathers, illegal drugs, easy weapons, or any other sociological condition. Nor were these apes spurred to war by any political, religious, or economic ideology or by the rhetoric of an insane demagogue. They also were not seeking an “identity” or buckling under peer pressure. Instead, they were obeying instincts, coded in the male psyche, dictating that they must win against other males.

Nuclear physicist Freeman Dyson warns, “If we are to avoid destruction, we must first of all understand the human and historical context out of which destruction arises. We must understand what it is in human nature that makes war so damnably attractive.”

The great apes, especially chimpanzees, are the best living mirrors of primeval humankind It is up to us to look into that mirror (before we have destroyed all their tropical forests and killed them all) and identify what it is in the human male psyche that makes violence so “damnably attractive.” Now that we have seen the Machiavellian nature of martial chimpanzees, it is time to revisit Homo sapiens.

Are Human Warriors Natural-Born Killers?

IN ALL WARS ever fought by men, some men have killed, while others have avoided doing so. This inconsistency has spurred many idealists to deny that men are instinctive warriors. Instead, they insist, killing must be pounded into each of us against the grain. According to journalist Alessandra Stanley, “Yes, boys have a primitive urge to fight, an easily tapped aggression. But killing is not instinctive; it is an acquired taste, something that grownups must pass on.” Historian Gwynne Dyer likewise claims, ‘Aggression is certainly part of our genetic makeup, and necessarily so, but the normal human being’s quota of aggression will not even cause him to kill acquaintances, let alone wage war against strangers from a different country.”

Both are wrong. People’s “quotas of aggression” are all too often high enough to kill both acquaintances and strangers. During the Vietnam War, for example, Ho Chi Minh’s forces killed fifty-eight thousand Americans. But during the same time span, Americans murdered far more Americans at home—and most of those murdered were acquaintances (or even more intimate). According to political scientists Paul Seabury and Angelo Codevilla, “An ineluctable fact is that human intercourse all too naturally produces circumstances in which reasonable people regard kill or be killed as the best option available.”

This reality is so obvious to biologists that, despite his personal aversion to believing that men are innate killers, German ethologist Irenäus Eibl-Eibesfeldt found himself listing the universal traits of men the world over that are vital to war: loyalty to group members; readiness to react aggressively to outside threats; motivation to fight, dominate, and act territorially; universal fear of strangers; and intolerance of those who deviate from group norms.

[p. 165] "Chimp social structure would be unique were it not for humans acting similarly.  This is no coincidence.  By most taxonomic criteria, chimps and humans are sibling species.  Overall, chimp society is not only extremely sexist -- with all adult males dominant over females -- but also xenophobic to the extent of killing all alien males, many infants, and some old females who enter their territory.  To some readers, my use of the word war may seem too strong to describe what male kin groups do.  But systematic, protracted, deliberate, and cooperative brutal killings of every male in a neighboring community, plus genocidal and frequent cannibalistic murder of many of their offspring, followed by usurpation of the males' mates and annexation of part or all of the losers' territory, matches or exceeds the worst that humans do when they wage war.


"Wild chimps reveal the natural contexts of territoriality, war, male cooperation, solidarity and sharing, nepotism, sexism, xenophobia, infanticide, murder, cannibalism, polygyny, and mating competition between kin groups of males -- behaviors that have evolved through sexual selection.  Also significant is the fact that none of these apes learned these violent behaviors by watching TV or by being victims of socioeconomic handicaps -- poor schools, broken homes, bad fathers, illegal drugs, easy weapons, or any other sociological condition.  Nor were these apes spurred to war by any political, religious, or economic ideology or by the rhetoric of an insane demagogue.  They also were not seeking an 'identity' or buckling under peer pressure.  Instead, they were obeying instincts, coded in the male psyche, dictating that they must win against other males." [p. 176]


"The central 'truth' of sociologists is that nature, especially that of humankind, is nice and that people are designed to do things that, all in all, favor the survival of their species.  Hence people could never be equipped by nature with instincts to kill other people.  This idea comes from the Bambi school of biology, a Disneyesque vision of nature as a collection of moralistic and altruistic creatures.  It admires nature for its harmony and beauty of form and for its apparent 'balance' or even cooperativeness.  It admires the deer for its beauty and fleetness, and it grudgingly admires the lion for its power and nobility of form.  If anything is really wrong with us, it explains, it is a sociocultural problem that we can fix by resocializing people.  It is not a biological problem.


"Nature, however, is actually a dynamic state of recurring strife of relentless competition, dedicated predators and parasites, and selfish defense.  The deer owes its beauty and fleetness to predators such as mountain lions, which kill the clumsiest and slowest deer first; to competitors for food; and to competition between males to mate.  Without predators, deer would not only lack fleetness; they would lack legs altogether.  They would be slugs oozing from one plant to another.  Yet even if these deer-slugs were the only animals out there, natural selection would favor the evolution of faster and more aggressive deer-slugs and would favor any other trait that made them superior competitors against each other.  This would include the killing of one deer-slug by another in situations where it boiled down to kill or die.


"Moreover, the power and noble visage of the lion (or of the family cat or dog, for that matter) rest entirely on natural selection having shaped not only a fleet predator and efficient killing machine but also a very violent competitor against its own kind in situations where the options were narrowed to exclude or kill, or else kill to survive or reproduce." [p. 179]