Between 1974 and 1978, a tribal war raged in Tanzania. After the death of a local leader, two rival factions were formed which engaged in classic guerrilla warfare. In the end, the northern group systematically eliminated the southern group, killing nearly all of them--even the children--and kidnapping the survivors.

But the unique factor in this war was that all of the participants were Chimpanzees.

Chimp using a twig to poke food from a tree trunk

Until the 1960's, there had been little effort to study the great apes in the wild. That changed when Dr Louis Leakey, a prominent paleontologist in Africa, decided that one way to learn more about the possible social structures of early humans ancestors was to study our closest living relatives. So he assigned three students to the task: one was sent to Borneo to study Orang-utans, another was sent to Rwanda to study Gorillas, and a third, Jane Goodall, was sent to Gombe Forest in Tanzania to study Chimpanzees.

It became one of the most remarkable longterm scientific studies ever undertaken. Over the next five decades, Jane Goodall uncovered much about Chimpanzees that had not been known before. The Chimps, our closest genetic relatives, were uncannily like humans: they formed tightly-knit social groups and complex political structures that were based on alliances and partnerships. They had a thorough knowledge of their natural surroundings and were able to utilize them intelligently--they were even able to select plants with medicinal properties when they needed them. The chimps were able to make and use tools (an area formerly thought to be exclusively human), including stone hammers for nut-cracking, stripped twigs for "termite fishing", and sharpened wooden spears for hunting bushbabies--and these formed local "cultures", with each troop passing its own knowledge base from generation to generation. Once thought to be strictly vegetarian, the Chimps were discovered to form organized hunting parties that would carefully stalk and kill Colobus Monkeys as food, sharing the highly-prized meat among the members of the hunting party. Much of what we know today about Chimpanzees in the wild comes from Jane Goodall and her work.

But Goodall also faced some criticism. She (and others) came to view the Chimps as hairy little people, a sort of hippie band that lived peacefully in harmony with Mother Nature--in contrast to the destructive and warlike humans. There were accusations that she was allowing emotional involvement with her study subjects to cloud and influence her scientific judgement.

The disillusionment came in 1974.

Three years earlier, the alpha male leader of one of the troops at Gombe, who Goodall had named Leakey, died. Although she did not recognize it at the time, her detailed field notes would later show that this produced a split in the Chimp band that would later be fatal for many of them.

Chimpanzee troops are based on a hierarchical political structure. At the top is the alpha male. He not only gets to mate with all the females in the troop, but he functions as the "tribal leader"--he makes all the decisions about where the troop will move, when it is time to feed or sleep, and how to react to neighboring troops. But the alpha male cannot rule alone: his position depends on a complex web of alliances and partnerships with other males of the group. The result is a Byzantine-like political landscape in which factions are formed (and broken), the strongest alliance gets to rule, and the other alliances make their schemes and bide their time until they get a chance to seize power for themselves.

As the alpha leader, Leakey had been strong, well-supported by an alliance of lieutenants, and had been able to keep order in the troop, which consisted of about 15 males and 15 females. But upon his death in 1971, the leadership fell to Humphrey, a large adult male. Humphrey did not have the extensive network of support that Leakey had, and within a short time his leadership was challenged by a pair of younger brothers named Charlie and Hugh. Over a period of years, the rest of the band chose up sides. The Charlie/Hugh "insurgent" faction began spending less and less time with the others--they tended to groom each other and ignore the Humphrey faction, and vice versa. Eventually the split became physical as well as social: the Charlie/Hugh faction moved into a patch of territory to the south and became known as the Kahama troop, while the Humphrey faction remained in the north and was labelled the Kasakela troop. Goodall presumed that the split would result in two permanent new troops, the Kahama group with 7 adult males and 3 females, and the larger Kasakela group with 8 males and 12 females.

Instead, what happened next was extraordinary.

As Goodall and her field observers watched and recorded detailed notes, the Kasakela troop began what could only be described as a systematic campaign of violence against the Kahamas. Groups of males from the Kasakela began stealthily making their way into Kahama territory, apparently searching for something. In January 1974 it became apparent what they were looking for: a band of six Kasakela males surrounded a young Kahama male named Godi, who was eating fruits in a tree, alone. The Kasakelas pulled him from the tree and dragged him to the ground, and, while several of the males held Godi to the ground by the arms and legs, the others beat and bit him, pummeling him several times with a large rock. Godi crawled away and was never seen again--presumably he died from the beating.

The Kasakelas seemed to be using a deliberate tactic which took advantage of Chimpanzee ecology. Although Chimps are highly social animals, one thing they do not normally do is share food. When it comes to foraging, each adult is on his or her own. And since a large group of Chimps would quickly denude any given area of its edible resources, the usual pattern is that each individual Chimp will disperse from the others in the morning to forage in the surrounding forest, returning to the group later in the afternoon. The Kasakela males seemed to be intentionally entering Kahama territory in force and looking for lone individuals separated from their troop during feeding time, which were vulnerable to attack. It was classic guerrilla warfare.

Using these tactics, the Kasakelas, over the next four years, systematically sought out and ambushed the Kahama males, one at a time. In a ghoulish sideline, one of the Kahama females, named Passion, began to kidnap, kill and eat the infants in her own troop, perhaps because of the unending stress. In 1977, the Kahama males Charlie and Sniff were killed: they were the last males left. Once the troop's males were all gone, the Kasakela raiders turned to the females. Three of these were forcibly dragged back to Kasakela territory, another was observed being beaten and bitten to death, and the rest disappeared and were presumably also killed. All of their infants were also destroyed. By 1978, the Kahama troop no longer existed. It had been totally and systematically wiped out.

For Goodall, the disillusionment was devastating. She later wrote: "For several years I struggled to come to terms with this new knowledge. Often when I woke in the night, horrific pictures sprang unbidden to my mind." One image that particularly affected her was that of a young male named, ironically, Satan, cupping his hands to catch the blood flowing from a dying Kahama male's face, so he could drink it.

The Kasakela troop, victorious in its four-year war, now moved into the empty Kahama territory. But their victory was short-lived. Border disputes soon broke out between the Kasakelas and their new neighbors, the much-larger Kalande troop. The Kasakelas did not have the numbers to win that dispute, and they retreated back to their former territory to avoid conflict.

The Gombe Chimpanzee War both electrified and divided the scientific community. For some, it was observed proof that inter-tribal violence and warfare in primates is genetic, an unalterable part of our early ancestors and our closest relatives, as well as ourselves. For others, the Gombe War was just an aberration: some argued that it was provoked by the presence of Goodall herself (in her initial studies, she had been providing food to some of the troops to entice them into view so the researchers could watch them), others argued that it was caused by a temporary overcrowding and lack of resources.

The issue prompted further study: researchers found other instances of inter-troop Chimpanzee violence, both in troops that had experienced provisioning and in those who had not, and in some cases the troops were being observed by non-intrusive methods. It was found that over half of the Chimpanzees known to have been killed by other Chimps came from just two conflicts, including the Gombe War, and in both of these a lack of resources may have been a motivating factor. In addition, "warfare" was also found in other primate species, most notably in Spider Monkeys in Mexico in 2002--this conflict seems to have been motivated by the lack of available adult females in one of the troops.

And where did the Bonobos fit into all this...? The Bonobo is a separate species of Chimpanzee that split away from the common Chimp about a million years ago (long after human ancestors did). Studies seem to show that they are much closer to Goodall's vision of the peaceful nature child than the Chimpanzee is: Bonobo troops are run by dominant females, not males, and they take "make love, not war" to an art form. Sex (with both males and females) is used not only as a social glue to bond the members of the troop together, but also as a way of easing tensions with neighboring troops and avoiding conflicts. Because the Bonobo habitat is ecologically richer than that of the Chimpanzees, it may be that their benevolent lifestyle is made possible by this abundance of local resources--when there is plenty for all, there is no need to fight over who gets what.

NOTE: As some of you already know, all of my diaries here are draft chapters for a number of books I am working on. So I welcome any corrections you may have, whether it's typos or places that are unclear or factual errors. I think of y'all as my pre-publication editors and proofreaders. ;)