Some 25 years into her long observation of chimpanzees in Tanzania’s Gombe Stream National Park, primatologist Jane Goodall witnessed a unique and unsettling event: a permanent splinter of the once-peaceful chimpanzee community into two rival groups, followed by four bloody years of chimp-on-chimp violence.
The cause of the so-called Gombe War has long been debated. Some scientists attribute the schism to humans, charging that a change in the banana supply at the feeding station researchers used to lure chimps to the area precipitated the conflict. But a recent study of the copious notes Goodall and her team kept from the time points instead to a battle for status and power that might look uncomfortably familiar to humans.
In the years preceding the split, researchers noted what appeared to be tense and avoidant behavior between a male chimpanzee they named Humphrey—the group’s alpha, or most dominant male—and two rivals named Charlie and Hugh, the second- and third-highest ranking males.
“Humphrey was large and he was known to throw rocks, which was scary,” wrote Duke University professor Anne Pusey, a co-author of the study who witnessed the conflict in the Gombe as a doctoral student in the 1970s. “He was able to intimidate Charlie and Hugh separately, but when they were together he tended to keep out of the way.”
At the same time, reproductive patterns had resulted in an unusually high male-to-female sex ratio of five males to one female. This left the Gombe community with too many male chimps competing for too few female mates.
Primates compete for the thing that most affects their ability to mate and reproduce, said Joseph T. Feldblum, a postdoctoral associate at Duke University and the study’s lead author. For females, that’s typically food. For males, it’s typically females.
And the most important thing that gives males a competitive edge in reproduction is status.
Being the dominant male isn’t just an ego boost for apes. It is a male individual’s best chance at reproduction and the survival of his genes.
“Basically dominance rank influences access to the resources that allow individuals to better survive and reproduce,” Feldblum said.
The pre-existing competition between between alpha Humphrey and his rivals Charlie and Hugh was intensified by the scarcity of the females they competed for. And just like in human conflicts, members of the community took sides in the escalating tensions, resulting in a series of violent intergroup attacks that killed as many as 14 chimpanzees.
Why should humans care about the causes of a chimpanzee war that happened more than 40 years ago? As the researchers point out, political conflict and competition for scarce resources are also the two primary factors in falling-outs within human groups.
Humphrey, Charlie, and Hugh’s inability to co-exist peacefully led to tragic consequences for the rest of their community, but it was also probably extremely hard on those three chimps themselves. Research on great apes has shown that dominance and stress levels are closely linked.
As Stanford University biology professor Robert Sapolsky has found, the lower a male baboon’s position in his social hierarchy, the greater his stress level—except during times of transition, when high-ranking males’ stress level spikes as they fight to maintain their dominance.
Another similarity between chimps and humans: When high-status individuals fight, nobody wins.