After digitalizing all of Goodall’s original field notes from her time at Gombe and then sifting through them, researchers built up an impressively detailed picture of the social interactions and friendships between the chimps at the time, and mapped how these changed. They published their results in the American Journal of Physical Anthropology.
They found that the seeds for the conflict were already there in the years leading up to the war. While at the end of the 1960s, all males were intermingling quite happily, by 1971, fractures were beginning to show. The northern and southern males were starting to spend less time with each other, and encounters became increasingly aggressive.
Within a year, the two sides had become distinct, with the chimpanzees staying and socializing only within their own groups, a full two years before the fighting spilled over into full-on warfare. The researchers suspect that the divide occurred after an ape called Humphrey became the alpha male, something the southern males Charlie and Hugh disagreed with.
Over the next four years, and a campaign of skirmishes, violence, and kidnapping, Humphrey and his northern community killed every single male in the southern group and took over their territory, as well as the only three surviving females. In fact, this latest study shows that it was likely the limited number of mature females in the forest at the time that precipitated the conflict.
The researchers suggest that – not unlike what we see in human communities today – the infighting among the males was largely driven by ambition, power, and jealousy, and as such would likely have occurred with or without Goodall being there.