A report in Nature on 10,000-year-old skeletons unearthed in West Turkana, Kenya is being touted as evidence for the assertion that war has deep evolutionary roots. According to this claim, the tendency for lethal group fighting dates back millions of years to the common ancestor of humans and chimpanzees, who have been observed engaging in deadly raids.
The Nature report does not bolster the case for what I call the deep-roots theory of war. Far from it. But it does reveal how eager some scientists and journalists are to accept the theory in spite of a lack of evidence.
The report describes a site containing the remains of 27 individuals — including a pregnant woman and six children — who were apparently massacred near a lagoon. 10 of the skeletons show clear-cut signs of violence, including crushed skulls and broken limbs and embedded obsidian spear points.
Anthropologist Luke Glowacki told Bret Stetka of Scientific American that the West Turkana massacre “suggests a continuum between chimpanzee raiding and full-blown human warfare.” The Atlantic, Telegraph, Guardian and other publications also proposed that the massacre reveals war’s deep evolutionary roots. Here are problems with that interpretation:
*The deep-roots theory holds that lethal group conflict evolved not ten thousand or tens of thousands or hundreds of thousands but millions of years ago. Critics of the theory have long accepted that some humans, including hunter-gatherers, engaged in group violence 10,000 years ago and even earlier. The oldest clear-cut relic of group violence is a 13,000-year-old grave in the Jebel Sahaba region of Sudan. The grave contains 59 skeletons, 24 of which bear marks of violence, such as embedded projectile points.
- Other than the Jebel Sahaba site, evidence of war or even homicide dating back more than 10,000 years is extremely rare. In 2013 anthropologists Jonathan Haas and Matthew Piscitelli carried out an exhaustive review of hominid remains more than 10,000 years old, including more than 2,900 skeletons from over 400 different sites. Excluding the Jebel Sahaba skeletons, Haas and Piscitelli found only four skeletons bearing signs of violence.
- The West Turkana massacre victims might not have been nomadic hunter-gatherers, as our ancestors were throughout most of the Paleolithic era (which began just over two millions years ago and lasted until the dawn of agriculture). Instead, the victims might have been making the transition to a more settled mode of existence, as were other societies in northern Africa, Mesopotamia and elsewhere. According to the Nature authors, 10,000 years ago West Turkana was “a fertile lakeshore landscape sustaining a substantial population of hunter-gatherers; the presence of pottery may be indicative of some storage and so reduced mobility.”
- A 2013 study by anthropologists Douglas Fry and Patrik Soderberg found scant evidence of warfare among 21 modern-day hunter-gatherer societies on five continents. Three of the societies had no observed killings of any kind, and 10 had no killings carried out by more than one perpetrator. Their findings, Fry and Soderberg concluded, “contradict recent assertions that [mobile foragers] regularly engage in coalitionist war against other groups.”
The debate over the deep-roots theory matters. As a New York Times editorial on the Kenyan dig points out, President Barack Obama seems to favor the notion that war has “deep biological roots.” During his 2009 Nobel Prize speech, Obama stated that war “appeared with the first man” and that “we will not eradicate violent conflict in our lifetimes.” This sort of fatalism could undermine efforts to achieve permanent peace.
The evidence is overwhelming that war, far from being an innate behavior that evolved millions of years ago, was a cultural innovation — an “invention,” as Margaret Mead put it — that emerged relatively recently in our prehistory, toward the end of the Paleolithic era. We should take responsibility for our wars instead of blaming them on our genes.
John Horgan directs the Center for Science Writings, which is part of the Stevens College of Arts & Letters. This column is adapted from one originally published on his Scientific American blog, “Cross-check.”
