By Sarah Peacey
Is warfare encoded in our genes, or did it appear as a result of the pressures of civilisation? Could a willingness to fight neighbouring groups have provided our ancestors with an evolutionary advantage? With conflicts raging across the globe, these questions have implications for understanding our past, and perhaps our future as well.
The Enlightenment philosophers Hobbes and Rousseau had different visions of prehistory. Hobbes saw humanity’s earliest days as dominated by fear and warfare, whereas Rousseau thought that, without the influence of civilisation, humans would be at peace, in harmony with nature.
The debate continues to this day. Without a time machine, researchers examining warfare in prehistory largely rely on archaeology, primatology and anthropology.
Earlier this year, one of the most striking examples of prehistoric intergroup violence was published – 27 skeletons, including those of children, were found at Nataruk near Lake Turkana, Kenya. Blades embedded in bones, fractured skulls and other injuries demonstrated this had been a massacre1. The bodies were left, unburied, next to a lagoon on the lake’s former western shore, around 10,000 years ago.
The Nataruk finds are being publicized as the earliest evidence for prehistoric violence in hunter gatherers. A 12,000-14,000 year-old cemetery at Jebel Sahaba, in Sudan, was previously thought to be the first, but its date is less certain, and some have claimed that since the bodies were buried in a cemetery, they were linked to a settlement, and not hunter gatherers.
The evidence for warfare becomes clearer in the archaeological record after the beginning of the agricultural revolution (approximately 10,000 years ago), when humanity moved from hunting and gathering to farming settlements. War may have existed before then, but there are so few remains from the early days of Homo sapiens, and causes of death can be extremely difficult to ascertain from skeletons. This means that at the moment, the archaeology remains inconclusive.
Animal behaviour studies provide another means of exploring the debate.
Jane Goodall’s discovery that chimpanzees make war shocked the world. A group of chimpanzees (Pan troglodytes) in Tanzania were observed beating members of a rival community to death, one by one, before taking over the defeated group’s territory2. This behaviour in such a closely-related species, had implications for our understanding of human character. Despite attempts to dispute Goodall’s findings, similar patterns of behaviour were later discovered in other groups, and evidence for warfare in one of our closest relatives became indisputable.
However, bonobos (Pan paniscus), also known as pygmy chimpanzees, share as much DNA with us as chimps do, but are overall more peaceful, despite some anecdotal reports of aggression between groups. This is partly attributed to differences in the two species’ social systems. For example, bonobos’ societies are female-dominated, which perhaps keeps male aggression in check, whereas chimpanzees’ social hierarchy is male-dominated.3
How did our last common ancestor behave? Were they like bellicose chimpanzees or peaceful bonobos? Although parallels between all three species are fascinating, using them to answer this question is difficult, as ultimately each species followed its own evolutionary pathway.
But chimpanzees demonstrate that war without civilisation exists, in a species similar to our own. Not only that, but similarities can be seen between chimpanzee and human hunter-gatherer warfare. For example, in both species, an imbalance of power, and risk-averse tactics are often a feature of attacks: a group of chimpanzees will assault a lone rival, and hunter-gatherer groups favour guerrilla warfare and surprise tactics to pitched battles.
Anthropologists, whose knowledge of ‘traditional’ societies could provide clues as to how our ancestors behaved, also took sides in the Hobbes-Rousseau debate. Margaret Mead’s research on Samoan islanders led her to conclude that ‘Warfare is only an invention,’ which had not existed before civilisation, while Napoleon Chagnon reported that among the Venezuelan Yanomamö, fighting and raids on enemy villages were commonplace. Both were criticised: Mead for overlooking widespread evidence of violence in Samoa4, and Chagnon for inappropriately using a society of horticulturalists as a proxy for prehistoric hunter-gatherers5.
Of course, any traditional society anthropologists choose to study has still been exposed to outside influences. And they differ vastly from one another, not least in their participation in warfare. But early accounts suggest that lethal aggression did exist between some hunter-gatherer groups before their contact with other societies. Waldemar Jochelson, who studied the Siberian Yukaghir in the 1890s, described them as having persecuted their enemies like ‘wild beasts’6. Similarly, the Andaman Islanders had longstanding feuds between themselves, and participated in dawn raids on enemy camps.
So, it is difficult to conclude that prehistory was free from intergroup aggression. Azar Gat and Stephen Pinker, amongst others, argue that warfare existed before the agricultural revolution7,8. Pinker also claims that violence has overall decreased over the centuries. This may seem difficult to believe at the beginning of 2016. But his argument carries sufficient conviction to offer at least the suggestion of hope for the future.
1. Lahr et al (2016) Inter-group violence among early Holocene hunter-gatherers of West Turkana, Kenya Nature 529, 394–398 (21 January 2016) DOI: 10.1038/nature16477
2. Goodall, Jane (1986) The Chimpanzees of Gombe: Patterns of Behaviour Cambridge, Massachusetts: Harvard University Press
3. Wrangham, Richard & Peterson, Dale (1996) Demonic Males: Apes and the Origins of Human Violence Boston: Houghton Mifflin
4. Freeman, Derek (1983) Margaret Mead and Samoa: The Making and Unmaking of an Anthropological Myth Cambridge Massachusetts: Harvard University Press
5. Fry, Douglas (2007) Beyond War: the Human Potential for Peace Oxford: Oxford University Press
6. Jochelson, Waldemar (1926) The Yukaghir and the Yukaghirized Tungus, Memoir of the American Museum of Natural History Volume IX, New York: G.E. Stechert, American Agents, Leiden: E.J. Brill Ltd, Printers and Publishers
7. Gat, Azar (2006) War in human civilisation Oxford: Oxford University Press
8. Pinker, Steven (2011) The Better Angels of Our Nature: A History of Violence and Humanity London: Penguin Books
Keeley, Lawrence (1997) War Before Civilisation: the Myth of the Peaceful Savage New York: Oxford University Press
de Waal, Frans (1997) Bonobo: The Forgotten Ape Berkeley: University of California Press