Some researchers argue that human warfare develops out of innate tendencies for collective violence and that only culture, or reason, keeps violent and aggressive urges in check. But the story is not so simple. The evolution of human culture not only led to ways of instituting peace, it also brought about a means for organizing and structuring violence. Culture was key, for example, to the emergence of war.
Researchers don’t know exactly when warfare first began, but some of the earliest evidence comes from about 10,000–13,000 years ago. For instance, at a 10,000-year-old site in Kenya called Nataruk, scientists excavated a group of people who all showed signs of violent death. One person’s cranium even had an obsidian blade embedded in it. And at Jebel Sahaba, a site located along the Nile River in Sudan that is estimated to be 13,000 years old, archaeologists uncovered a cemetery that contained approximately 60 people, many of whom suffered traumatic death. These examples may seem ancient, but they aren’t that old compared to the entire history of the genus Homo, which evolved as early as 2.8 million years ago.
Based on the preponderance of archaeological, primatological, ethnographic, and genetic data, we believe that warfare emerged gradually over time and evolved in concert with complex cognition. These cognitive abilities allowed humans to think well beyond the immediate moment—to communicate in new ways and to plan for future action.
Such complex cognition began about 300,000 years ago, as evidenced by early Homo sapiens making markings, drawing designs and symbols. Other hints in the archaeological record of sophisticated thinking at early H. sapiens sites in Africa and across Eurasia include the use of personal adornments, such as beads and necklaces, as well as the fashioning of complex tools. All of these examples point to a long journey to becoming human. These remnant materials suggest an ability to think symbolically and creatively, to convey and assign identity, and to signal and receive such forms of communication.
Complex cognition meant that eventually humans could produce more food, build temples, engage in writing, and trade ideas across great distances. It also allowed for the emergence of organized violence on a larger scale. In our opinion, a combination of symbolic thinking and complex communication allowed people to cooperate in unprecedentedly sophisticated ways, which in turn opened the door for novel forms of organized violence. Human culture, then, provided a way for humans to wage war and justify it. (Other species, as far as we can tell, do not fight over ideas, concepts, and beliefs.)
People sometimes think of cooperation and aggression as opposite sides of the same coin, but they aren’t. It takes a lot of cooperation to launch, and win, a war. It also takes quite a bit of cooperation to avoid or prevent war. For instance, sometimes communities choose to intermarry so as to mitigate past tensions between them, thus creating new ties and minimizing the chances that future disagreements will lead to warfare.
Two interesting things to investigate are how human cognition developed and how those traits drove the development of both collective violence and peacemaking. An anthropological approach is thus key because we need to recognize how both our biology and culture are linked to the story of warfare. Ultimately, understanding the cultural motivations for war can also tell us how we can work toward building peace.