In this lecture, Dr. Alison Brooks reviews the early archaeological evidence of widespread human interactions and the formation of tribes. In Africa, the birthplace of our species, the evidence is particularly ancient. Dr. Brooks discusses what this evidence can tell us about the evolution of tribalism and, more broadly, of our species, and how it points to the earliest history of ethnic divisions and intergroup violence. This talk was part of a Leakey Foundation symposium entitled, "Our Tribal Nature: Tribalism, Politics, and Evolution." The symposium was held in September 2019 at the Morgan Library in New York. About the speaker: Dr. Alison Brooks is a professor in the Department of Anthropology at the George Washington University. A paleoanthropologist and archaeologist interested in the origins of our species, Dr. Brooks has conducted research in France, the Near East, China, and multiple African countries to document the emergence of our characteristic behaviors, including symbolic behavior, long-distance social contacts, technological innovation, complex economic strategies, and “living in our heads” with reference to an ‘imagined community,’ tribe or nation. She argues that our behavioral capabilities appeared first in Africa and that these capabilities emerged gradually, not in a sudden “mutation event.” Recently, Brooks has focused on the development and consequences of large-scale social networks in the earliest days of our species.