If some of our nearest evolutionary relatives, such as mountain gorillas, exhibit a home-range-based system of sociospatial behavior, then why did humans evolve a system of territorial functioning instead? Stated differently, what was the value of a system based on territorial functioning in our environment of evolutionary adaptedness, several million years ago on the savannas and in the forests of East Africa? This chapter sketches an answer to this question, drawing on recent anthropological theorizing. A territory-based spatial organization, coupled with a particular group/family structure, probably had significant adaptive value for primitive hominids.

The importance of territorial functioning in protohominid emergence

Anthropologists have long wondered what physical, cultural, and behavioral changes allowed the protohominids, emerging before Homo erectus and Homo sapiens, to flourish and compete successfully with pongids (gorillas, chimps, orangutans). Current evidence suggests that bipedality, the emergence of material culture involving toolmaking, and the expansion of the neocortex and the concomitant larger braincase, although applicable to later species, did not spur the emergence of early protohominids.

When protohominids emerged during the Miocene epoch (which began about 25 million years ago and ended roughly 7 million years ago), they lived not only in high savannas or grasslands but also in canopy forest and woodlands, and all these settings were characterized by marked seasonally. A selective advantage would have accrued to protohominids if they engaged in a pattern of behavior that allowed decreased infant mortality from environmental hazards in these varied settings.