Book excerpt: Humans have spent much of their history as hunter-gatherers. For this reason, understanding the nature of hunting and gathering societies and the underlying reasons for variation among contemporary groups has been a focus of anthropological research. Hunter-gatherer studies have been uneven in geographic scope, however, and much of what we know about hunter-gatherer socio-economic behavior comes from research conducted in high latitudes. Studies of hunter-gatherer complexity have also been limited, with much attention focused on historic groups and little on prehistoric complexity and/or variation.