Forager Habitat Quality: Quantifying Hunter-Gatherer Habitats, Past and Present

Abstract

Prior to the advent of agriculture approximately 10,000 years ago, hunting and gathering were the sole means of subsistence for our species. Contemporary populations of part-time foragers, who practicing mixed subsistence strategies that incorporate wild foods, offer powerful models for understanding the behaviors and pressures that shaped the evolution of our species. This dissertation seeks to understand various factors that contribute to the foraging and demographic success of ethnographic (past) and contemporary foragers within different habitat types. Chapter 2 tests the common conception that contemporary foragers tend to occupy marginal habitats, and that their utility for informing the socioecology of ancient humans may thereby be diminished. It uses a broad ethnographic sample, combined with data on net primary productivity, to make a thorough assessment of the relationship between habitat quality and population density for pre-industrial societies. Results show that habitats occupied by recent foragers have not tended to be marginal. Wetland and deltaic area have been hypothesized to be productive habitats for human populations. Chapter 3 provides a test of foraging returns in a wet savanna habitat, the Okavango Delta. Women foraged in adjacent wet and dry habitats while observed during focal follows. Post-encounter return rates were paired with detailed analyses of nutritional content and women’s energetic expenditure, evaluating the profitability of each habitat. Contrary to expectation, energy returns were generally higher in dry than wet habitats. Underground storage organs (USOs) are an important component of the plant diet for humans in a wide array of habitat types, and starch is the dominant form of energy stored in USOs. Chapter 4 analyzes the starch content of USOs across several African habitat types relevant to human evolution. The data reveal wide variability in starch content within and among habitats. Rainforest habitats bore surprisingly starchy USO tissues that rivaled those of domesticated species. Overall, this thesis contributes to our understanding of how foragers would have utilized plant resources across a range of paleoenvironments.