Food storage, mobility, and the density-dependence of hunter-gatherer movement ecology

Mobility, food storage, and population density are central to the movement ecology of hunter -gatherer populations and understanding how these lifestyle traits covary over time and space has long been of interest to archaeologists and anthropologists. An important question that remains unresolved is the conditions under which hunter -gatherer populations reduce the cost of mobility by increasing sedentism. Here, we model the interaction of movement frequency, distance, food storage technology and population density in ethnographic data. We show that increasing levels of food storage technology reduces annual movement frequencies but has little impact on annual total mobility costs: mobility costs are more often related to population density than storage capacity. This is because while food storage effectively increases the window of time over which resources are available, storage in non -food -producing economies cannot increase the net productivity of landscapes. Therefore, populations who move less frequently have to move further each time they move because resources remain finite and so become depleted. We derive a mathematical model of hunter -gatherer movement ecology based on optimization principles and scaling theory and test its predictions using spatiallyexplicit linear mixed models. We show that the interaction of mobility, storage, and population density in data are remarkably consistent with theoretical predictions. Our results suggest that while food storage is a technological response to seasonal environments, mobility reduction is primarily a behavioral response to increasing population density.