Productivity loss associated with physical impairment in a contemporary small-scale subsistence population

Abstract

AbstractHumans experience unique physical impairments with potentially severe economic consequences. Quantifying the burden of impairment in subsistence populations is critical for understanding selection pressures underlying strategies that minimize risk of production deficits. We examine among forager-horticulturalists whether compromised bone strength (indicated by vertebral fracture and lower bone mineral density, BMD) is associated with diminished subsistence involvement. We estimate the magnitude of productivity losses associated with compromised bone strength. Fracture is associated with cessation of hunting, tree chopping and walking long distances, but not tool manufacture. Age-specific productivity losses from hunting cessation related to fracture and lower BMD are substantial: ∼397 lost kcals/day, with expected future losses of up to 1.88 million kcals (22% of expected production). Productivity loss is thus substantial for high strength and endurance tasks. Determining the extent to which impairment obstructs productivity in contemporary subsistence populations improves the ability to infer consequences of impairment over human evolution.