Abstract
Birth seasonality is a phenomenon whereby populations can be
characterized by a single month or season in which births peak. While
non-human animal research suggests seasonal birth-pulses are related to
variation in climate and local energy availability, social scientists
debate the mechanisms responsible for it in humans. Here we investigate
the role of precipitation, temperature, and energy availability on
seasonal birth pulses using a historical dataset from the Baja
California peninsula - a hot, arid desert that experiences seasonal
fluctuations in temperature, precipitation, and energy associated with
the North American Monsoonal. Analyses suggest that local energy
availability (as measured through NDVI) predicts seasonal birth pulses,
while temperature and precipitation do not; however, both are indirectly
related to it through their direct effects on NDVI. Our analyses
demonstrate the importance of local energy availability on human
reproductive timing and suggest that human birth seasonality is a form
of traditional ecological knowledge.