1Department of Human Evolutionary Biology, Harvard University, Cambridge, USA, 2Departments of Anthropology and Biological Sciences, Dartmouth College, Hanover, USA
Saturday All day, Plaza Level
One of the most enduring concepts in anthropology is the perception that farming incurs greater energetic costs than hunting and gathering. Much of this concept stems from the seminal work of Lee and the subjective impressions of Dobe-area !Kung living in the 1960s. Although the !Kung had little direct experience with farming, there have been few quantitative attempts to verify their views. As a result, the comparative energetics of human subsistence activities are virtually unknown. Here we report on a population, the Twa of southwestern Uganda, that was forced to shift from hunting and gathering to subsistence farming in 1991. We measured the energetics of women resting, standing, foraging (on- and off-trail), and digging for wild yams (Dioscorea spp.) in Bwindi Impenetrable National Park. Repeated measures were also performed for a laborious agricultural task – hoeing – that was also associated with underground tubers. We found that the cost of hoeing, measured by VO2 kg-1 min-1, was significantly higher than all aspects of foraging in the forest, including digging.
A contributing factor to this result might be the short stature (pygmy phenotype) of the Twa. A relatively lower surface area to volume ratio is expected to constrain the benefits of evaporative cooling under warmer temperatures. Thus the high energetic costs of farming – both real and perceived – might be due in large part to the small stature of human hunter-gatherers. We suggest that a size-related ability to mitigate thermal and energetic costs might have been a key factor in the origins of farming.
This study was funded by Harvard University and the David and Lucille Packard Foundation.