As floodwaters continue to ravage Pakistan, photographers have documented the devastation in harrowing detail. As in most coverage of Third World disasters and the developing world, a number of images show people carrying heavy stuff on their heads with relative ease. Would we all be better off carrying bulky packages on our heads?
Only if we're ready to invest years of practice. With most load-bearing methods, the heavier the weight, the more energy you need to burn to carry it. Not so with head porterage. Based on studies of women of the Luo and Kikuyu tribes of East Africa, researchers have found that people can carry loads of up to 20 percent of their own body weight without expending any extra energy beyond what they'd use by walking around unencumbered. Above that figure, however, metabolic costs seem to increase proportionally with load weight. But don't start stacking groceries on your head just yet. The subjects in these studies began head-loading as children and had developed a peculiar gait that's one-third more efficient than the one we're likely to use.
For untrained controls who have not had years to strengthen the right muscles and build up spinal bone density, carrying things on your head actually requires more energy than using a backpack. And although the Luo and Kikuyu women did not have a significant incidence of musculoskeletal injuries, apart from permanently grooved skulls, other populations of head loaders have reported severe neck pain and generally prefer the stability and freedom of movement that back-loading affords. According to one study, many Xhosa women in South Africa employ head-loading because it happens to be well-suited to the rough, rural terrain and the particular objects they carry—like buckets of water and bundles of firewood. When they move to more urbanized areas, they ditch the practice. (The women also believed that head-loading was less socially acceptable in the city.) On the other hand, in Ghana, young females from the depressed rural north flock to big cities to labor as head porters, or kayayo, carrying absurdly large loads on their heads for as little as $2 a day.
Got a question about today's news? Ask the Explainer.
Explainer thanks Norman Heglund of the Université catholique de Louvain and Ray Lloyd of the University of Abertay Dundee.
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