One of the most startling sights on a first trip to Africa is a common one: women carrying things on their heads. Try to carry a suitcase on your head, and you’ll probably bite your tongue in concentration and wave your arms madly for balance. But African women walk for miles with heavy jugs of water or pots of food as if they weren’t carrying anything. Energetically speaking, they aren’t: researchers have found that the women can carry enormous loads without using any extra energy. They aren’t defying any laws of physics, though; they’re being good pendulums.
In 1977 a team of Harvard physiologists, in Kenya to study the locomotion of wild animals, found themselves distracted by the load- carrying women. When we tried to pick up the loads, they were just amazing, says Norman Heglund. We wondered how the devil they did it. As a first experiment, Heglund’s team ...
