Einstein Science Reporting for Kids
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16-Jun-2005

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Carrying stuff on your head in the Himalayas




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If you think hiking for an afternoon is a lot of work, imagine hiking for a week while carrying a pack from your head that weighs almost as much as you do.

High in the Himalayan Mountains in the country of Nepal, men, women and sometimes children working as "porters" transport heavy loads of cargo on their backs up and down steep footpaths to out-of-the-way places. For example, porters carry goods for about 100 kilometers from the Kathmandu valley to a bazaar in the town of Namche, Nepal near Mount Everest.

A group of scientists studied these porters and found that they use their heads to carry cargo while using a small amount of energy. The porters are even more energy efficient than African women who carry water and wood on their heads -- the only other group of people to be studied who use their heads to carry cargo. Both of these groups carry goods more efficiently than soldiers carrying backpacks.

These findings appear in the 17 June, 2005 issue of the journal Science.

Unlike western-style backpacks with two straps that loop around the shoulders and chest, the porters put their goods in a basket with a single strap that goes around the top of the head. This head strap, called a "namlo," connects to the basket called a "doko," which can be filled with goods. The porters carry a T-shaped stick or "tokma" that supports the basket when the porters rest.

Guillaume Bastien and his colleagues at the Université Catholique de Louvain in Belgium calculated how much energy the people burned when they carried loads of different weights and walked at different speeds.

To calculate how much energy the porters are using to carry their loads, the researchers measured how much oxygen they used and how much carbon dioxide they produced.

The porters walk slowly for many hours each day, take frequent rests and carry the greatest loads possible. The scientists are not sure how the porters are able to work so efficiently.

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