The porters of Nepal are famous for being the most spectacular haulers of head-supported loads in the world. They trek up and down steep mountain trails, sometimes for hundreds of kilometres, while carrying goods in a basket supported by a strap across their foreheads. Often the loads exceed the porter's own body weight. A study in this week's Science shows that Nepalis carry loads more economically than any other group previously studied1. They expend less energy per load than both Westerners with backpacks and African women who carry baskets on their heads, either directly or with a strap. The team, led by Norman Heglund, a physiologist at the Catholic University of Louvain in Belgium, are not sure exactly how the porters manage to be so efficient. It is known that they usually walk with a slow pace and take frequent breaks, sometimes resting for 45 seconds out of every minute on a steep climb. But the porters are also efficient when walking at a steady pace, the team found. Perhaps they alter their gait to somehow reduce muscular work, the researchers guess, or in some other way increase their efficiency.