Springy bamboo poles help villagers carry more than their own body weight

Southeast Asia is a riot of colour and biodiversity. Boasting luxuriant rainforest and thousands of insects and mammals, the region is ripe for a biologist in search of inspiration. But when James Croft, then at Edith Cowan University, Australia, went travelling, it wasn't the flora and fauna that caught his eye: it was the villagers carrying massive loads, sometimes more than their own body weight, on a bouncy bamboo pole slung across a shoulder. "I was curious how that evolved,' says Croft, adding, "I wondered if the springiness of the poles allowed them to transport the load more efficiently.' However, he also knew that the benefits of carrying loads on flexible poles was a bone of contention; some studies suggested the poles are beneficial, while others did not. Croft realised that many of the previous investigations had been carried out with pole-carrying novices, whereas the villagers that he had observed were true professionals, sometimes with decades of experience. After discussing the problem with John Bertram from the University of Calgary, Canada, Croft decided to return to Vietnam to find out whether experienced flexible pole carriers adapt the way they walk to help them carry heavy loads. The team publishes their discovery that villagers carrying a heavy load on a flexible pole could use 20% less energy than when using a rigid pole in Journal of Experimental Biology.