How Chimps Make Their Beds

Chimpanzees choose tree branches that give them the most firm and stable place to sleep, a new study says. What's more, the research bolsters the theory that high-quality sleep may have led to the evolution of modern humans, said study leader David Samson, an anthropologist at the University of Nevada, Las Vegas. Chimpanzees build their beds—called nests—in tree canopies using branches that they harvest from specific tree species. They spend about eight to nine hours a night on these platforms. But until the recent study, published April 16 in the journal PLOS ONE, scientists didn't know how they selected the building materials. Samson and his colleagues measured the stiffness and bending strength of seven tree species most commonly used by chimps in the Toro-Semliki Wildlife Reserve in western Uganda. The team also looked at the surface area of the leaves on the trees and the structure of each tree species. What they found was remarkable.