A wild chimpanzee eats a tortoise, scooping out the meat after cracking the hard shell against a tree trunk, at the Loango national park on the coast of Gabon, in this photo provided by the Max Planck Institute. Researchers from the institute and the University of Osnabrück said they had spotted the unusual behaviour dozens of times in a group of chimpanzees. (Photo by Erwan Theleste/AP Photo)
