Consuming the meat of large animals is generally thought to have been instrumental in human evolution. It allowed early hominins, such as australopithecines, to begin developing larger brains some 3.4 million years ago. At a time when early hominins were not yet able to manufacture and hunt with sophisticated tools, however, obtaining meat from animals that significantly outweighed them was a dangerous undertaking. Researchers now believe that our human ancestors may have first acquired the taste for meat by scavenging carcasses left behind by other predators. Even if most of the meat was rotten or had already been consumed, early hominins may have used stones and other tools to smash open bones and access fatty marrow deposits, an invaluable source of the nutrients required by their very large brains. “Targeting marrow not only enables a stone-wielding hominin to access a novel resource that can’t be accessed by most other carnivores, but it was a relatively low-risk food,” says Yale University paleoanthropologist Jessica Thompson. This combination of high caloric returns at a low cost may have served as the ideal gateway to a long-standing carnivorous habit.