Robert Atkins wrote in The New Diet Revolution of our ancestors “eating the fish and animals that scampered and swam around him, and the fruits and vegetables and berries that grew nearby.” This makes intuitive sense, but where’s the evidence? This presentation considers the fossils themselves and what they can teach us about the diets of our early hominin forebears. It focuses on a key part of human evolution, when our ancestors and near cousins, the australopiths, began to descend from the trees. By about four million years ago, Australopithecus had evolved thicker, flatter, relatively larger teeth than their predecessors, suggesting a change in diet from soft foods, like forest fruits, to harder or tougher ones, like nuts or leaves. Then, about 2.5 million years ago, as forest began to give way to savanna, there was a fork in the evolutionary road. One direction led to Paranthropus, our near-cousins, with even more specialized teeth and jaws. The other led to the earliest members of our own biological genus, Homo, and a reversal of this trend. Evidence from tooth chemistry and microscopic wear suggests that some species had increasingly specialized diets, but others, including those of early Homo, ate a broader variety of foods.