Paranthropus robustus was a species of prehistoric human that lived in South Africa about 2 million years ago, alongside Homo ergaster, a direct ancestor of modern people. Fossils of Paranthropus robustus are found in abundance at Swartkrans Cave, situated about halfway between Johannesburg and Pretoria. Much has been revealed about the diet and social organization of this extinct species based on studies of its many skulls and hundreds of teeth, which have been recovered from Swartkrans since scientific excavations began there in 1948.