All these species dated to the Pleistocene and were found in the same general vicinity (now called the "Cradle of Humankind"). Broom considered them evidence of a greater diversity of hominins in the Pliocene from which they and modern humans descended, and consistent with several hominin taxa existing alongside human ancestors.

The Kromdraai taxon, classified as Paranthropus robustus, was later discovered at the nearby