A Prehistoric Crossroads
The Drimolen paleocave system, part of the Cradle of Humankind UNESCO World Heritage Site, holds a record of an important time in human evolution. Excavations at the site known as the Drimolen Main Quarry (DMQ) have uncovered fossil evidence showing that three distinct early human genera—Homo, Paranthropus, and Australopithecus—coexisted on the same land between 2.04 and 1.95 million years ago. This discovery challenges the linear model of human evolution, showing a more complex picture of multiple hominin lineages living together.
The site was discovered on July 9, 1992, by Andre Keyser. Since then, it has yielded over 200 hominin specimens. The age of the fossils has been determined using a combination of dating methods, including uranium-lead, uranium-series electron spin resonance (US-ESR), and palaeomagnetism. These techniques pinpointed a geomagnetic reversal recorded in the cave's sediments, which corresponds to the base of the Olduvai SubChron at approximately 1.95 million years ago. This precise dating makes Drimolen one of the most accurately dated early hominin sites in Southern Africa.
The cave's deposits formed rapidly, over a period of about 90,000 years, as sediment and animal remains washed down a vertical cave entrance. This quick accumulation records the fauna and hominins present during this specific window of time.
The Inhabitants of Drimolen
Among the finds at Drimolen are the crania of Homo erectus and Paranthropus robustus. The partial cranium DNH 134, belonging to a Homo erectus child aged between two and three years old, is the oldest known fossil of this species in the world. Its discovery pushes back the first appearance of H. erectus by at least 100,000 to 200,000 years. Before this find, it was widely assumed that H. erectus originated in eastern Africa. The DNH 134 fossil suggests a possible southern African origin for our direct ancestor.
Living alongside H. erectus was Paranthropus robustus, a "cousin" species not in our direct lineage. P. robustus was characterized by large teeth and powerful jaws, adapted for eating tough or hard foods. Several important P. robustus skulls have been found at Drimolen, including DNH 7 ("Eurydice"), the most complete female skull of the species ever found, and DNH 155, a well-preserved male cranium. The discovery of the DNH 155 male skull has challenged previous ideas about the species. It suggests that anatomical differences once attributed to sex may instead be evidence of rapid evolution within the species in response to local climate change.
The presence of these two very different species—large-brained, small-toothed H. erectus and small-brained, large-toothed P. robustus—shows two divergent evolutionary paths. Drimolen is also one of the few sites where these two species have been found together, allowing researchers to study their contemporaneous existence.