Today scientists consider Homo erectus to include skeletal remains from Africa and Asia across a long period of the Pleistocene epoch. The African examples of this species are all Early Pleistocene in age, with the oldest specimen around 2 million years old from Drimolen, South Africa, and the most recent approximately 800,000 years old from Olduvai Gorge, Tanzania.

This virtual lab includes two crania of H. erectus together with a cranium of a modern human and the Sts 5 cranium of Australopithecus africanus for comparison. The two H. erectus fossils are KNM-ER 3733 and KNM-ER 3883. Both come from the fossil exposures on the eastern side of Lake Turkana, Kenya, and both represent individuals that lived sometime between 1.65 and 1.5 million years ago.

These two fossil H. erectus crania are similar in many ways, and they reflect the morphology of other African examples of H. erectus. Some aspects of these skulls separate them from any examples of Australopithecus:

• Brain size. Compared to Australopithecus, the brain size represented by these H. erectus skulls is substantially larger: around 850 ml in KNM-ER 3733 and 780 ml in KNM-ER 3883, compared to around 485 ml in the Sts 5 skull.
• Supraorbital torus. H. erectus skulls express a torus, or a bar of bone, extending across the top of both orbits. This may form an arched shape over each orbit, or may be quite straight.
• Supratoral sulcus. The supraorbital torus in many H. erectus skulls, like these, is separated from the forehead portion of the frontal bone (called the frontal squama) by a groove, running from left to right above the torus. This supratoral sulcus delineates the upper face from the vault.
• Projecting nose. The nasal bones of H. erectus project slightly forward from the profile of the face. This is a contrast to the flat upper face of Australopithecus.
• Reduced prognathism. The lower face of H. erectus does not project forward as extensively as in Australopithecus.

Not all features of the H. erectus skull are humanlike. The vault is much shorter than in modern humans, with a smaller brain size. H. erectus crania both have their maximum width across the temporal bones near the base of the skull, as in Australopithecus. The muscle attachments on the skull are larger and more prominent than in most recent humans, and the premolar and molar teeth are somewhat larger, although smaller than in Australopithecus.

Materials in this lab

• The original KNM-ER 3733 and KNM-ER 3883 crania are curated at the Nairobi National Museum, Nairobi, Kenya. The models in this laboratory are based upon data from casts in the Biological Anthropology collection at UW-Madison. High-quality 3D scans of these two crania are available from AfricanFossils.org. Those models are compatible with 3D printing and classroom use.
• The original Sts 5 fossil is curated at the Ditsong Museum of Natural History in Pretoria, South Africa. The model in this virtual lab is based upon a data from a cast in the Biological Anthropology collection of UW-Madison.
• The model of the human calvaria is based on an anatomical model created by Hannah Newey. The model is available on Sketchfab with a Creative Commons Non-Commercial Share-alike (CC-BY-NC-SA) license. I reduced the polygon count of the model for this virtual lab.

Back to full list of virtual labs