Here, as in Homo habilis, there is an increase in brain size. The average brain size was between 750 cm3 and 1250 cm3. This shows an overall increase of 40 % from Homo habilis.Cranial shape reflects the brain size increase by thickening of the cranial walls. The supraorbital tori (brow ridges) become larger and there is a projection of the nuchal torus (base of the skull). Due to widening at the base of the skull and a maximum breath below the ear openings, the scull has a pentagonal contour. There is little forehead development.
There is a large increase in body size. From the information of the Nariokotome skeleton adults weighted well over 100 pounds with a mean height of 5.6 feet. There was a large amount of sexual dimorphism, where males were much larger in comparison to females. There was also an increase in robusticity. Dentition shows a trend towards larger teeth, with the incisor teeth on the back having a scooped out shoveled look.