Throughout the evolutionary history of H. erectus there is substantial evidence for selection leading towards increased encephalization, so that while early members of the lineage have a cranial capacity of 600-800 cm3, the cranial capacities of most later specimens are well in excess of 1000 cm3, which is within the lower range of contemporary humans, without appearing considerably larger in body size than early H. erectus.
As the body size of hominins increases, the brain size increases as well (Ruff et al. 1997). While the smallest-bodied early H. erectus fossils have brain sizes only slightly larger than earlier hominins (australopiths), early large-bodied specimens, such as the Nariokotome individual, have a brain volume greater than 800 cm3, more than 50% larger than earlier australopiths (and about 60% of the typical brain size of someone living today). However, in addition to the absolute increase in brain volume that accompanies an increase in body size, there is also a proportional increase. This is referred to as encephalization, and is an important characteristic of H. erectus. Throughout the evolutionary history of H. erectus there is substantial evidence for selection leading towards increased encephalization, so that while early members of the lineage have a cranial capacity of 600-800 cm3, the cranial capacities of most later specimens are well in excess of 1000 cm3, which is within the lower range of contemporary humans, without appearing considerably larger in body size than early H. erectus.