Exemplar: Sangiran 17 before cleaning [top], after cleaning [bottom] - c.800,000 y.a.HOMO ERECTUS represents a long line of fossils found in eastern Africa, the Middle East and southern and southeastern Asia (where the fossils are called Java Man) from about 1.7 million to 200,000 years ago.
Erectus shows a gradual lightening of the ergaster features, though many similarities in the skulls (pronounced browridges and an elongated brain case) persist. Indeed, some of the erectus modifications are adaptations for heavy chewing power, and in that sense reflect a radiation into the ecological niches and diets dominated in Africa by the australopithecines.
Body size remains on a par with ergaster: males were about 1.8 meters and 63 kilos; females 1.6 meters and 53 kilos. Like ergaster, the face has protruding jaws with large molars, no chin, thick brow ridges, and a long low skull. Brain capacity increased gradually throughout the erectus line, from a range of 800cc to 1060cc at the time erectus first appeared to a range of 1060cc to 1300cc around the time it went extinct.
The evolutionary relation between ergaster and erectus is unclear: some experts treat them as early and late forms of the same species. It's more likely that erectus evolved first in Africa from an ergaster ancestor, then migrated after ergaster into other parts of Africa and the Middle East, then into China and southern Asia (as far as Java and Borneo).
Despite its long survival and continually increasing brain size -- and cultural advances that included geographic dispersion throughout southern Asia, the domestication of fire, refinement to Acheulean tools, and long-term cave habitation -- erectus is apparently a specialization of ergaster that is not a precursor to modern human populations.