H. erectus in the context of Dmanisi hominins

Homo ergaster is an extinct species or subspecies of archaic humans who lived in Africa in the Early Pleistocene. Whether H. ergaster constitutes a species of its own or should be subsumed into H. erectus is an ongoing and unresolved dispute within palaeoanthropology. Proponents of synonymisation typically designate H. ergaster as "African Homo erectus" or "Homo erectus ergaster". The name Homo ergaster roughly translates to "working man", a reference to the more advanced tools used by the species in comparison to those of their ancestors. The fossil range of H. ergaster mainly covers the period of 1.7 to 1.4 million years ago, though a broader time range is possible. Though fossils are known from across East and Southern Africa, most H. ergaster fossils have been found along the shores of Lake Turkana in Kenya. There are later African fossils, some younger than 1 million years ago, that indicate long-term anatomical continuity, though it is unclear if they can be formally regarded as H. ergaster specimens. As a chronospecies, H. ergaster may have persisted to as late as 600,000 years ago, when new lineages of Homo arose in Africa.

Those who believe H. ergaster should be subsumed into H. erectus consider there to be too little difference between the two to separate them into distinct species. Proponents of keeping the two species as distinct cite morphological differences between the African fossils and H. erectus fossils from Asia, as well as early Homo evolution being more complex than what is implied by subsuming species such as H. ergaster into H. erectus. Additionally, morphological differences between the specimens commonly seen as constituting H. ergaster might suggest that H. ergaster itself does not represent a cohesive species. Regardless of their most correct classification, H. ergaster exhibit primitive versions of traits later expressed in H. erectus and are thus likely the direct ancestors of later H. erectus populations in Asia. Additionally, H. ergaster is likely ancestral to later hominins in Europe and Africa, such as modern humans and Neanderthals.

Peking Man (Homo erectus pekinensis, originally "Sinanthropus pekinensis") is a subspecies of H. erectus which inhabited what is now northern China during the Middle Pleistocene. Its fossils have been found in a cave some 50 km (31 mi) southwest of Beijing (referred to in the West as Peking upon its first discovery), known as the Zhoukoudian Peking Man Site. The first fossil, a tooth, was discovered in 1921, and Zhoukoudian has since become the most productive H. erectus site in the world. Peking Man was instrumental in the foundation of Chinese anthropology, and fostered an important dialogue between Western and Eastern science. Peking Man became the centre of anthropological discussion, and was classified as a direct human ancestor, propping up the Out of Asia theory that humans evolved in Asia.

Peking Man also played a vital role in the restructuring of Chinese identity following the Chinese Communist Revolution, and it was used to introduce the general populace to Marxism and science. Early models of Peking Man society were compared to communist or nationalist ideals, leading to discussions on primitive communism and polygenism (that Peking Man was the direct ancestor of Chinese people). This produced a strong schism between Western and Eastern interpretations of the origin of modern humans, especially as the West adopted the Out of Africa theory in the late 20th century, which described Peking Man as an offshoot in human evolution. Though Out of Africa is now the consensus, Peking Man interbreeding with human ancestors is still discussed.