Peking Man (Homo erectus pekinensis) is a subspecies of H. erectus which inhabited the Zhoukoudian cave site in modern northern China during the Chibanian. The first fossil, a tooth, was discovered in 1921, and the Zhoukoudian Cave has since then 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 for decades to come. The fossils became the centre of anthropological discussion, and were classified as a direct human ancestor, propping up the Out of Asia hypothesis that humans evolved in Asia. Peking Man also played a vital role in the restructuring of the Chinese identity following the Chinese Communist Revolution, and was intensively communicated to working class and peasant communities to introduce them to Marxism and science (overturning deeply-rooted superstitions and creation myths). Early models of Peking Man society strongly leaned towards communist or nationalist ideals, leading to discussions on primitive communism and polygenism. This produced a strong schism between Western and Eastern interpretations, especially as the West adopted the Out of Africa hypothesis by late 1967, and Peking Man's role in human evolution diminished as merely an offshoot of the human line. Though Out of Africa is now the consensus, Peking Man interbreeding with human ancestors is frequently discussed especially in Chinese circles.
Peking Man is characterised by a long and heavily fortified skull, featuring an inflated bar of bone circumscribing the crown, crossing along the brow ridge, over the ears, and connecting at the back of the skull, as well as a sagittal keel running across the midline. The bone of the skull and long bones is exorbitantly thickened. The face was protrusive (midfacial prognathism), eye sockets wide, jaws robust and chinless, and teeth large. Brain volume ranged from 850 to 1,225 cc, for an average of just over 1,000 cc (compared to an average of 1,270 cc for present-day modern males and 1,130 for present-day modern females).