Abstract:

Ancient human skulls exhibit anatomical and morphological differences from modern skulls that depend on the evolutionary stage of the fossil under study. Thus, formulae derived using modern human skull measurements are mostly unsuitable for calculating cranial capacities from ancient human fossils. The most accurate way to estimate cranial capacities of human fossil skulls is through internal cranial vault reconstructions; However, due to the complex reconstruction process of endocranial casts, as well as the rare and almost never fully intact fossil skulls, prompting an intense search by paleoanthropologists for better methods for estimating ancient human values. Here, cranial capacity methods for their estimation from Chinese human fossils were compared and analyzed, with the following results: 1) Anatomical features of early modern humans and modern humans are basically similar. Thus, the regression equation derived using modern human skull measurements to estimate cranial capacity applies to early modern human fossils; 2) Homo erectus’ thick skull and low cranium differ markedly from corresponding modern human features. Therefore, instead of the modern human formula, the regression equation derived here from Chinese Homo erectus skull measurements, C=-1301.944+60606L+0.718b+9.936h, should be used to calculate Homo erectus cranial capacity. Using this formula, the cranial capacity of the Lantian Homo erectus was estimated to be 918 mL, as compared to the previous estimate of 778 mL; 3) Physical features of archaic Homo sapiens, which lie somewhere between those of Homo erectus and early modern humans, vary markedly from these extremes; therefore their cranial capacities cannot be estimated using a single formula. For example, cranial capacities of archaic human fossils Dali and Hualongdong 6, which exhibit physical characteristics more closely resembling those of Homo erectus than those of early modern humans, are best calculated using the Homo erectus formula. Conversely, cranial capacities of archaic human fossils possessing physical characteristics closer to early modern humans than to Homo erectus, such as Xuchang 1, should be estimated using the modern human formula. In yet a third scenario, cranial capacities of fossils exhibiting physical characteristics between those of Homo erectus and early modern humans, such as Maba and Jinniushan, should be calculated using averages of values obtained using both modern human and Homo erectus formulae.

Key words: Cranial capacity, Formulae, Modern human, Homo erectus, Archaic Homo sapiens, Endocast