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Brain size and encephalization in early to Mid‐Pleistocene Homo
Author(s) -
Rightmire G. Philip
Publication year - 2004
Publication title -
american journal of physical anthropology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.146
H-Index - 119
eISSN - 1096-8644
pISSN - 0002-9483
DOI - 10.1002/ajpa.10346
Subject(s) - homo erectus , crania , brain size , pleistocene , encephalization , early pleistocene , paleontology , human evolution , geography , biology , evolutionary biology , archaeology , medicine , radiology , magnetic resonance imaging
Important changes in the brain have occurred during the course of human evolution. Both absolute and relative size increases can be documented for species of Homo , culminating in the appearance of modern humans. One species that is particularly well‐represented by fossil crania is Homo erectus . The mean capacity for 30 individuals is 973 cm 3 . Within this group there is substantial variation, but brain size increases slightly in specimens from later time periods. Other Middle Pleistocene crania differ from those of Homo erectus . Characters of the facial skeleton, vault, and cranial base suggest that fossils from sites such as Arago Cave in France, the Sima de los Huesos in Spain, Bodo in Ethiopia, Broken Hill in Zambia, and perhaps Dali in China belong to the taxon Homo heidelbergensis . Ten of these mid‐Quaternary hominins have brains averaging 1,206 cm 3 in volume, and many fall beyond the limits of size predicted for Homo erectus of equivalent age. When orbit height is used to construct an index of relative brain size, it is apparent that the (significant) increase in volume documented for the Middle Pleistocene individuals is not simply a consequence of larger body mass. Encephalization quotient values confirm this finding. These changes in absolute and relative brain size can be taken as further corroborative evidence for a speciation event, in which Homo erectus produced a daughter lineage. It is probable that Homo heidelbergensis originated in Africa or western Eurasia and then ranged widely across the Old World. Archaeological traces indicate that these populations differed in their technology and behavior from earlier hominins. Am J Phys Anthropol, 2003. © 2003 Wiley‐Liss, Inc.