Endocranial capacity of the Bodo cranium determined from three-dimensionalcomputed tomography

The 600,000-year-old cranium from Bodo, Ethiopia, is the oldest and most co mplete early Middle Pleistocene hominid skull from Africa. "Virtual endocas t" models created by three-dimensional computed tomography (CT) techniques indicate an endocranial capacity of about 1,250 cc for this cranium (with a reasonable range between similar to 1,200-1,325 cc, depending on how missi ng portions of the basicranial region are reconstructed). From these determ inations, several important implications emerge concerning current interpre tations of "tempo and mode" in early hominid brain evolution: 1) already by the early Middle Pleistocene, at least one African hominid species, Home h eidelbergensis, had reached an endocranial capacity within the normal range of modern humans; 2) in spite of its large endocranial capacity, estimates of Bodo's encephalization quotient fall below those found in a large sampl e of Homo sapiens (both fossil and recent) and Neandertals; and 3) the grea test burst of brain expansion in the Homo lineage may not have been in the last several hundred thousand years, but; rather much earlier in the Lower to early Middle Pleistocene. (C) 2000 Wiley-Liss, Inc.