The article analyzes differences in brain size between races and their relationship to 37 musculoskeletal traits. The authors refer to the anthropological literature and suggest that these differences may affect IQ test scores. Using a method of weighing brains at autopsy, the famous French neurologist Paul Broca (1873) found that whites had heavier brains on average than blacks, with more complex curves and larger frontal lobes. (He confirmed the difference between blacks and whites using endocranial volume, and also found that East Asians had, on average, a larger cranial volume than whites.) Autopsy results have also stood the test of time. Later studies have shown that the average difference between blacks and whites is about 100 g Bean, 1906, Mall, 1909, Pearl, 1934, Vint, 1934. Some studies have shown that the greater the admixture of white blood (assessed independently of skin color), the greater the average brain mass in negroids Bean, 1906, Pearl, 1934. More recently, Ho, Roessmann, Straumfjord and Monroe (1980) found in an autopsy study of 1,261 adult Americans that 811 white Americans weighed an average of 1,323 g, while 450 negroid Americans weighed an average of 1,223 g - a difference of 100 g. Since the blacks and whites in the study were of similar body size, differences in body size cannot explain differences in brain weight.