Palla Ákos szerk.: Az Országos Orvostörténeti Könyvtár közleményei 37. (Budapest, 1965)

Tóth Tibor: The Variability of the Brain-Weight by Homo

of social hygiene encourages the study of sexual dimorphism as expressed by intersexual heterochronia (Table 4). It should be noted that contrary to formerly mentioned partial deviation, may data on the normal category corresponds—for the most part — to the results of Roessle-Roulet (e. g., the average maximum brain weight, the great reduction of intersexual difference in the weight of the brain until the end of old age, the harmonic feature of weight reduction), (Table 4). Otherwise, it is significant that irrespective of the relatively great number of cases all of my observations have to be regarded as provisional and characteristic of only a relatively small geographical unit; consequently I am unwilling to make generalizations at an ecumenical validity (L e., for a larger population). The conclusions of my analysis may be summarized as follows: 1. The variability of the weight of the brain during the adult period (between 20—100 years) of postnatal ontogenesis is merely the elementary quantitative manifestation of biological microevolution. 2. Sexual dimorphism examinable through the average values of the brain weight for genus Homo is one of the constituents of the generally greater, morphophysiological gracility of the female organism and it is expressed by: a) the relative smallness of the average normal brain weight, b) by the circumstance that the weight of the female brain reaches its maximum approximately ten years sooner, and c) by the regressive acceleration occuring also ten years sooner. These two latter phenomena are in a direct morphophysiological relation. 3. The study of the problematics of the great individual variability of the weight, the mass of the brain, requires the analysis of a great number of cases.