15 - 20 % above and below the mean
||Human Homo sapiens
||Haug H. Brain sizes, surfaces, and neuronal sizes of the cortex cerebri: a stereological investigation of man and his variability and a comparison with some mammals (primates, whales, marsupials, insectivores, and one elephant). Am J Anat. 1987 Oct180(2):126-42 DOI: 10.1002/aja.1001800203 abstract and p.127 right column top paragraphPubMed ID3673918
||Haug H.. Gegenbaurs Morphol. Jahrb., 130: 481-500 [Effect of secular acceleration on the human brain weight and its changes during aging]. [Article in German] Gegenbaurs Morphol Jahrb. 1984 130(4):481-500 AND Eggers R, Haug H, Fischer D. Preliminary report on macroscopic age changes in the human prosencephalon. A stereologic investigation. J Hirnforsch. 1984 25(2):129-39.PubMed ID6489725, 6736629
||Abstract: "This study deals with the stereological estimation of macroscopic sizes of brain and cortex, i.e., volume, surface, and folding, and of microscopic neuronal sizes, i.e., density, mean size, size distribution, and number of neurons." Primary source Eggers et al., 1984 abstract: "The studies here reported were performed on the prosencephalons of 12 human brains between 37 and 86 years of age having no signs of neuropathological alteration. The evaluation was carried out on serial frontal sections with a mean thickness of 5 mm with stereological point counting procedures for volume and surface area."
||Abstract: "The results show that the degree of variability in man amounts to about 15%." P.127 right column top paragraph: "The differences, however, are surely small, as shown by the estimation of the variance in man. The
variability in man is about 15-20% above and below the mean values (primary sources)."