The brain size of hominids has increased approximately threefold during the evolution of the hominids fromAustralopithecus toHomo sapiens. It is proposed that the principal reason for this increase is that larger brains conferred greater intelligence, and greater intelligence conferred a selection advantage.
A number of anthropologists have difficulty accepting this thesis because they believe that brain size is not associated with intelligence in man. Evidence is reviewed, and new evidence from two studies is presented, to show that brain size as measured by head size is positively correlated with intelligence as measured by intelligence tests. On two recent samples statistically significant correlations of .21 and .30 were obtained between estimates of brain size and IQ. It is considered that brain size is positively associated with intelligence in man and that this is the major reason for the increase in brain size of the hominids during the last 3.2 million years.
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Agrawai N., Sinha S.N. &Jensen A.R., 1984.Effects of inbreeding on Raven's matrices. Behavior Genetics, 14: 579–585.
Bashi J., 1977.Effects of inbreeding on cognitive performance. Nature, 266: 440–442.
Brandt I., 1978.Growth dynamics of low birth weight infants with emphasis on the perinatal period. In: Human Growth Vol 2 F. Falkner and J. M. Tanner, Eds. Plenum, New York.
Broman S.H., Nichols P.L. &Kennedy W.A., 1975.Preschool IQ, New York and London: J. Wiley.
Cohen T., Block N., Flum Y., Kadar M. &Goldschmidt E., 1969.School attainments in an immigrant population. In The Genetics of Migrant and isolate populations. E. Goldschmidt (ed). Williams and Wilkins, Baltimore.
Engsner G., 1974.Brain growth and motor nerve conduction velocity in children with protein-calorie malnutrition. Acta Universitatis Upsaliensis, 1–60.
Fisher R.A., 1930.The Genetical Theory of Natural Selection. Clarendon Press, Oxford.
Henneberg M., 1987.Hominid cranial capacity change through time: a darwinian process. Human Evolution, 2: 213–220.
Henneberg M., Budnik A., Pezacka M. &Puch A.E., 1985.Head size, body size and intelligence: intraspecific correlations in Homasapiens sapiens. Homo, 36: 207–218.
Jensen A.R., 1983.Effects of inbreeding on mental-ability factors. Person. Indiv. Diff., 4: 71–87.
Jerison H.J., 1982.The evolution of biological intelligence. In: Handbook of Human Intelligence. R.J. Sternberg, Ed. Cambridge University Press, Cambridge.
Kohler W., 1925.The Mentality of Apes. Harcourt, Brace and World, New York.
Latham M.C., 1974.Protein-calorie malnutrition in children and its relation to psychological development and behaviour. Physiol Rev, 54: 541–565.
Mackintosh N.J., Wilson B., &Boakes R.A., 1985.Differences in mechanisms of intelligence among vertebrates. Philosophical Transactions of the Royal Society of London, 8: 308, 53–65.
Murdoch J. &Sullivan L.R., 1923.A contribution to the study of mental and physical measurements in normal school children. American Physical Education Review, 28: 209–215, 276–280, 328–330.
Passingham R.E., 1979.Brain size and intelligence in man. Brain, Behaviour and Evolution, 16: 253–270.
Pearl R., 1906.On the correlation between intelligence and the size of the head. J. of Comp. Neurol. Psychol., 16: 189–199.
Pearson K., 1906.On the relationship of intelligence to size and shape of head, and to other physical and mental characters. Biometrika, 5: 105–146.
Plomin R., 1987.The genetics of intelligence. In: Arthur Jensen, Consensus and Controversy. S. Mogdil and C. Mogdil (eds), Falmer Press, London.
Schreider E., 1968.Quelques correlations somatiques des tests mentaux. Homo, 19: 38–43.
Susanne C. &Sporog J., 1973.Etude de correlations existant entre des tests psychotechniques et des mensurations cephaliques. Bulletin Societe Royal Belge Anthropologie et Prehistorie, 84: 59–63.
Weinberg W.A., Dietz S.G., Penick E.C. &McAlister W.H., 1974.Intelligence, reading achievement, physical size and social class. J. Pediatrics, 85: 482–489.
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Lynn, R. The evolution of brain size and intelligence in man. Hum. Evol. 5, 241–244 (1990). https://doi.org/10.1007/BF02437240
- brain size
- hominid evolution