Height and intelligence

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Several epidemiological studies have shown a weak but statistically significant positive correlation between height and intelligence in human populations.[1][2][3][4] Similar associations have been found in early and late childhood and adulthood in both developed and developing countries, and associations persisted after controlling for social class and parental education. This does not imply that many short people are not intelligent, or that changes in physical height have a direct effect on cognitive ability. The reasons for this association remain unclear, but possible explanations include that height may be a biomarker of nutritional status or general mental and physical health during development, that genetic factors may influence both height and intelligence, or that both height and intelligence may be affected by adverse early environmental exposures.

Correlation[edit]

Studies of developing adolescents [5][6][7][8][9] and young adults[10][11] indicate a very small positive correlation between human IQ and height within national populations. The association is supported by studies linking height at eighteen with subsequent scholarly performance.[12]

Correlation coefficients in developing children are typically about 0.2. [13][14] A large study conducted on Norwegian soldiers the correlation between height and general ability was .15.[15] The effect appears to hold into the extremes of stature,[16] but may decrease with age.[17]

The correlation between the two factors is weak, although statistically significant. Consequently, these studies do not imply that variations in stature have a direct effect on cognitive ability. However, similar strength correlations have been found in early and late childhood in both developed and developing countries, even after controlling for social class and parental education. In adults, changes in environment and social status reduce the strength of this correlation.[17]

A recent study by Anne Case and Christina Paxson [18] has attracted media attention.[19][20]

Explanations of the correlation[edit]

The reasons for the association between height and intelligence remain unclear, but possible explanations include that height may be a marker of nutritional status, prenatal maternal stress, or general mental and physical health during development.

It has been suggested that the large increases in average height, assumed to be due to improved nutrition, have been accompanied by an increase in brain size which may be one explanation for the Flynn effect.[21]

Studies have shown, however, that common genetic factors influence variation in both height and intelligence, and are responsible for some of the effect,[22] or that both height and intelligence may be affected by adverse early environmental exposures. Two large recent twin pair studies of the height-intelligence relationship showed that both shared environment (59% in both studies) and shared genetics (35% in one study and 31% in the other) are responsible for significant portions of the observed correlation between intelligence and height.[11][15]

See also[edit]

References[edit]

  1. ^ Wilson DM, Hammer LD, Duncan PM et al. Growth and intellectual development. Pediatrics 1986;78:646–50.
  2. ^ Walker SP, Grantham-McGregor SM, Powell CA, Chang SM. Effects of growth restriction in early childhood on growth, IQ, and cognition at age 11 to 12 years and the benefits of nutritional supplementation and psychosocial stimulation. J Pediatr 2000; 137:36–41.
  3. ^ Tanner JM. Relation of body size, intelligence test scores and social circumstances. In: Mussen PH, Largen J, Covington M (eds). Trends and Issues in Developmental Psychology. New York: Holt, Rinehard and Winston Inc., 1969.
  4. ^ Pearce MS, Deary IJ, Young AH, Parker L. Growth in early life and childhood IQ at age 11 years: the Newcastle Thousand Families Study. Int J Epidemiol 2005;34:673–77.
  5. ^ Wilson DM, Hammer LD, Duncan PM et al. (1986). "Growth and intellectual development". Pediatrics 78 (4): 646–50. PMID 3763275. 
  6. ^ Walker SP, Grantham-McGregor SM, Powell CA, Chang SM. Effects of growth restriction in early childhood on growth, IQ, and cognition at age 11 to 12 years and the benefits of nutritional supplementation and psychosocial stimulation. J Pediatr 2000; 137:36–41. Abstract
  7. ^ Tanner JM. Relation of body size, intelligence test scores and social circumstances. In: Mussen PH, Largen J, Covington M (eds). Trends and Issues in Developmental Psychology. New York: Holt, Rinehard and Winston Inc., 1969.
  8. ^ Pearce MS, Deary IJ, Young AH, Parker L. "Growth in early life and childhood IQ at age 11 years: the Newcastle Thousand Families Study." Int J Epidemiol 2005;34:673–77.Article
  9. ^ Humphreys L. G., Davey T. C., Park R. K. (1985). "Longitudinal correlation analysis of standing height and intelligence". Child Development 56 (6): 1465–1478. doi:10.2307/1130466. JSTOR 1130466. PMID 4075869. 
  10. ^ Tuvemo T., Jonsson B., Persson I. (1999). "Intellectual and physical performance and morbidity in relation to height in a cohort of 18-year-old Swedish conscripts". Hormone Research 52 (4): 186–191. doi:10.1159/000023459. PMID 10725784. 
  11. ^ a b Beauchamp J. P., Cesarini D., Johannesson M., Lindqvist E., Apicella C. (2011). "On the sources of the height–intelligence correlation: New insights from a bivariate ACE model with assortative mating". Behavior Genetics 41 (2): 242–252. doi:10.1007/s10519-010-9376-7. PMC 3044837. PMID 20603722. 
  12. ^ [1] Patrik Magnusson, Finn Rasmussen et Ulf Gyllensten, International Journal of Epidemiology, 2006
  13. ^ Humphreys, L. G., Davey, T. C., & Park, R. K. (December 1985). "Longitudinal correlation analysis of standing height and intelligence". Child Development 56 (6): 1465–1478. doi:10.2307/1130466. JSTOR 1130466. PMID 4075869. 
  14. ^ Donald B. Egolf and Lloyd E. Corder (March 1991). "Height differences of low and high job status, female and male corporate employees". Sex Differences 5–6 (5–6): 365–373. doi:10.1007/BF00288309. 
  15. ^ a b Sundet JM, Tambs K, Harris JR, Magnus P, Torjussen TM. Resolving the genetic and environmental sources of the correlation between height and intelligence: a study of nearly 2600 Norwegian male twin pairs. Twin Res Hum Genet. 2005 Aug;8(4):307-11
  16. ^ Teasdale, TW; Owen DR, Sørensen TI (February 1991). "Intelligence and educational level in adult males at the extremes of stature". Hum Biol. (Wayne State University Press) 63 (1): 19–30. 
  17. ^ a b Teasdale T. W., Srensen T. I. A., Owen D. R. (1989). "Fall in association of height with intelligence and educational level". British Medical Journal 298 (6683): 1292–1293. doi:10.1136/bmj.298.6683.1292. PMC 1836522. PMID 2500201. 
  18. ^ Anne Case and Christina Paxson : Stature and Status: Height, Ability and Labor Market OutcomesArticle
  19. ^ [2] Success Is Relative, and Height Isn’t Everything, by Stephen S. Hall, New York times, November 28, 2006
  20. ^ [3] or [4]Taller People Are Smarter, Reuters, August 25, 2006
  21. ^ Neisser, U.; Boodoo, G.; Bouchard, T. J. , J.; Boykin, A. W.; Brody, N.; Ceci, S. J.; Halpern, D. F.; Loehlin, J. C.; Perloff, R.; Sternberg, R. J.; Urbina, S. (1996). "Intelligence: Knowns and unknowns". American Psychologist 51 (2): 77. doi:10.1037/0003-066X.51.2.77.  edit
  22. ^ Silventoinen K., Posthuma D., van Beijsterveldt T., Bartels M., Boomsma D.I. (2006). "Genetic contributions to the association between height and intelligence: evidence from Dutch twin data from childhood to middle age". Genes, Brain and Behavior 8: 585–595.