Variability hypothesis

The variability hypothesis, also known as the greater male variability hypothesis, is the hypothesis that human males generally display greater variability in traits than human females do. It has often been discussed in relation to human cognitive ability, where some studies appear to show that males are more likely than females to have either very high or very low IQ test scores. In this context, there is controversy over whether such sex-based differences in the variability of intelligence exist, and if so, whether they are caused by genetic differences, environmental conditioning, or a combination of both.

The variability hypothesis, also known as the greater male variability hypothesis, is the hypothesis that human males generally display greater variability in traits than human females do. It has often been discussed in relation to human cognitive ability, where some studies appear to show that males are more likely than females to have either very high or very low IQ test scores. In this context, there is controversy over whether such sex-based differences in the variability of intelligence exist, and if so, whether they are caused by genetic differences, environmental conditioning, or a combination of both.

Leta Hollingworth's studies

By examining the case records of 1,000 patients at the Clearing House for Mental Defectives, Leta Hollingworth determined that, although men outnumbered women in the clearing house, the ratio of men to women decreased with age. Hollingworth explained this to be the result of men facing greater societal expectations than women. Consequently, deficiencies in men were often detected at an earlier age, while similar deficiencies in women might not be detected because less was expected of them. Therefore, deficiencies in women would be required to be more pronounced than those in men in order to be detected at similar ages. Hollingworth also attacked the variability hypothesis theoretically, criticizing the underlying logic of the hypothesis. Hollingworth argued that the variability hypothesis was flawed because: (1) it had not been empirically established that men were more anatomically variable than women, (2) even if greater anatomical variability in men were established this would not necessarily mean that men were also more variable in mental traits, (3) even if it were established that men were more variable in mental traits this would not automatically mean that men were innately more variable, (4) variability is not significant in and of itself, but rather depends on what the variability consists of, and (5) that any possible differences in variability between men and women must also be understood with reference to the fact that women lack the opportunity to achieve eminence because of their prescribed societal and cultural roles at the time. Additionally, the argument that great variability automatically meant greater range was criticized by Hollingworth. In an attempt to examine the validity of the variability hypothesis, while avoiding intervening social and cultural factors, Hollingworth gathered data on birth weight and length of 1,000 male and 1,000 female newborns. This research found virtually no difference in the variability of male and female infants birth weight, and it was concluded that if variability favored any sex, it was the female sex. The general consensus today is that boys have a higher birth weight than girls, and are more responsive to their mother's diet while in the womb, thus causing an even greater variation if nutritional needs are met.

Modern studies

The 21st century has witnessed a resurgence of research on gender differences in variability, with most of the emphasis on humans. The results vary based on the type of problem, but some recent studies have found that the variability hypothesis is true for parts of IQ tests, with more men falling at the extremes of the distribution. Publications differ as to the extent and distribution of male variability, including on whether variability can be shown across various cultural and social factors.

Contemporary controversies

In a 1992 paper titled "Variability: A Pernicious Hypothesis", Stanford Professor Nel Noddings discussed the social history which she argued explains "the revulsion with which many feminists react to the variability hypothesis." In 2005, then Harvard President, Larry Summers, addressed the National Bureau of Economic Research Conference on the subject of gender diversity in the science and engineering professions, saying: "It does appear that on many, many different human attributes—height, weight, propensity for criminality, overall IQ, mathematical ability, scientific ability—there is relatively clear evidence that whatever the difference in means—which can be debated—there is a difference in the standard deviation, and variability of a male and a female population." His remarks caused a backlash; Summers faced a no-confidence vote from the Harvard faculty, prompting his resignation as President. In 2017, a mathematics research paper by Theodore P. Hill and Sergei Tabachnikov, presenting a possible evolutionary explanation for the variability hypothesis, was peer-reviewed, accepted, and formally published in The New York Journal of Mathematics. Three days later, that article was removed and replaced by an unrelated article by different authors. This caused debate within the scientific community and international publicity. A revised version was subsequently peer-reviewed again and published in the Journal of Interdisciplinary Mathematics. However, recent genetic empirical studies have found no evidence supporting the proposition that the 'averaging' effect of X-inactivation in females results in greater variability in male cognitive ability, https://pubmed.ncbi.nlm.nih.gov/22843342/

See also

Sex differences in humans Sex and psychology Bateman's principle Lek paradox Sexual dimorphism Dual-mating strategy

References

Text derived from https://en.wikipedia.org/w/index.php?oldid=1375094693 under CC BY-SA 4.0; modifications have been made.