Sex and Age Variation in the Skin Color of Irish Children

Relethford, John H.; Lees, Francis C.; Byard, Pamela J.

doi:10.1086/203290

Cited by 7 publications

(4 citation statements)

References 7 publications

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“…These sex differences probably reflect tendencies for testosterone to increase pigmentation both in the skin and hair (Relethford, Lees, & Byard, 1985;Tobin, 2006) and in the iris of the eye (Coplan, Coleman, & Rubin, 1998). Given this evidence plus that which has implicated testosterone in influencing sexual orientation (see Ellis, 1996), we were surprised to find no statistical links between sexual orientation and either eye color or hair color.…”

Section: Discussionmentioning

confidence: 91%

Eye Color, Hair Color, Blood Type, and the Rhesus Factor: Exploring Possible Genetic Links to Sexual Orientation

et al. 2007

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The present study sought to expand the limited evidence that sexual orientation is influenced by genetic factors. This was accomplished by seeking statistical differences between heterosexuals and homosexuals for four traits that are known to be genetically determined: eye color, natural hair color, blood type, and the Rhesus factor. Using a sample of over 7,000 U.S. and Canadian college students supplemented with additional homosexual subjects obtained through internet contacts, we found no significant differences between heterosexuals and homosexuals regarding eye color or hair color. In the case of blood type and the Rh factor, however, interesting patterns emerged. Heterosexual males and females exhibited statistically identical frequencies of the A blood type, while gay men exhibited a relatively low incidence and lesbians had a relatively high incidence (p < .05). In the case of the Rh factor, unusually high proportions of homosexuals of both sexes were Rh- when compared to heterosexuals (p < .06). The findings suggest that a connection may exist between sexual orientation and genes both on chromosome 9 (where blood type is determined) and on chromosome 1 (where the Rh factor is regulated).

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Section: Discussionmentioning

confidence: 91%

Eye Color, Hair Color, Blood Type, and the Rhesus Factor: Exploring Possible Genetic Links to Sexual Orientation

et al. 2007

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“…Nonetheless, some of these genes are; thus, there should have been some selective pressure to make European skin color more sexually dimorphic. Yet skin color actually seems to be less sexually dimorphic in light-skinned populations (Relethford et al, 1985). The reason may be a ceiling effect.…”

Section: Discussionmentioning

confidence: 97%

European hair and eye color

Fröst¹

2006

Evolution and Human Behavior

143

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Human hair and eye color is unusually diverse in northern and eastern Europe. The many alleles involved (at least seven for hair color) and their independent origin over a short span of evolutionary time indicate some kind of selection. Sexual selection is particularly indicated because it is known to favor color traits and color polymorphisms. In addition, hair and eye color is most diverse in what used to be, when first peopled by hunter-gatherers, a unique ecozone of low-latitude continental tundra. This type of environment skews the operational sex ratio (OSR) of hunter-gatherers toward a male shortage in two ways: (1) men have to hunt highly mobile and spatially concentrated herbivores over longer distances, with no alternate food sources in case of failure, the result being more deaths among young men; (2) women have fewer opportunities for food gathering and thus require more male provisioning, the result being less polygyny. These two factors combine to leave more women than men unmated at any one time. Such an OSR imbalance would have increased the pressures of sexual selection on early European women, one possible outcome being an unusual complex of color traits: hair-and eye-color diversity and, possibly, extreme skin depigmentation.

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“…Indeed, Byard (1981, p. 132) noted that the fact that samples of different age composition have been compared has contributed to a ''confusing picture of sex differences in pigmentation'' (see also Kalla 1973Kalla , 1974. We acknowledge that we are relying on other authors' statements that their subjects are adults, and that our decision to exclude children and teenagers caused us to discard a good number of papers (e.g., Byard and Lees, 1982;Carbonnel and Olivier, 1966;Chamla and Demoulin, 1978;Clark et al, 1981;Conway and Baker, 1972; Greksa, 1998a,b;Harrison and Owen, 1964;Harrison and Salzano, 1966;Harrison et al, 1967;Harvey and Lord, 1978;Hulse, 1967Hulse, , 1973Kalla, 1973;Kalla and Tiwari, 1970;Lasker, 1954;Ojikutu, 1974;Omoto, 1968;Park and Lee, 2005;Relethford et al, 1985;Rebato et al, 1993;Smith and Mitchell, 1973;Sunderland and Coope, 1973;Sunderland and Woolley, 1982;Walsh, 1963; Wasserman and Heyl, 1968;Weiner et al, 1963). Our sample is smaller than that used by Relethford (1997Relethford ( , 2000 because he used male-only data sets, and we excluded papers which only reported data on one gender or which pooled male and female data (Bü chi, 1957(Bü chi, /1958Caro, 1980;Das and Mukherjee, 1963;Ducros et al, 1975;Eriksson et al, 1980;Garrard et al, 1967;Harrison and Owen, 1964;…”

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confidence: 99%

Human skin‐color sexual dimorphism: A test of the sexual selection hypothesis

Madrigal

Kelly

2006

American J Phys Anthropol

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Applied to skin color, the sexual selection hypothesis proposes that male preference for light-skinned females explains the presence of light skin in areas of low solar radiation. According to this proposal, in areas of high solar radiation, natural selection for dark skin overrides the universal preference of males for light females. But in areas in which natural selection ceases to act, sexual selection becomes more important, and causes human populations to become light-skinned, and females to be lighter than males. The sexual selection hypothesis proposes that human sexual dimorphism of skin color should be positively correlated with distance from the equator. We tested the prediction that sexual dimorphism should increase with increasing latitude, using adult-only data sets derived from measurements with standard reflectance spectrophotometric devices. Our analysis failed to support the prediction of a positive correlation between increasing distance from the equator and increased sexual dimorphism. We found no evidence in support of the sexual selection hypothesis.

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Sex and Age Variation in the Skin Color of Irish Children

Cited by 7 publications

References 7 publications

Eye Color, Hair Color, Blood Type, and the Rhesus Factor: Exploring Possible Genetic Links to Sexual Orientation

Eye Color, Hair Color, Blood Type, and the Rhesus Factor: Exploring Possible Genetic Links to Sexual Orientation

European hair and eye color

Human skin‐color sexual dimorphism: A test of the sexual selection hypothesis

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