Digit Ratio: A Pointer to Fertility, Behavior, and Health

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Rutgers University Press, 2002 - Science - 173 pages
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Could the length of your fingers indicate a predisposition to breast cancer? Or musical genius? Or homosexuality? In Digit Ratio, John T. Manning posits that relative lengths of the second and fourth digits in humans (2D:4D ratio) does provide such a window into hormone- and sex-related traits.

It has been known for more than a century that men and women tend to differ in the relative lengths of their index (2D) and ring (4D) fingers, which upon casual observation seem fairly symmetrical. Men on average have fourth digits longer than their second digits, while women typically have the opposite. Digit ratios are unique in that they are fixed before birth, while other sexually dimorphic variables are fixed after puberty, and the same genes that control for finger length also control the development of the sex organs. The 2D:4D ratio is the only prenatal sexually dimorphic trait that measurably explains conditions linking testosterone, estrogen, and human development; the study of the ratio broadens our view of human ability, talent, behavior, disposition, health, and fertility. In this book, Manning presents evidence for how 2D:4D correlates with traits ranging from sperm counts, family size, musical genius, and sporting prowess, to autism, depression, homosexuality, heart attacks, and breast cancer, traits that are all linked with early exposure to sex hormones.

 

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Contents

V
xvii
VI
22
VII
39
IX
51
XI
60
XIII
74
XIV
98
XVI
113
XVII
124
XIX
139
XX
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XXI
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Page 153 - Rodriguez-Sierra, JF (1989). Neuroendocrine responses to exogenous estrogen: No differences between heterosexual and homosexual men.
Page 157 - Health inequalities among British civil servants: the Whitehall II study, Lancet 337:1387-1393.
Page 156 - A masculinizing effect on the auditory systems of human females having male co-twins. Proc Natl Acad Sci USA 90:11900-11904.
Page 153 - Relationships of serum lipoproteins and apoproteins to sex hormones and to the binding capacity of sex hormone binding globulin in healthy Finnish men.
Page 151 - Garn, SM, AR Burdi, WJ Babler and S. Stinson 1975 "Early Prenatal Attainment of Adult Metacarpal-Phalangeal Rankings and Proportions.
Page 157 - Evolution of Human Music through Sexual Selection." in The Origins of Music, eds..

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About the author (2002)

Manning is a senior lecturer in biological sciences at the University of Liverpool, U.K., and a founding member of the Rutgers University Jamaican Fluctuating Asymmetry Project.

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