Elsevier

Biological Psychology

Volume 68, Issue 3, March 2005, Pages 215-222
Biological Psychology

Finger length ratio (2D:4D) correlates with physical aggression in men but not in women

https://doi.org/10.1016/j.biopsycho.2004.05.001Get rights and content

Abstract

Finger length ratio (2D:4D) is a sexually dimorphic trait. Men have relatively shorter second digits (index fingers) than fourth digits (ring fingers). Smaller, more masculine, digit ratios are thought to be associated with either higher prenatal testosterone levels or greater sensitivity to androgens, or both. Men with more masculine finger ratios are perceived as being more masculine and dominant by female observers, and tend to perform better in a number of physical sports. We hypothesized that digit ratio would correlate with propensity to engage in aggressive behavior. We examined the relationship between trait aggression, assayed using a questionnaire, and finger length ratio in both men and women. Men with lower, more masculine, finger length ratios had higher trait physical aggression scores (rpartial = −0.21, N = 134, P = 0.028). We found no correlation between finger length ratio and any form of aggression in females. These results are consistent with the hypothesis that testosterone has an organizational effect on adult physical aggression in men.

Section snippets

Finger length ratio (2D:4D) correlates with physical aggression in men but not in women

Finger length ratio (2D:4D) is a sexually dimorphic trait. The ratio of second digit (index finger) to fourth digit (ring finger) is smaller for males than females in humans, mice, and baboons (Brown et al., 2002b, Manning, 2002a, Manning et al., 2000, McFadden and Bracht, 2003, McFadden and Shubel, 2002, Peters et al., 2002). In zebra finches, the sexual dimorphism in digit ratio is reversed, and males have relatively longer second digits (Burley and Foster, 2004). This reversed foot pattern

Results

Men had smaller finger length ratios than women (Table 1). Hostility, verbal, physical, and total aggression scores showed significant sexual dimorphism, while anger did not.

Anger significantly correlated with the other three sub-scales of aggression (hostility, verbal, and physical aggression) in men (Table 2). Of the other sub-scales, the two instrumental measures of aggression (verbal and physical) were correlated. All scores on the four sub-scales were correlated in women, except in the

Discussion

We found significant sexual dimorphism in physical aggression, verbal aggression and hostility but no difference in anger. Physical aggression was the most sexually dimorphic of the aggression indices (d = 1.05). These results agree with Buss and Perry (1992), who found hostility, verbal, and physical aggression, but not anger to be sexually dimorphic, and trait physical aggression to be most dimorphic (d = 0.89).

We found digit ratio to correlate with physical aggression, but not with

Acknowledgments

Research was funded by an NSERC (Canada) Discovery grant to PLH. We wish to thank Ray Engeszer, Jamie Dyce, Alinda Friedman, Bob Trivers and Paul Vasey for valuable discussion and Walter Espinoza and Tricia Lowrey for assistance in collecting the data. We also thank Christopher Sturdy, and three anonymous reviewers for helpful comments on the manuscript.

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      At the same time, although some research has linked the ratio to sensation seeking (Hampson et al., 2008), meta-studies have neither provided support for this negative association (Voracek, Tran, & Dressler, 2010) nor demonstrated a link between the ratio and female aggression (Bailey & Hurd, 2005; Hönekopp & Watson, 2011). On the other hand, whereas studies have reported weak quantitative effects for aggression, violence, and criminal behaviour (Bailey & Hurd, 2005; Hönekopp & Watson, 2011; Pratt, Turanovic, & Cullen, 2016; Turanovic, Pratt, & Piquero, 2017), the links between 2D:4D and sports performance appear more robust. These latter include such interesting findings as an association between a lower digit ratio and better football (Manning & Taylor, 2001) or rugby performance (Bennett, Manning, Cook, & Kilduff, 2010), greater football aggressiveness (Perciavalle et al., 2013), better defensive playing and more efficient scoring in basketball (Dyer, Short, Short, Manning, & Tomkinson, 2018).

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