Handgrip Strength as a Darwinian Fitness Indicator in Men

Authors:
Andrew C. Gallup and Bernhard Fink
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Handgrip strength (HGS) is a robust measure of overall muscular strength and function, and has long been predictive of a multitude of health factors and physical outcomes for both men and women. The fact that HGS represents such a ubiquitous measure of health and vitality may reflect the significance of this trait during human evolution. This trait is also highly sexually dimorphic due to influences of androgenic hormones and fat-free body mass, suggesting that it has been further elaborated through sexual selection. Consistent with this view, research within evolutionary psychology and related fields has documented distinct relationships between HGS and measures of social and sexual behavior, especially in men. Here, we review studies across different societies and cultural contexts showing that male HGS predicts measures of aggression and social dominance, perceived formidability, male-typical body morphology and movement, courtship display, physical attractiveness, and sexual behavior and reproductive fitness. These findings underscore the value of including HGS as an independent measure within studies examining human sexual selection, and corroborate existing research suggesting that specific features of physical strength have and continue to be under positive directional selection in men.

Handgrip Strength as a Fitness Indicator in MenThe marked sexual dimorphism in overall HGS, combined with the distinct genetic and developmental factors influencing men and women, suggests that during human evolutionary history specific features of upper-body muscularity were further elaborated among males through sexual selection. Increased physical strength would have undoubtedly been favored within contexts of direct male–male competition and fighting (Sell et al., 2009), protection from predators (Sell et al., 2012), hunting (Apicella, 2014), and tool use and manufacture (Young, 2003). Arguably, HGS in particular, rather than other features of upper-body muscularity, would have had tremendous importance within these contexts. In regards to fighting, HGS alone is a robust predictor of ability and outcomes. For example, the correlation between HGS and ranking among amateur middleweight boxers is 0.87 (Guidetti et al., 2002). In addition, forearm strength is particularly important for traditional forms of hunting (Smith et al., 2017). Furthermore, tool use and manufacture has likely played a direct role in shaping both precision and powerful gripping during human evolutionary history (Young, 2003). Due to the vital importance of this trait within the ancestral environment, cues of upper-body muscularity and formidability seem to be important features of female mate choice among modern humans as they account for ∼70% of the variance in male bodily attractiveness (Sell et al., 2017). Thus, HGS has likely been under directional selection in men as it relates to reproductive competition.
Consistent with the sex-specific role of HGS within contexts of social and sexual competition, Gallup et al. (2007) found that HGS predicted self-reported levels of aggression, male-typical body morphology, and sexual behavior in men, while none of the variables examined were correlated with HGS in a comparable sample of women. Here, we review the latest literature to investigate the extent to which these initial findings have been replicated and extended. We focused on peer-reviewed articles in evolutionary psychology and related fields that explicitly examined relationships between HGS and measures of inter- and intra-sexual selection. Although a growing number of studies have included HGS within composite measures of upper-body strength (e.g., Sell et al., 2009; Lukaszewski and Roney, 2011; Smith et al., 2017), many fail to report on the specific connection of HGS to the dependent measures. However, in cases where HGS is parceled out of these composite measures we do report the documented effects. Table ​Table11 presents the findings over the last decade specifically linking HGS to measures of intra- and inter-sexual selection and reproductive fitness.


Click link for full article
 www.ncbi.nlm.nih.gov/pmc/articles/PMC5898311/#!po=0.961538
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