Abstract
Changes in hand morphology throughout human evolution have facilitated the use of forceful pad-to-pad precision grips, contributing to the development of fine motor movement and dexterous manipulation typical of modern humans. Today, variation in human hand function may be affected by demographic and/or lifestyle factors, but these remain largely unexplored. We measured pinch grip strength and dexterity in a heterogeneous cross-sectional sample of human participants (n = 556) to test for the potential effects of sex, age, hand asymmetries, hand morphology, and frequently practiced manual activities across the lifespan. We found a significant effect of sex on pinch strength, dexterity, and different directional asymmetries, with the practice of manual musical instruments, significantly increasing female dexterity for both hands. Males and females with wider hands were also stronger, but not more precise, than those with longer hands, while the thumb-index ratio had no effect. Hand dominance asymmetry further had a significant effect on dexterity but not on pinch strength. These results indicate that different patterns of hand asymmetries and hand function are influenced in part by life experiences, improving our understanding of the link between hand form and function and offering a referential context for interpreting the evolution of human dexterity.
Highlights
We further explored if variation in hand shape and thumb-index ratio influence both pinch grip strength and dexterity
Our first prediction that males would have stronger pinch grip strength and females would be more dexterous compared to thetoopposite sex was which iswhich consistent would be more dexterous compared the opposite sexsupported, was supported, is conwith previous
We found no significant influence of manual occupations on either pinch grip strength or dexterity, which was contrary to our prediction
Summary
The hominin fossil record demonstrates that the human hand has undergone morphological and functional changes that distinguish it from other non-human primates (e.g., [1,2,3,4]). Adaptive (or -exaptive) changes such as increased brain asymmetry [5] and a larger thumb-finger ratio are generally associated with enhancements in manual dexterity and fine motor movements, including forceful pad-to-pad precision grips, considered a unique human ability [1,6]. Previous studies have documented variation in pinch grip (a form of precision grip) strength between males and females [11,12,13], but it is not known how differences in hand morphology or frequent engagement in activities that require (forceful) precision grips might influence ones’ manual dexterity. A better understanding of the form-function relationship of the human hand may offer valuable clinical insights (e.g., early identification of hand disorders for preventive treatment) but can inform our understanding of how enhanced dexterity of the human hand evolved
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