*Article* **Get a Grip: Variation in Human Hand Grip Strength and Implications for Human Evolution**

**Ameline Bardo 1,\*, Tracy L. Kivell 1,2, Katie Town 1, Georgina Donati 3, Haiko Ballieux 4, Cosmin Stamate 5, Trudi Edginton 6 and Gillian S. Forrester 7**


**Abstract:** Although hand grip strength is critical to the daily lives of humans and our arboreal grea<sup>t</sup> ape relatives, the human hand has changed in form and function throughout our evolution due to terrestrial bipedalism, tool use, and directional asymmetry (DA) such as handedness. Here we investigate how hand form and function interact in modern humans to gain an insight into our evolutionary past. We measured grip strength in a heterogeneous, cross-sectional sample of human participants (n = 662, 17 to 83 years old) to test the potential effects of age, sex, asymmetry (hand dominance and handedness), hand shape, occupation, and practice of sports and musical instruments that involve the hand(s). We found a significant effect of sex and hand dominance on grip strength, but not of handedness, while hand shape and age had a greater influence on female grip strength. Females were significantly weaker with age, but grip strength in females with large hands was less affected than those with long hands. Frequent engagemen<sup>t</sup> in hand sports significantly increased grip strength in the non-dominant hand in both sexes, while only males showed a significant effect of occupation, indicating different patterns of hand dominance asymmetries and hand function. These results improve our understanding of the link between form and function in both hands and offer an insight into the evolution of human laterality and dexterity.

**Keywords:** power grip strength; directional asymmetry; hand dominance; hand shape; manual activities; human evolution; functional morphology
