biostudies-literatureUnknown7(7)Shaw CNUnique compared with recent and prehistoric Homo sapiens, Neandertal humeri are characterised by a pronounced right-dominant bilateral strength asymmetry and an anteroposteriorly strengthened diaphyseal shape. Remodeling in response to asymmetric forces imposed during regular underhanded spear thrusting is the most influential explanatory hypothesis. The core tenet of the "Spear Thrusting Hypothesis", that underhand thrusting requires greater muscle activity on the right side of the body compared to the left, remains untested. It is unclear whether alternative subsistence behaviours, such as hide processing, might better explain this morphology. To test this, electromyography was used to measure muscle activity at the primary movers of the humerus (pectoralis major (PM), anterior (AD) and PloS onee40349https://www.ebi.ac.uk/biostudies/studies/S-EPMC3399840biostudies-literatureNeandertal humeri may reflect adaptation to scraping tasks, but not spear thrusting.PMC3399840Gottschall JSStock JTShaw CNPetraglia MDHofmann CLfalseNeandertal humeri may reflect adaptation to scraping tasks, but not spear thrusting.Unique compared with recent and prehistoric Homo sapiens, Neandertal humeri are characterised by a pronounced right-dominant bilateral strength asymmetry and an anteroposteriorly strengthened diaphyseal shape. Remodeling in response to asymmetric forces imposed during regular underhanded spear thrusting is the most influential explanatory hypothesis. The core tenet of the "Spear Thrusting Hypothesis", that underhand thrusting requires greater muscle activity on the right side of the body compared to the left, remains untested. It is unclear whether alternative subsistence behaviours, such as hide processing, might better explain this morphology. To test this, electromyography was used to measure muscle activity at the primary movers of the humerus (pectoralis major (PM), anterior (AD) and 2012-01-01T00:00:00Z20122025-05-29T22:27:46.357Z2025-05-29T22:27:46.357ZS-EPMC33998402281574210.1371/journal.pone.0040349