Mechanical loading of primate fingers on vertical rock surfaces

Mechanical loading of finger bones (phalanges) can induce angular curvature, which benefits arboreal primates by dissipating forces and economising the recruitment muscles during climbing. The recent discovery extremely curved phalanges in a hominin, Homo naledi, is puzzling, for it suggests life an milieu, or, alternatively, habitual climbing on vertical rock surfaces. importance walls attested several populations baboons, one uses 7-m surface to enter exit Dronkvlei Cave, De Hoop Nature Reserve, South Africa. This attractive model estimating probability extreme mechanical rock-climbing primates. Here we use three-dimensional photogrammetry show that 82–91% climbable would generate high flexor tendon pulley system severely load baboons H. naledi. If such proportions are representative surfaces elsewhere, may be sufficient stress-mitigating curvature primates.Significance: We present first photogrammetric analysis climbed non-human primate, chacma baboon (Papio ursinus). Our results large proportion wall compel crimp slope hand positions – grips could explain extraordinary phalangeal expressed Middle Pleistocene