During tactile interaction, skin deformation drives the widespread activation of tactile afferents distributed across the fingertip. Yet the full spatial extent and evolution of these deformations remain largely unquantified. Using high-resolution 3D imaging, we reconstructed the complete volar surface of the fingertip under progressive tangential loadings typical of object manipulation. We show that much of the deformation occurs in the out-of-contact regions, accounting for approximately 70% of the total deformation energy. This deformation consistently initiates in the peripheral zones and smoothly propagates inward as partial slip develops. Tangential loading also induces pronounced directional asymmetries and local curvature changes, reflecting both surface and bulk tissue deformation. Furthermore, we observe localized strain patterns consistent with skin wrinkling across all participants, with individual variations in intensity and location driven by distinct frictional and biomechanical properties. This dataset provides a strong foundation for developing highly accurate biomechanical models and for linking fingertip mechanics to tactile neural encoding.
Adaptation to free-living drives loss of beneficial endosymbiosis through metabolic trade-offs
Symbioses are widespread (1) and underpin the function of diverse ecosystems (2-6), but their evolutionary stability is challenging to explain (7,8). Fitness trade-offs between con-trasting