Why Spiderman can't exist: Geckos are 'size limit' for sticking to walls

(University of Cambridge) Latest research reveals why geckos are the largest animals able to scale smooth vertical walls -- even larger climbers would require unmanageably large sticky footpads. Scientists estimate that a human would need adhesive pads covering 40 percent of their body surface in order to walk up a wall like Spiderman, and believe their insights have implications for the feasibility of large-scale, gecko-like adhesives.