the morphology of the distal phalanges of human thumbs closely reflects an adaptation for a refined precision grip with pad-to-pad contact. this has traditionally been associated with the advent of stone tool-making. however, the intrinsic hand proportions of australopiths and the resemblance between human hands and the short hands of miocene apes, suggest that human hand proportions are largely plesiomorphic (as found in ancestral species) — in contrast to the derived elongated hand pattern and poorly developed thumb musculature of other extant hominoids.