Human hand-walkers: five siblings who never stood up

Abstract

Human beings begin life as quadrupeds, crawling on all fours, but none has ever been known to retain this gait and develop it into a proficient replacement for adult bipedality. We report the case of a family in which five siblings, who suffer from a rare form of cerebellar ataxia, are still quadrupeds as adults - walking and running on their feet and wrists. We describe the remarkable features of this gait, discuss how it has developed in the members of this family, and consider whether a similar gait may have been used by human ancestors.