Meeting Abstract
Bipedal locomotion has evolved numerous times among mammals and birds. Hopping is generally limited to, or in the case of marsupials at least originated in, relatively small animals. Hopping mammals tend to be fast and hop over considerable distances; in contrast, birds that hop on the ground tend often do so intermittently, with a characteristic start-stop-start progress. If the cost of activating muscle dominates, and muscle must be activated fundamentally to provide the work and power of locomotion, simple scaling laws provide considerable insight. The cost of steady hopping approaches that of running – both dominated by issues of power rather than work – at small size scales and high speeds. Slow hopping, especially among large animals, is predicted to be especially costly due to the relative dominance of vertical work requirements. At small sizes (leg lengths less than 0.2m), a single thrush-like hop stride is predicted to be less costly than a single running stride (starting and finishing stationary). Hopping may confer a range of advantages over running or quadrupedal gaits; differential scaling of work and power provides an account for why smaller, faster animals are less energetically precluded from hopping, and hopping can be more economical for short distances.
