Which chicken found it harder to cross the road? By Felipe Brando Cadavid It has been well established that there is a clear relationship between body size/mass and the metabolic cost of locomotion, generally larger animals are more energy efficient than smaller animals as large animals tend to have longer legs that move with fewer strides which also require fewer muscle contractions. This generalization seems to hold true for all animals all the way from nimble insects to large megafauna like elephants, between different species the assumption holds but what about within a species? Does it mean that larger members of a species will have a lower metabolic cost? A study conducted on one our most well-known animal minions, the chicken, has helped us shed some light on the metabolic costs of locomotion within a species and has produced some surprising results. The study compared chickens of different breeds that were anatomically proportional but disparate in size, the...