"As a species, over short distances, we are hopeless runners. We might be able to go a long way but what use is that if we can’t catch anything? The truth is that we never could if it weren’t for several factors that make us identifiably human. And it is our ability to perspire which renders them all effective. So we may have perfect bodies for distance running, but those features that enable us to move so effectively are useless without correct temperature control."