A statement concerning the physical composition of humans was once made by Plato, one of the most renowned and celebrated cogitators of recorded history. The great philosopher and educator observed that, “humans are featherless bipeds”. In an empirical sense, this statement is completely true. Humans have two legs and lack feathers, so too do primates and macropods such as Kangaroos. While Plato’s statement is an accurate description of humans, it is neither exhaustive nor unique. There are many other species that share bipedalism with humans. The fact that humans are bipedal and featherless means that Plato’s statement is a necessary condition for being human. That humans share this characteristic with other species indicates that the condition is not solely sufficient for determining humanity.