This paper provides a qualified defense of Martin Heidegger’s controversial assertion that humans and animals differ in kind, not just degree. He has good reasons to defend the human difference, and his thesis is compatible with the evolution of humans from other animals. He argues that the human environment is the world of meaning and truth, an environment which peculiarly makes possible truthful activities such as biology. But the ability to be open to truth cannot be a feature of human (...) biology, without making such pursuits as biology, mathematics, and philosophy a biological function of a certain species, homo sapiens. To deny the human difference amounts to species relativism which leaves the normativity of truth unexplained. To reconcile the human evolutionary heritage and the uniquely human openness to meaning and truth, the paper amplifies a distinction occasionally made by Heidegger between condition and cause. (shrink)