Is There a Borderline Case Between Animals and Humans?

In Aristotle, there is some discussion of borderline cases between animals and humans. The particular species that they discussed was pygmies. And the discussion centered actually on their ability to use reason. I see, so your membership in the species of humanity isn't really decided by what you in fact can do,. but rather just by being a member of the species is already enough to prove that you have an immortal intellectual soul. You have no one ever sees you using it, and in fact, even if you never use it. Imbrasably yes.