The Doctor in “Listen”

Listen! Question: Why do we talk out loud when we know we're alone? Conjecture: because we know we are not. Evolution perfects survival skills. There are perfect hunters. There is perfect defense. Question: Why is there no such thing as perfect hiding? Answer: How would you know? Logically, if evolution were to perfect a creature whose primary skill were to hide from view, how could you know it existed? It could be with us every second and we would never know. How would you detect it? Even sense it? Except in those moments when, for no clear reason, you choose to speak aloud. What would such a creature want? What would it do? Well?! [yelling] What would you do?