[It's an interesting enough subject that he turns around, more to study Walt in depth than out of unbalancing, unfocused surprise. His gaze doesn't stray - it's challenging Walt to prove he's as smart as he hopes, but in a way that's academic and not hormonal alpha-male nonsense.

He holds himself above such animal instinct. But he's smart enough to realize it's presence in humans as a whole.]

I suppose that's true.

[The hidden implication is he agrees with what Walt's saying.]

Now. Many discoveries come about as a result of self-experimentation. The discovery of metabolism, for instance. Single-subject scientific experimentation has a long and well-documented history going back to the ancient eras. There's always a means and a way.