I think the feeling that we choose our actions, is actually not so clear a feeling. If you pay attention to how you actually make decisions, even simple ones, it is difficult to see where a "conscious being" played any part. You don't think your thoughts before you think them. They just arise out of the darkness of our subconscious minds and pop into our consciousness. We didn't consciously make them, or control them -- they just showed up. It seems that whatever we call consciousness, it is more of a leach that takes credit for what the subconscious animal does. To me, at best, the conscious mind is a journaler of thought, and perhaps is an offshoot of memory and our association engine.

>* You don't think your thoughts before you think them. They just arise out of the darkness of our subconscious minds and pop into our consciousness. We didn't consciously make them, or control them -- they just showed up. It seems that whatever we call consciousness, it is more of a leach that takes credit for what the subconscious animal does. *

Neuroscience actually confirms this :-) Brain scans show that conscious thoughts are reflections of subconscious processes doing all the work, AND that the rational mind is very good at creating post-hoc rationalizations for explaining "reasons" of why you arrived to the decisions you took. Most of what we call "reasoning" is about creating narratives to save our self-esteem.

If consciousness is an epiphenomenon, what was it that led Newton to create Calculus (for example). It's not clear to me how such a thing could come about via instinct.

It could just be the right kind of inputs. And I don't mean just education and such, but literally every perception Newton ever had over the course of his life, plus any genetic factors.