What I am talking about is philosophical materialism, which says that there is no such thing as the "mental." This is the real reason why there is so much objection to the theory of evolution: because if there is no such thing as mentality then of course there can be no such thing as free will, because what is done physically is not free. It is an automatic reaction, like eye-blinking.
In that case, life is meaningless. We are nothing but robots.
If one accepts the reality of mentality, then it is hard to explain how that could evolve. Mentality from physicality?