Speculative reasons evolution would be against free will.

Experimentation proves that humans cannot make random decisions. More often than not, humans form patterns of most difference than random patterns. When asked to scatter randomly in a room, people will fill out to positions but will not, for example, all move to one corner or another act of true randomness.

Evolution would favor a predetermined pattern filling most options than true randomness. Teenage rebellion is an example of this, seeming free will, that is actually determined difference. Randomness would say we could be in a world with 100% the population freely choosing to be carpenters, predetermined choosing of patterns of difference gives us a world where we are all different -- and the belief we think we chose that.