I've read a book named "Cheating Time : Science, Sex and Aging" by Roger Gosden. There he mentions that natural selection occurs as a process of mutations. So suppose we have some individuals of a species that have suddenly got some mutation which gives them better chance of survival in a given environment then they survive better and that's how it works. So my question is, is it all that random? Because we usually say that when environmental conditions change the species that adapts quickly survives and the others don't. This sounds like that it is an active process that is a product of the species' efforts to survive. But Roger Gosden's description gives it a passive nature. Things occur on their own. I fit favours one well and good, the others die. Please clear this point. thank You.