If I could do it all over again, I would study biology. Some scientists who have influenced me include Stephen Jay Gould, Richard Dawkins, Oliver Sacks and Jane Goodall. Of course, it goes without saying that Charles Darwin is one of my heroes.
Anyway I have included a link to a most fascinating book that I read recently, A New History of Life by Peter D. Ward and Joe Kirschvink. You will never look at the world the same way!