Yes, One PERSON Can

Check out Varifrank's excellent post on the question, can one man make a difference? I'm quite sure he means one person, although the people he lists as examples are indeed men. He links to my pick for biggest contribution by a single person, Norman Borlaug, who you can (and should) read about here. Borlaug was brought to my attention by Penn and Teller's show Bullshit, which is one of the best uses for television I've ever seen.