From Louise Leakey‘s TED talk about Humanities Origins:

Who are we? We are certainly an agressive, polluting, wasteful species, with a few nice things thrown in perhaps. For the most part we are not particularly pleasant at all. We have a much bigger brain than our ape anscestors. Is this a good evolutionary adaptation. Or is it going to lead us to be the shortest lived hominid species on planet earth?

Although she it not a terribly good speaker, I found her message powerful. Because of her research (and that of her family’s for two previous generations) she has a very long-term perspective on our planet.