Unlike the dinosaurs, we have, in effect, become active agents in changing our destiny. A giant meteor wiped out much of life on earth 65 million years ago because the dinosaurs didn't collectively create a missile shield to deflect the meteor. Humans, on the other hand, with our orbiting telescopes and space probes, and our growing awareness of the threat from space, can track large foreign objects coming from millions of miles away, and are talking about collectively deflecting those that could do us harm.