I never believed the theory that the dinosaurs were killed by an asteroid hitting the earth. I hold that, as Darwin would have predicted, the dinosaurs no longer "fit" into the environment which had changed because lizards had grown into dinosaurs that were so large that they had no effective enemies, and so could eat up their entire food supply and then starve to death! So, humans, whose brains are so large that they "hold dominion over the Earth" and, like the dinosaurs, have no effective enemies will, as Malthus predicted, over-populate, and then eat up their entire food supply, etc. But first, I'm afraid, humans will use up all the energy-producing resources, crowd into the remaining temperate zones, fight devastating wars over food, and finally eat up the entire food supply, etc. This will take a while, perhaps millions of years, but it's inevitable. Eventually, we, too, will no longer "fit" into the environment which we, ourselves, LOUSED UP, and we'll become as extinct as dinosaurs.