In Nature, successful reproduction is all. And nothing says success quite like 8 billion individuals, even if they are fat and slow. : )
who cares if we are fat and slow? If you're the baddest most highly advanced species on the planet you don't have to be fast and quick to catch food. For crying out loud, we are so powerful now we can even change the weather!
Indeed. Nature doesn't care about our quality of life, she only respects reproductive success. Make it to reproductive age and procreate, by any means necessary, and she's satisfied. Not advocating the merely quantitative for Man, but it seems there's no reason to doubt Darwin, yet. In case anyone finds this direction depressing, take cheer and consider this: you will be dead (and utterly forgotten) very soon in historical terms, and you will miss everything, absolutely everything that follows for the remaining age of the universe! : )
talk about charts, the most impressive chart I ever saw was in Biology 101. It charted the dominance of species. About 6 million years ago there was a huge spike. That was the dinosaurs. And about 6 million years later there is a huge spike which dwarfs the dinosaur spike, and that is the spike we are in now when humans are just about going off the chart. They all get leveled back to the mean.