"Natural" is not "better". Disease, famine and predation are the enemies of mankind. In order for ecology to mean anything, it must mean striving for an environment that is suitable for human life. It was good environmental policy to eradicate smallpox. It was good environmental policy to eradicate dire wolves. It was good environmental policy to reduce the buffalo herds and devote the Great Plains of North American to food production.
What kind of quality life do you think you (well who knows you might be one of the very few lucky rich) would have when our population really starts to exceed the carrying capacity of the earth?
It can only be a problem if human ingenuity is held in check. Human population exploded in the 20th century, but the carrying capacity of the Earth more than kept pace with it. Famine and pestilence have never been as uncommon as today.
As long as we are permitted to discover and exploit new energy resources, to exploit the machinery of life to improve human health and food production, and to learn how to live well outside the surly bonds of Earth, mankind will not merely live long, but prosper.