There is a real tendency for the navel-gazers and hand-wringers in society to constantly bemoan human behavior and overplay its potential effect on the environment. Species and, particularly, societies rise and fall; they have done so since the beginning of our recorded history; and, through a handful of massive extinction events over geological time, ninety-eight-plus percent of all species that ever existed on Earth, are gone -- well before we ever left the trees; walked upright; or discovered fire. We're rank amateurs in that scheme of things.
Then, we have the eternal check and balance of disease. Coincidentally, I am currently reading a great book on malaria and how it altered the course of history; how its spread affected local cultures -- destroying some completely -- and eventually gave rise to the African slave trade -- largely due to the fact that those peoples were far more resistant to malaria's more virulent form, than were the indigenous slaves here, who were decimated by malaria in the earliest colonies. As an aside, Africans were also three times the value of any European indentured servant (who were plentiful at that time), for that very same reason.
Fortunes of individuals and countries rose and fell; and Scotland eventually even lost its independence from England, largely due to a disease-carrying protozoan in the gut of a mosquito, half a world away. They effectively went bankrupt, attempting to fund New Caledonia, a colony on the Darién Coast of Panama, wiped out by the disease; and were absorbed by their neighbors to the South. The plan had been to build a road across the isthmus to open trade.
We now have new antibiotic-resistant bacteria; viruses; retroviruses; hemorrhagic fevers by the handful; prions; and the new-found ability to be anywhere on the globe, spreading disease within twenty-four hours. Malaria has been with us 500,000 years; yet our treatments are still primitive at best; and the disease is rampant.
Regardless of any medical progress, we'll be kept in check one way or the other -- and a Merry Christmas to all!