Wondering why one's friends chose to marry the people they did is unprofitable, but recurrent. - John Wyndham

But we had learnt, as had many before us, about the bread-alone factor, one needed more than adequate food.

A species continues to exist by outbreeding the checks that its natural enemies impose on it. That is what gives the illusion of "the balance of nature" belief. Once the natural enemies cease to be a threat its fecundity becomes terrifying. Look what has happened in a generation or two to our own population, largely because a few diseases have been overcome. Find a way of conquering the natural enemies, and the only limiting factor is the food supply.

It's all pretty simple if you don't give a damn who gets hurt in the rush.