It seems, in the grander scheme of things, that we humans live on a rather small planet with limited resources. That fact of life has shaped our evolution.
• In the hunter-gatherer culture of a few tens of centuries ago, the nearly nonexistent technology of the period could support only a few million people.
• We can only go without food, drink, warmth, sanitary facilities, and other necessities for rather short periods of time.
Thus, from the beginning of our evolutionary history, we have been up against the limits of time and resources. It is built into our genes to be careful about both.
Beginning about a million years ago, our forerunners found that stone tools could ameliorate this harsh ...