In the ancient age of hunting and gathering, gathering required care: observing the color of fruit and predicting when it would ripen.
Hunting, on the other hand, required swift movement, guessing which way prey would flee. And because prey fought back, it carried greater risks than gathering.
Hunters did not have much time for logical thought. They needed faster reflexes and had to make decisions in the shortest possible time.
Biological evolution followed the principle of least effort. Animals that lived in caves or the deep sea did not need good eyesight, because there was no light there at all. They used other senses in place of vision; bats, for example, used echolocation.
The "people in the cave" Plato spoke of could see the shadows on the cave wall, but they still needed torchlight.
The human mind also followed the principle of least effort when thinking. This system of "heuristics" was highly effective. Evolutionary biologists casually reasoned in terms of millions of years, and humanity had relied on it to survive throughout that time—far longer than the history of human "civilization."
Yet with enormous changes in productivity and ways of life, this mode of thought adapted to primitive living instead brought certain inconveniences to modern humans.
Babies first put everything they saw into their mouths. This was their earliest way of understanding the world. They did not know whether those things were dangerous, and parents sometimes had to take away things that could harm them.
As they grew a little older, they learned to perceive through their hands, language, and other means. Their cognitive dimensions changed, and their conceptual systems gradually grew richer.
When adults entered a new environment, everything differed from the world they had assumed they knew. Young people were often better able to adjust their cognitive frameworks