Our belief in progress, the idea that everything will go on improving, is strangely recent. For a start, our ancestors would have been surprised to learn that we thought we could see into the future at all. Their cultures were built on the reality that no one can.

But they’d have been even more surprised to discover that we believed life would get better. They thought everything had declined since a Golden Age, when all was plenty and people lived in harmony with nature and each other.

The Ancient Greeks and Romans believed we were shrinking physically, and Plato came up with the idea of breeding supermen to reverse this trend. Unlike his near contemporary, Confucius, who more modestly thought we could improve the way we were governed, Plato believed we could not only improve society but improve ourselves.

This idea didn’t really grow teeth until we began to understand the mechanics of breeding, during the Enlightenment. Darwin was careful to call his book the Descent on Man, not the ascent. But believers in eugenics willfully misinterpreted his theory of evolution by means of the survival of the fittest, which meant the most suited not the strongest. This resulted in the mass extermination of those who didn’t fit a predetermined notion of what a better human should be.