The Rational Optimist: How Prosperity Evolves

by Matt Ridley

Bizarre as this may sound, in evolutionary terms it is quite normal. Most species do not change their habits during their few million years on earth or alter their lifestyle much in different parts of their range. Natural selection is a conservative force. It spends more of its time keeping species the same than changing them. Only towards the edge of its range, on an isolated island, or in a remote valley or on a lonely hill top, does natural selection occasionally cause part of a species to morph into something different. That different sport sometimes then spreads to conquer a broader ecological empire, perhaps even returning to replace the ancestral species – to topple the dynasty from which it sprang. There is constant ferment of change within the species’ genes as it adapts to its parasites and they to it. But there is little progressive alteration of the organism. Evolutionary change happens largely by the replacement of species by daughter species, not by the changing of habits in species. What is surprising about the human story is not the mind-bogglingly tedious stasis of the Acheulean hand axe, but that the stasis came to an end.