The Evolution of Affluence

History tends to make even the most unlikely revolutions seem inevitable. Looking backwards to the 18th century, it's easy to conclude that the Industrial Revolution was bound to happen, that the forward march of modernity was predestined.

But what this fatalistic view of history overlooks is just how unlikely it is that a nomadic band of hunter-gatherers would one day settle in big cities, develop some startling new technologies, and escape the Malthusian trap. Starting in the 18th century, a few select human populations (such as Great Britain) managed to increase their economic productivity to such an extent that the struggle for existence was no longer such a bleak struggle. Gregory Clark, an economic historian at UC Davis, thinks he has figured out the mechanisms underlying this dramatic transformation. His theory is both simple and improbable: the Industrial Revolution was made possible by human evolution. In other words, we evolved the specific behavioral traits that allowed modernity to exist.

For thousands of years, most people on earth lived in abject poverty, first as hunters and gatherers, then as peasants or laborers. But with the Industrial Revolution, some societies traded this ancient poverty for amazing affluence.

Historians and economists have long struggled to understand how this transition occurred and why it took place only in some countries. A scholar who has spent the last 20 years scanning medieval English archives has now emerged with startling answers for both questions.

Gregory Clark, an economic historian at the University of California, Davis, believes that the Industrial Revolution -- the surge in economic growth that occurred first in England around 1800 -- occurred because of a change in the nature of the human population. The change was one in which people gradually developed the strange new behaviors required to make a modern economy work. The middle-class values of nonviolence, literacy, long working hours and a willingness to save emerged only recently in human history, Dr. Clark argues.

Because they grew more common in the centuries before 1800, whether by cultural transmission or evolutionary adaptation, the English population at last became productive enough to escape from poverty, followed quickly by other countries with the same long agrarian past.

Obviously, Clark's thesis directly contradicts the conventional explanation for the Industrial Revolution, which is that a combination of political and economic factors, from mercantilism to the discovery of the New World, led to the Industrial Revolution. Human biology plays no role. Clark's theory also arrives just as scientists are discovering the dramatic extent of recent human evolution. (See, for example, the evolution of lactose tolerance in Norther European populations.)

But I'm still not convinced by Clark's theory (although I do plan on reading his forthcoming book). I think any theory of history that relies on evolutionary changes within a population dramatically underestimates the flexibility and plasticity of the human brain. We are a malleable species. Some of us still live in remote tribes and hunt game while others sit all day in front of a computer, composing sentences. The mind is capable of thriving in both instances precisely because it is so adaptable, because our genes have evolved the talent of massive neural plasticity. I'd wager that it is this invention of cortical plasticity - a rather ancient adaptation - which made the Industrial Revolution possible. All of the other behavioral modifications that Clark cites - the propensity to save, the ability to live in densely populated cities, etc. - were all by-products of this central adaptation, which let us endlessly adapt to our circumstances.