The Rational Optimist (P.S.)

by Matt Ridley

On the way up the graph, abundant food encourages some people to specialise in something other than growing or catching food, while others produce food for sale not for self-sufficiency. The division of labour increases. But when the food supply becomes tight, near the top of the graph, fewer people will be prepared to sell their food or will have a surplus to sell. They will feed it to their families and make do without the goods they were wont to buy from others. The non-farmers, finding both food and customers for their services harder to come by, will have to give up their jobs and return to growing their own food themselves. So there is a cycle of rising and falling specialisation in human populations. The economist Vernon Smith, in his memoirs, recalls how in the Depression his family moved in the 1930s from Wichita, Kansas, to a farm when his father was laid off as a machinist, because ‘we could at least grow most of our own food and participate in a subsistence economy.’ This return to subsistence happens often in human history.