From this NYT Book review discussing "The Rational Optimist," by Matt Ridley:

"As they specialized and exchanged, humans learned how to domesticate crops and animals and sell food to passing merchants. Traders congregated in the first cities and built ships that spread goods and ideas around the world.

The Phoenician merchants who sailed the Mediterranean were denounced by Hebrew prophets like Isaiah and Greek intellectuals like Homer. But trading networks enabled the ancient Greeks to develop their alphabet, mathematics and science, and later fostered innovation in the trading hubs of the Roman Empire, India, China, Arabia, Renaissance Italy and other European capitals.

Rulers like to take credit for the advances during their reigns, and scientists like to see their theories as the source of technological progress. But Dr. Ridley argues that they've both got it backward: traders' wealth builds empires, and entrepreneurial tinkerers are more likely to inspire scientists than vice versa. From Stone Age seashells to the steam engine to the personal computer, innovation has mostly been a bottom-up process.

"Forget wars, religions, famines and poems for the moment," Dr. Ridley writes. "This is history's greatest theme: the metastasis of exchange, specialization and the invention it has called forth, the 'creation' of time."

You can appreciate the timesaving benefits through a measure devised by the economist William D. Nordhaus: how long it takes the average worker to pay for an hour of reading light. In ancient Babylon, it took more than 50 hours to pay for that light from a sesame-oil lamp. In 1800, it took more than six hours of work to pay for it from a tallow candle. Today, thanks to the countless specialists producing electricity and compact fluorescent bulbs, it takes less than a second. That technological progress, though, was sporadic. Innovation would flourish in one trading hub for a while but then stagnate, sometimes because of external predators — roving pirates, invading barbarians — but more often because of internal parasites, as Dr. Ridley writes:

"Empires bought stability at the price of creating a parasitic court; monotheistic religions bought social cohesion at the expense of a parasitic priestly class; nationalism bought power at the expense of a parasitic military; socialism bought equality at the price of a parasitic bureaucracy; capitalism bought efficiency at the price of parasitic financiers."
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