1. The ability of cheap slave labor in classical times supposedly discouraged innovation then, whereas high wages or labor scarcity now stimulate the search for technological solutions.
2. Patents and other property laws, protecting ownership rights of inventors, reward innovation in the modern West, while lack of such protection discourages it in modern China.
3. Modern industrial societies provide extensive opportunities for technical training, as medieval Islam did and modern Zaire does not.
4. Modern Capitalist is, and the ancient Roman economy was not, organized way that made it potentially rewarding to invest in capital in technological development.
5. The strong individualism of U.S. society allows successful inventors to keep earnings for themselves, wheres as strong family ties in New Guinea ensure that someone who begins to earn money will be joined by a dozen relatives expecting to move in and be fed and supported.

Guns, Germs, and Steel

The Fates of Human Societies – Jared Diamond

Necessity’s Mother