Another issue is that when labor is cheap and plentiful one is less likely to invest in technology. There is a thesis that the Black Plague broke Europe out of

Another issue is that when labor is cheap and plentiful one is less likely to invest in technology. There is a thesis that the Black Plague broke Europe out of a 'Matlthusian Deadlock' that size of the population made labor cheap enough that investing in agricultural technology had low returns, at the same time that same size led to everyone constantly being on the razors edge of famine.