The triumph of capitalism in the modern world thus may lie as much in our genes as in ideology or rationality.
Clark goes on to explain that wealthy businessmen were more likely to have children and thus pass on their business friendly genes to their children. This includes a proclivity towards working and saving.
In short, Clark is saying that greater risk aversion won the evolutionary battle and produced capitalism
The problem is that this is contrary to the notion that capitalism favors risk takers. Clark notes that interest rates fell and that work hours rose. Both I would guess are the result of a less equal distribution of wealth in and of itself. A negative income effect on the workers would lead them to work more.
That is if taxes or rent on your land gets very high, you simply have to work more to support your family. In addition, high rents produce income for the land owners which is far in excess of subsistence and therefore allows for lending.
I would ask the question – was landownership becoming more concentrated as England approached 1800? Even if the number of landowner stayed concentrated or rose, did the landowner to population ratio decline? This seems are more parsimonious explanation.