I gather from the review that Clark’s argument hinges on a change in behavioral attitudes and the widespread adoption of “capitalist values” (or at least the values and attitudes necessary for a capitalist economy). The novelty in Clark’s work, apart from the considerable amount of new source material he has uncovered, is the part of his argument that suggests that the values necessary for capitalism could have been transmitted genetically.
For thousands of years, most people on earth lived in abject poverty, first as hunters and gatherers, then as peasants or laborers. But with the Industrial Revolution, some societies traded this ancient poverty for amazing affluence.
Historians and economists have long struggled to understand how this transition occurred and why it took place only in some countries. A scholar who has spent the last 20 years scanning medieval English archives has now emerged with startling answers for both questions.
Gregory Clark, an economic historian at the University of California, Davis, believes that the Industrial Revolution — the surge in economic growth that occurred first in England around 1800 — occurred because of a change in the nature of the human population. The change was one in which people gradually developed the strange new behaviors required to make a modern economy work. The middle-class values of nonviolence, literacy, long working hours and a willingness to save emerged only recently in human history, Dr. Clark argues.
Because they grew more common in the centuries before 1800, whether by cultural transmission or evolutionary adaptation, the English population at last became productive enough to escape from poverty, followed quickly by other countries with the same long agrarian past.
Dr. Clark’s ideas have been circulating in articles and manuscripts for several years and are to be published as a book next month, ‘A Farewell to Alms’ (Princeton University Press). Economic historians have high praise for his thesis, though many disagree with parts of it.
The final part of the review quotes several other prominent economic historians, including Kenneth Pomerantz, whose book The Great Divergence I am currently reading, and Robert P. Brenner, whose series of articles in Past and Present from the late 1970s and 1980s are basically “required reading” for any British or European historian. Both Pomerantz and Brenner are somewhat critical of Clark’s argument.
Dr. Clark says the middle-class values needed for productivity could have been transmitted either culturally or genetically. But in some passages, he seems to lean toward evolution as the explanation. “Through the long agrarian passage leading up to the Industrial Revolution, man was becoming biologically more adapted to the modern economic world,” he writes. And, “The triumph of capitalism in the modern world thus may lie as much in our genes as in ideology or rationality.”
What was being inherited, in his view, was not greater intelligence — being a hunter in a foraging society requires considerably greater skill than the repetitive actions of an agricultural laborer. Rather, it was “a repertoire of skills and dispositions that were very different from those of the pre-agrarian world.”
Reaction to Dr. Clark’s thesis from other economic historians seems largely favorable, although few agree with all of it, and many are skeptical of the most novel part, his suggestion that evolutionary change is a factor to be considered in history.
Historians used to accept changes in people’s behavior as an explanation for economic events, like Max Weber’s thesis linking the rise of capitalism with Protestantism. But most have now swung to the economists’ view that all people are alike and will respond in the same way to the same incentives. Hence they seek to explain events like the Industrial Revolution in terms of changes in institutions, not people.
Dr. Clark’s view is that institutions and incentives have been much the same all along and explain very little, which is why there is so little agreement on the causes of the Industrial Revolution. In saying the answer lies in people’s behavior, he is asking his fellow economic historians to revert to a type of explanation they had mostly abandoned and in addition is evoking an idea that historians seldom consider as an explanatory variable, that of evolution.
Most historians have assumed that evolutionary change is too gradual to have affected human populations in the historical period. But geneticists, with information from the human genome now at their disposal, have begun to detect ever more recent instances of human evolutionary change like the spread of lactose tolerance in cattle-raising people of northern Europe just 5,000 years ago. A study in the current American Journal of Human Genetics finds evidence of natural selection at work in the population of Puerto Rico since 1513. So historians are likely to be more enthusiastic about the medieval economic data and elaborate time series that Dr. Clark has reconstructed than about his suggestion that people adapted to the Malthusian constraints of an agrarian society.
“He deserves kudos for assembling all this data,” said Dr. Hoffman, the Caltech historian, “but I don’t agree with his underlying argument.”
The decline in English interest rates, for example, could have been caused by the state’s providing better domestic security and enforcing property rights, Dr. Hoffman said, not by a change in people’s willingness to save, as Dr. Clark asserts.
The natural-selection part of Dr. Clark’s argument “is significantly weaker, and maybe just not necessary, if you can trace the changes in the institutions,” said Kenneth L. Pomeranz, a historian at the University of California, Irvine. In a recent book, “The Great Divergence,” Dr. Pomeranz argues that tapping new sources of energy like coal and bringing new land into cultivation, as in the North American colonies, were the productivity advances that pushed the old agrarian economies out of their Malthusian constraints.
Robert P. Brenner, a historian at the University of California, Los Angeles, said although there was no satisfactory explanation at present for why economic growth took off in Europe around 1800, he believed that institutional explanations would provide the answer and that Dr. Clark’s idea of genes for capitalist behavior was “quite a speculative leap.”
Dr. Bowles, the Santa Fe economist, said he was “not averse to the idea” that genetic transmission of capitalist values is important, but that the evidence for it was not yet there. “It’s just that we don’t have any idea what it is, and everything we look at ends up being awfully small,” he said. Tests of most social behaviors show they are very weakly heritable.
He also took issue with Dr. Clark’s suggestion that the unwillingness to postpone consumption, called time preference by economists, had changed in people over the centuries. “If I were as poor as the people who take out payday loans, I might also have a high time preference,” he said.
Dr. Clark said he set out to write his book 12 years ago on discovering that his undergraduates knew nothing about the history of Europe. His colleagues have been surprised by its conclusions but also interested in them, he said.
“The actual data underlying this stuff is hard to dispute,” Dr. Clark said. “When people see the logic, they say ‘I don’t necessarily believe it, but it’s hard to dismiss.’ ”
. When I read this book a few years ago I was impressed by the way that Brown tried to pinpoint by several different measures when Christianity peaked and began to decline in Britain. Brown gave quite a bit of quantitative evidence in the form of Sunday School attendance and other measures of religiosity in order to precisely answer the question. Although any attempt to measure something that is ultimately a matter of personal sentiment and conscience (Sunday School attendance, for instance, just because people were attending more, does that mean they were there because they were religious or for other reasons) is going to be somewhat difficult, I appreciated the way that Brown assembled statistics. 
Nevertheless, reading about Professor Jenkins’ experience made me think about the entire concept of pimping a course.