This became known as the "Malthusian trap." That Western population grew despite the vices of industrialisation was one of the main arguments why McKeown put so much emphasis on one of the few virtues of early industrialisation: the country was able to produce and provide more and better food for the people. Flinn (1971) already found for the pre-industrial 18th century that mortality crises were less than in the 17th century, and explained that by reduced fluctuations in food prices and fewer and less severe periods of famine by increased food imports during periods of failed crops, and by an agricultural transition from monoculture (grain) to more diverse products (rice, maize and buckwheat in the south, and potatoes in the north). Industrialization further improved the efficiency of food culturing, processing and transport. Back in 1976, McKeown was criticised for failing to convince "‘that an improvement in per capita nutrition actually did occur’". McKeown was thereby criticised for using sloppy methodology; McKeown himself was well aware that his theory was hampered by insufficiency of then available data, particularly data from the early industrialisation during the 18th century, and he confided that he had deduced some of his conclusions ‘on the principle enunciated by Sherlock Holmes: "When you have eliminated the impossible, whatever remains, however improbable, must be the truth." [McKeown, 1988; pages 9–10]  Since McKeown first proposed his thesis, several historians of economics have gathered supportive evidence for the McKeown thesis. Particularly the valuable work on the "technophysio evolution" by Nobel prize laureate economist Robert Fogel and collaborators has contributed to the acceptance of McKeown's thesis. As summarised by Angus Deaton (2013, pp 91–92):  "Nutrition was clearly part of the story of early mortality decline. ... With the beginnings of the agricultural revolution, the [Malthusian] trap began to fall apart. Per capita incomes began to grow and, perhaps for the first time in history, there was the possibility of steadily improving nutrition. Better nutrition enabled people to grow bigger and stronger, which further enabled productivity to increase. ... Taller, bigger people lived longer, and better nourished children were less likely to die and better able to ward of disease." Knibbe (2007) combined physiological indicators of health with economical data and discovered a direct relation between food intake, food price and health in the Netherlands of the 19th century; he for instance described a consistent relation between caloric intake and body length of Dutch conscripts between 1807 and the late 19th century (see Figure).