A related question is – what is the source of the brocha that Ashkenazim got to grow like fish? Besides Torah scholarship, a possible answer is – beans. New agricultural methods introduced in Northern Europe in middle ages involved cross-growing beans and grain. Population was usually limited by amount of available protein that, in turn, was limited by amount of livestock that was limited by multiple factors – amount of grain, fields, labor … Beans introduced additional protein that lead to growth of population in Northern Europe comparative to Mediterranean. It also lead us to a kitniyos issue on Pesach, but it seems to be a small price to pay.
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