In 1983, American anthropologist Eric B. Ross put forward arguments based on a detailed study of Scottish agricultural history, and asserted the value of cultural materialism rooted in evolutionary anthropology for studying dietary customs, thus avoiding explanations based on "relatively esoteric" beliefs. Because of deforestation, a loss of beech mast and acorns for feeding pigs occurred, and potatoes were not produced in sufficient quantity to offer a useful alternative until the late 18th century. Throughout this gap in pork consumption by the general population, many of the Scottish upper classes continued to eat the meat. He summed up: