Colonists appreciated the food preservation aspect of crusty-topped pies, which were often seasoned with "dried fruit, cinnamon, pepper and nutmeg". Their first pies included pies that were based on berries and fruits pointed out to them by the Native North Americans. Pies allowed colonial cooks to use round shallow pans to literally "cut corners" and to create a regional variation of shallow pie. By the late 1700s, cookbooks show a wide range of newly developed sweet pies. Pies became more refined with subsequent waves of immigrants; the Pennsylvania Dutch contributed a more aromatic, spiced, and less-sweet style of pie-making; the French brought the approach of making pie with butter and a range of tart, galette and pâté (forcemeat of meat and fish in dough) recipes. Swedish immigrants in the plains states brought recipes for fish pie and berry pie; Finnish immigrants brought their recipes for pasties and meat pies. In the northern states, pumpkin pie was popular, as pumpkins were plentiful. Once the British had established Caribbean colonies, sugar became less expensive and more widely available, which meant that sweet pies could be readily made. Molasses was popular in American pies due to the rum and slave trade with the Caribbean Islands, although maple syrup was an important sweetener in Northern states, after Indigenous people taught settlers how to tap maple trees and boil down the sap. In the Midwest, cheese and cream pies were popular, due to the availability of big dairy farms. In the US south, African-Americans enjoyed sweet potato pies, due to the widespread availability of this type of potato. By the 1870s, the new science of nutrition led to criticism of pies, notably by Sarah Tyson Rorer, a cooking teacher and food editor who warned the public about how much energy pies take to digest. Rorer stated that all pie crusts "...are to be condemned" and her cookbook only included an apple tart, jelly and meringue-covered crackers, pâté, and a "hygienic pie" which had "apple slices or a pumpkin custard baked in biscuit dough". In 1866, "Harper's Magazine" included an article by C.W. Gesner that stated that although we "...cry for pie when we are infants", "Pie kills us finally", as the "heavy crust" cannot be digested. Another factor that decreased the popularity of pies was industrialization and increasing movement of women into the labour market, which changed pie making from a weekly ritual to an "occasional undertaking" on special occasions.