In the 1700s,90% of the population lived in rural areas,fields were still worked by hand,roads were cleared for travel between villages by hand,the labor was intensive and grueling,in the 1800s people began to migrate toward the cities as they were growing and expanding up until the industrial revolution when machines began to take over the tasks,of manufacturing and food production.In the 20th century,technology has advanced to the point where machines worked by remote control performs 90 % of the tasks that would have been otherwise performed by human labor,therefore the body doesn't need the level of caloric intake to maintain the same level of energy to function in a modern world.