Farming provides 10 to 100 times more calories per acre than hunting and gathering, and probably became popular due to the overhunting of large animals combined with the skill of domesticating seeds.1 Inventions such as the wheel (invented over 5,500 years ago), the plow (5,000 years ago) and irrigation (8,000 years ago) were used since ancient times.2,3 Most of the farm animals we are familiar with today were domesticated by cultures 8,000 years ago.3 However, in the U.S., there have also been many changes that led to the current level of production and long-term prosperity. By the 1700's, American farmers used horses, the steam engine and the cotton gin (invented 1794).4
Today the United States (U.S.) is the largest exporter of food, sending agricultural products all over the world. The U.S. has the most efficient and productive agricultural system, exporting more than it imports. There are over two million farms in the U.S., 99% of them are family-owned and nearly 1/3 of American farmers are women.5 From 1900 to 2011 the world population exploded from 1.6 billion to 7 billion people, yet today, the world's farmers, including U.S. farmers produced enough food to feed over 8 billion people.3 However, this improvement in production or quantity through modern farming has led to new problems. Some of them are related to nutrition.
A hundred years ago, more than half of Americans were farmers; today only 2% are.3 Farmers were skilled in many trades and family farms produced a diverse number of crops and animal products. Today farms specialize to increase efficiency and focus on one or two crops such as growing corn or fattening beef cattle. Today instead of diversified farms we have uniform monocultures; fields that are planted with just one crop and facilities that house a single breed of animal for a single purpose.3 Chickens today, for example, are bred so that they are twice as large and grow in half as much time as chickens 100 years ago. Adding antibiotics to animal feed in the 1950's led to the discovery that farm animals would grow much faster with less feed using antibiotics. Today, >70% of antibiotics sold in the U.S. are used for livestock production, not for humans.6 While crop diversity helped to suppress weeds and other pests, monoculture farming (just one crop at a time) led to the need for great pesticide use.3
These changes in agriculture paved the way for the modern American diet. Meat and poultry became more available and easier to obtain in larger quantities. Grains could be produced massively leading to use in snack foods, high-fructose corn syrup, etc. For many Americans, even as farming became less diversified, the American diet did as well, resembling what we see today in modern fast food restaurants. This eliminates many foods that farmers once produced and created a system heavily processing grains, i.e. stripping wheat of its germ, polishing rice to make white rice, etc. The significant changes in agriculture in the U.S. in the 20th century explain the change in diet, and consequent loss of dietary fiber for Americans of all ages and social classes.