A finely ground powder made by grinding cereal grains or starchy plants. Flour often refers to wheat flour, but it can be made from rye, barley, corn (maize), buckwheat, rice, or other grains.
One of the oldest archaeological sites showing that humans milled wheat (separating the outer bran and germ of the wheat berry from the endosperm for easier digestion) dates from around 10,000 BCE in the south of France. However, this is just the oldest recorded example; humans in many areas around the world likely discovered milling to help them eat grains.
In 1632, the first flour mill in North America was built in
Boston, allowing English colonists to make flours similar to what they consumed
However, Native Americans had made their own flours out of acorns, corn (maize), and beans long before colonists arrived.
To make flour last longer, enabling shipments to far-off destinations, millers in the Industrial Revolution began removing the germ, which included fat that would make the flour go rancid. This is known as degermed flour.
“Flour” from the New World Encyclopedia https://www.newworldencyclopedia.org/entry/Flour
“The History of Flour” from The History of Bread http://www.historyotread.com/bread-history/history-of-flour
The Oxford Companion to Food. 3rd ed., by Alan Davidson and edited by Tom Jaine