The domestication of livestock for food occurred very recently in time. In most regions of the world it coincided with grain and vegetable farming, which commenced, in most cases, anywhere from 10,000 to 4,000 years ago depending on the region of the world one studies. Yet as recently as the Twentieth Century there were still small isolated pockets of people here and there who were still Hunter Gatherers. But the Peace Corp., missionaries, and others driven to do good deeds worked rapidly to eliminate those few remaining pockets of healthy people by teaching them "modern" grain farming methods to improve their food supplies. For the unfortunate late comers to modern civilization the changes in their foods have been abrupt to the extreme.
Here in the United States we have also experienced significant changes in our foods in a matter of a very few decades. For the most part the residents of the first permanent settlements (circa 1600) in what is now the United States had to live off the land. Sure they had brought with them their livestock and seeds for gardens, but hunting, fishing, and the gathering and cultivation of wild indigenous vegetables and fruits were vital and significant food sources. In 1800 about 95% of the U.S. population was still considered rural and farming (at a very minimum gardening) was nearly everyone's business. By 1920 though the rural population of the country had dropped to about 50% and in the 1970s it had dropped to 25%, which is about where it is today.
In the 1960s, even though urban numbers had risen significantly, it was not uncommon for city dwellers to still have vegetable gardens and fruit trees. But now a garden in any town, much less a city, is a rarity. Shockingly farmers too are a rarity with only one percent of our nation's population making a living off the land. But most shocking of all is the fact that most of the folks who make their living by ranching and farming do not raise their own food. They go to town and purchase most if not all of their foodstuffs!
The following quoted excerpts from the Software Toolworks Multimedia Encyclopedia regarding scurvy illustrate how fast man reacted to the first recognized nutritional deficiency disease. From our perspective today we can only assume that folks of that era must of been very ignorant. But actually they were no different than folks are today in what we call the “Information Age.”
The modern-day fatty acid imbalance of the American diet is a nutritional deficiency disease that will go down in history as one of the worst (most costly) known to man. Some American beef producers want to do something about it. But even after informing the grocery industry's meat buyers about the health problems with grain-fed beef, those major retailers say they are "not interested." They say they “don't want to mess with it.” They have “too many other meat programs.” They just “don't have the real estate” to display it. (Of course, their customer bases don't have a clue about it either.)
You be the judge. What kind of people would knowingly sell you a defective product?