The first people who traveled to the Western Hemisphere arrived from Siberia approximately 15,000-20,000 years ago, according to archeological reports recognized as most correct by the Smithsonian Institution and the National Geographic Society.

Other investigators with less certain evidence claim people crossed the Bering Strait perhaps as long as 40,000 years ago; a few others claim seafarers may have arrived on the western coast of South America or the eastern shores of North America before humans traversed the Bering Strait to North America.

The Bering Sea was much lower back then than now, because thick ice covered the northern third of our planet’s landmass and contained much water in frozen form. As the Earth gradually warmed and the ice melted, the oceans rose and many lakes formed, including North America’s Great Lakes and many bodies of water in what are now the United States, Canada, Europe and Asia.

The first immigrants and their dogs traversed from northeastern Asia to what is now Alaska either on dry land, a frozen Bering Sea or they used watercraft to navigate their way along oceanic shorelines during summer when enough of the ice had melted. Over the next few millennia their descendants spread southward and eastward.

The first immigrants to the Western Hemisphere probably consumed mostly fish such as salmon, mollusks such as clams, rabbits, berries and root plants, even though they may have encountered mastodons, mammoths, North American camels and horses (both were smaller than the modern-day animals), giant sloths and saber-tooth tigers.

The immigrants’ descendants gradually exterminated those species, leaving bison, antelope, deer and elk on grasslands south of the receding glacier. By approximately 10,000 years ago the first people had migrated to almost all regions of North and South America and to nearby islands.

Archeologists say the first farmers in the Western Hemisphere began raising crops about 7,000 years ago in Central America. Our agrarian predecessors were innovative and astute observers of foods that could be gathered and reproduced through cultivation techniques, and enhanced through selection of the most nutritious and beneficial cultivars and genetic mutations.

For example, they probably found one or more teosinte plants, the predecessor to modern corn, which formed its “ear” of seeds on the stalk instead of on the tassel flower, which they reproduced.

Besides corn (also called maize), these innovators developed farming methods for such agricultural crops as potatoes, peppers, lima beans, green beans, pineapple, chocolate, papaya, tomatoes, squash and sunflowers, and agave and guava for alcoholic brews called pulque.

Cities with 40,000 inhabitants or more necessarily depended on nearby farmers for food. Sophisticated cultures emerged in Central America (such as the Mayans), portions of South America (such as the Aztecs), several parts of what are now Mexico and the Southwest U.S. (such as the Anasazi and Hohokam) and farther north, such as Cahokia (in Illinois) and the five Iroquois nations.

Western Hemisphere crops became favored throughout the world as European explorers and conquerors of the Americans took preserved foods and seeds back to Europe, beginning with the Spanish conquistadors some 500 years ago. As cultivation of these foods spread to Asia, Africa, Australia and many island nations, appetites for these items expanded.

Domestication of livestock was slower and less extensive in the Americas than in the Old World, partly because there were fewer species suited for domestication. South American natives tamed and raised guinea pigs and turkeys for food and llamas for carrying packs.

The first people on both continents had domesticated dogs. They sometimes consumed dogs for food when little else was available, but historical evidence suggests dogs were mostly used for hunting, guard duties, pulling travois (two wooden poles lashed to dogs with harness) for transporting things and companionship.

Although agriculture in the Americas emerged several thousand years after cultivation of crops and the domestication of sheep and goats occurred in Southwest Asia, agriculture’s development in the new continents was independent from Asia, where it began some 5,000-7,000 years earlier in the Fertile Crescent called Mesopotamia.

Agriculture in the Western Hemisphere was mostly successful. Elaborate irrigation systems that capitalized on gravity for water flow were devised by the Anasazi and other early farmers in the Southwest. They dug channels several feet wide and a couple feet deep that fed ever-smaller channels to distribute water runoff from heavy rains or melting snow onto ground cultivated for crops.

Mostly similar irrigation systems were developed by natives in the Andes, and in eastern North America and the Midwest. The original natives of North America and Caribbean islands provided agricultural produce to European immigrants, including their eventual conquerors.

Mandan Sioux provided corn, beans, squash, sunflower seeds and pumpkins to the Lewis and Clark Corps of Discovery who with stayed with them during the winter of 1804-05.

Without these first farmers in the Western Hemisphere, diets – and history – might be much different today in the Americas, and throughout the world.

Dr. Mike Rosmann is a psychologist and farmer in western Iowa. The views and opinions expressed in this column are those of the author and not necessarily those of Farm World. Readers may contact him at mike@agbehavioralhealth.com