Forty thousand years ago, Siberians traversed the Bering Strait to enter the Western Hemisphere. The emigration to America occurred in three waves: the Amerind (ca.40,000 BCE), the Na Dene (ca.7000 BCE), and the Eskimo/Aleut (ca. 3000 BCE). Tribes were organized in linguistic families such as the Algonkian and Athapascan in North America; the most concentrated population occurred in Central and South America. In these cultures spirits were understood...