20,000 years ago, the world suffered in the depths of the last ice age. For several thousand years, global average temperatures stayed 15 degrees Fahrenheit, that's about 8 degrees celcius below what they're today, and mile thick glaciers covered much of North America, Europe, and Asia; outside the ice-covered regions, it was so dry that survival became difficult in most areas. Some areas where people'd been living became inhospitable, and in some other places, new barriers of ice or desert separated groups of people, but against all odds, some people found ways to survive in severe conditions as far north as Siberia. The ice age not only created barriers, it also created bridges with so much water locked up in ice, sea levels dropped, exposing land and connected Siberia and Alaska, a few people in Siberia took advantage of this bridge, moving into present-day Alaska, and later, down into other parts of North America, maybe they followed migrating herds or maybe, they traveled in small boats, down the Pacific coast, or maybe they did both. No matter how they got there, those people who get there became the ancestors of today's Americans. In just a short time, humans from a small corner of Africa had populated all continents except Antarctica, and in there new homes, their languages began to differentiate to form the precursors of today's languages. Some populations probably didn't survived the ice age and those that did often became more isolated from other groups, scattered around the world, these small populations became more being culturally, and genetically distinct from one another. How would cultural innovations helped a few of these groups to expand dramatically over the next several thousands years.