7 Dec

Map of the Week: Migration to the Americas

By: Sophie Lichtenstein

It is widely accepted in the scientific community that humans arrived to the Americas via Beringia, a land bridge that once connected Eastern Siberia to Alaska. However, the time period at which people first crossed Beringia is not entirely clear. Beringia was open for a period of about 5,000 years, beginning at least 20,000 years ago. Evidence suggests a variety of time periods when people could have arrived as early as 12,000 years ago. 

Artifacts from the Clovis people, a cultural group that existed in New Mexico, provided evidence that people were in the Americas 13,000 years ago. However, other archaeological evidence of human presence has since emerged, extending the timeline of human arrival in North America back even further. Evidence came from places known as pre-Clovis sites, some of which include Cooper’s Ferry in Idaho, Paisley Caves in Oregon, and Monte Verde in Chile. 

In February, a paper published in the Proceedings of the National Academy of Sciences identified two likely migration windows: between 24,500-22,000 years ago and 16,400-14,800 years ago. It was during these time periods that climate conditions were ideal for migration- ocean currents were weaker, winter sea ice bridged island gaps, and ice melt in the summer made transportation for food and water possible.  

While the Beringia land bridge theory is the most widely accepted theory of migration to the Americas, there are two other theories, each with a caveat. The Trans-Pacific Migration Theory suggests that inhabitants of Australia or other Pacific Islands sailed to South America based on a genetic signal of shared ancestry of some “Population Y” between South Americans and people from Australasia. Some geneticists believe that the genetic signal originated in Asia, and the population who carried this signal separated, some migrating into South America, and some into Australasia. However, there is no archaeological or genetic support of this theory. 

The Solutrean Hypothesis connects a style of tools found in France and Spain left by a group that lived between 23,000-18,000 years ago to artifacts found on the east coast of North America. The writer of this theory, Bruce Bradley, argues that the Solutreans were some of the earliest humans in the Americas, and their tools developed into Clovis culture. Bradley’s theory says that the Solutreans used boats to expand their hunting territories, and that their expeditions eventually brought them to the coast of North America. However, others refute this, saying that it would have been near-impossible for people to cross the Atlantic during the Ice Age in small boats.