Andrew Somerville, Iowa State University

An unexpected discovery by an Iowa State University researcher suggests that the first humans may have arrived in North America more than 30,000 years ago – nearly 20,000 years earlier than originally thought.

Andrew Somerville, an assistant professor of anthropology in world languages and cultures, says he and his colleagues made the discovery while studying the origins of agriculture in the Tehuacan Valley in Mexico. As part of that work, they wanted to establish a date for the earliest human occupation of the Coxcatlan Cave in the valley, so they obtained radiocarbon dates for several rabbit and deer bones that were collected from the cave in the 1960s as part of the Tehuacan Archaeological-Botanical Project. The dates for the bones suddenly took Somerville and his colleagues in a different direction with their work.

The date ranges for the bone samples from the base of the cave ranged from 33,448 to 28,279 years old. The results are published in the academic journal Latin American Antiquity. Somerville says even though previous studies had not dated items from the bottom of the cave, he was not expecting such old ages. The findings add to the debate over a long-standing theory that the first humans crossed the Bering Land Bridge into the Americas 13,000 years ago.

Wow! Fascinating stuff.