August 12, 2013
A fluke rainstorm at an ancient rock shelter in western Pennsylvania has brought a renowned archaeologist back to the site of where a furious debate was launched in 1973 over when the first humans came to the Americas.
As a young archaeologist, Jim Adovasio found radiocarbon evidence that humans had visited the Meadowcroft site 16,000 years ago. To archaeologists it was a stunning discovery that contradicted the so-called Clovis first theory, which dated the first settlement in the Americas to New Mexico about 13,000 years ago.
The question is important because it ties into bigger questions on how and why so many different cultures developed in the Americas, and whether they all descended from one group that came across from Asia or arrived in multiple waves.