Two distinct groups of humans arrived in the Americas 14,000 years ago

There's a long running debate among archaeologists about who the first humans to arrive in the Americas really were. There are two distinct sets of ancient tools that we find in North America, called the Western Stemmed and Clovis traditions. The question is, did the cultures that made Western Stemmed tools come to… » 7/14/12 9:40am 7/14/12 9:40am