Who were the first humans to inhabit North America? According to the now familiar story, mammal hunters entered the continent some 12,000 years ago via a land bridge that spanned the Bering Sea. Distinctive stone tools belonging to the Clovis culture established the presence of these early New World people. But are the Clovis tools Asian in origin? Drawing from original archaeological analysis, paleoclimatic research, and genetic studies, noted archaeologists Dennis J. Stanford and Bruce A. Bradley challenge the old narrative and, in the process, counter traditional--and often...