Clocking the First Americans

Abstract

The antiquity of the first Americans is one of the most controversial issues in American archaeology, and it must be resolved to understand fully the adaptive radiation of Homo sapiens into the New World. Humans were in the Americas at least by Clovis times 11,200 years ago. Accepting that these were the first Americans, however, is complicated by claims of an even earlier presence, by the absence of a Clovis source (i.e. an Alaskan predecessor is lacking), and by the theoretical demands of explaining how or why Clovis groups apparently migrated rapidly through the hemisphere. New models from evolutionary ecology, along with possible changes in the Clovis chronology (resulting from improved radiocarbon calibration), may address some of these anomalies. But there still remains the possibility of an earlier (pre-Clovis) entry, supported by some mtDNA and archaeological evidence. The mtDNA evidence, however, is complicated by questions about the viability of the presumed founder effect (on which the mtDNA clock is based). Also, the several possible pre-Clovis archaeological sites have not yet been accepted. Resolution of the timing of the peopling of the Americas, on which several theoretical and methodological issues hinge, remains a question of developing archaeological evidence, resolving ambiguity in analytical techniques and dating methods (and rejecting ones that now appear critically flawed), and expanding search strategies. The Monte Verde site in Chile is the most viable pre-Clovis candidate, although for now neither it nor any other site resolves when and by which route humans first came to the Americas.