New carbon dates link climatic change with human colonization and Pleistocene extinctions

Drastic ecological restructuring, species redistribution and extinctions mark the Pleistocene-Holocene transition, but an insufficiency of numbers of well-dated large mammal fossils from this transition have impeded progress in understanding the various causative links(1). Here I add many new radiocarbon dates to those already published on late Pleistocene fossils from Alaska and the Yukon Territory (AK - YT) and show previously unrecognized patterns. Species that survived the Pleistocene, for example, bison ( Bison priscus, which evolved into Bison bison), wapiti (Cervus canadensis) and, to a smaller degree, moose (Alces alces), began to increase in numbers and continued to do so before and during human colonization and before the regional extinction of horse ( Equus ferus) and mammoth (Mammuthus primigenius). These patterns allow us to reject, at least in AK - YT, some hypotheses of late Pleistocene extinction: 'Blitzkrieg' version of simultaneous human overkill(2), 'keystone' removal(3), and 'palaeo-disease'(4). Hypotheses of a subtler human impact and/or ecological replacement or displacement are more consistent with the data. The new patterns of dates indicate a radical ecological sorting during a uniquely forage-rich transitional period, affecting all large mammals, including humans.