Radiocarbon Dates in Québec: Analyzing Paleopopulations and Environmental Change

English Abstract:

The extent to which North American paleopopulations influenced the environment and contributed to global atmospheric change remains unknown, partly due to a lack of data concerning population densities. The analysis of archaeological radiocarbon dates is one way of obtaining paleopopulation densities since the frequency of dates can be interpreted as being proportional to the number of people living around a site. The Canadian Archaeological Radiocarbon Database (CARD) contains more than 35,000 radiocarbon dates derived from cultural and paleoecological material spanning the last 25,000 years. These data form the basis of our study of past human-ecosystem-climate dynamics.

A first step in the analysis of any database is to identify problematic data, which can occur due to many causes, including contamination by older or younger carbon and stratigraphic problems. To obtain an accurate representation of human impact on North American ecosystems, these dates must be identified and corrected, and additional dates must be obtained for locations with insufficient data. The issue of taphonomic loss must then be addressed such that the true human population density is revealed. Although shown to provide reasonable results at a continental scale, more work is needed to determine at what point the “dates as data” approach is applicable at regional scales.

Six hundred and sixty two CARD dates from Québec spanning 13,000 years were analyzed as a function of ecoregion. Most dates are located in coastal regions, along the St. Lawrence River, or are associated with resource development projects. All ecoregions display a similar trend in the frequency of dates, which generally increases towards the present, with the exception of a sharp increase between 1,000 and 3,000 cal BP. Further analyses will reveal whether the sharp increase in date frequency is a result of taphonomic loss or population growth. Humans appear to have settled all ecoregions following the retreat of the Laurentide Glacier. One site in coastal northern Québec, where glacial ice remained until approximately 7,000 years ago, had a clearly anomalous date (8,428 cal BP). The uneven spatial distribution of sites, a consequence of archaeological activity, also needs to be considered when mapping past population distributions.