Laboratory for Paleoclimatology
and Climatology
North American Subgroup:
Human-Environment Interactions
Over the Past 13ka
Michelle A. Chaput1, Bjoern Kriesche2, Matthew Betts3, Andrew Martindale4, Rafal Kulik5, Volker Schmidt2 and Konrad Gajewski1
1Laboratory
for Paleoclimatology and Climatology, Department of Geography, University of Ottawa, Ottawa, ON, Canada K1N 6N5
2Institute of Stochastics, Ulm University, D-89069 Ulm, Germany; 3Canadian Museum of History, Gatineau, QC, Canada K1A 0M8
4Department of Anthropology, University of British Columbia, Vancouver, BC, Canada V6T 1Z1; 5Department of Mathematics and Statistics, University of Ottawa, Ottawa, ON, Canada K1N 6N5
Introduction
These results are part of an ongoing research program documenting past paleodemographic change in North America for the past 13ka. They
form the first step toward being able to understand continental-scale human impacts on the North American ecosystem during the Holocene.
North American Radiocarbon Data
The Canadian Archaeological Radiocarbon Database
(CARD) contains 30k culturally-significant radiocarbon
dates from which we inferred past population density
at 500-year intervals from 13 to 0.5 ka BP using kernel
density estimation. The underlying assumption of this
approach is that a greater number of dates is indicative
of a higher population density when sampling bias, and
taphonomic and calibration effects, are accounted for.
Our results provide the very first continental-scale
spatiotemporal estimates of past demographic growth
following the colonization of the Americas.
c
b
Changes in population density (a) based on
the spatial (b) and temporal (c) distribution
of archaeological radiocarbon dates in the
CARD (Chaput et al., 2015, PNAS).
a
Global Radiocarbon Data
The CARD is now evolving into a global radiocarbon
database thanks to submissions from researchers from
around the world and currently contains > 44k dates,
although many more dates exist worldwide that have
yet to be entered. These data are crucial to the study of
past human-environment interactions at regional to
global scales and can be used to validate modelled
estimates of human land use and land cover change.
d
The CARD is freely available to researchers at
http://www.canadianarchaeology.ca/.
Humans and the Environment
The global distribution (d) of published radiocarbon dates
(updated from Chaput and Gajewski, 2015, Anthropocene).
Quercus 9750 BP
Quercus 11250 – 11750 BP
We are currently performing a statistical comparison of
our population density estimates with spatiallycontinuous vegetation abundance maps we created
using pollen data from the Neotoma Paleoecology
Database.
Using spatial cross-correlation methods, we
have found high correlations between changes in
population density and the vegetation abundance of
specific taxa known to be used by Paleoamericans
including Castanea and Quercus. Correlations with taxa
such as Picea and Pinus are expectedly low, as these
taxa did not directly provide ecosystem services to
humans in the past.
e
f
Population 850 – 1350 BP
References
Chaput, M.A., and Gajewski, K. 2015. Radiocarbon Dates as Estimates of
Ancient Human Population Size. Anthropocene, in press.
Chaput, M.A., Kriesche, B., Betts, M., Martindale, A., Kulik, R., Schmidt, V.
and Gajewski, K. 2015. Spatiotemporal Distribution of Holocene
Populations in North America. PNAS 112(39): 12127-12132.
Please contact M. Chaput ([email protected] ) with questions. We
would like to acknowledge funding from the Ontario Graduate Scholarship,
the Natural Sciences and Engineering Research Council of Canada , the
Canadian Association of Palynologists and the German Academic Exchange
Service.
h
g
By creating spatially-continuous maps of vegetation abundance through
time (e) from pollen time series we can compare maps of vegetation
change (f) to population change (g) and obtain cross-correlation estimates (h).