Reconstructing past human populations: archaeological data and uncertainty

Background/Question/Methods

Prior to intense urbanization, the success of human populations to become locally established reflected a complex combination of bottom-up pressures. Much like other animal populations, changes in local climate and access to resources affected where humans could persist and reproduce. Archeological evidence regarding the ecology of prehistoric human populations is growing, and with this increase in data comes a need to develop appropriate tools for analysis. Here we present data regarding human settlements of Sanak Island (Aleutian Islands: Alaska) dating back almost six thousand years. We compare assumptions regarding carbon dating techniques and human habitation to determine an appropriate measure of error for population size estimates. Using these population size estimates in conjunction with zooarchaeological data, we investigate how factors such as changes in climate and local food availability affected population growth and decline on Sanak Island over the past six thousand years. By disentangling the correlation between climate and other ecological factors, we are better able to understand how human populations were connected with their environment.  

Results/Conclusions

In comparing methods and assumptions of carbon dating procedures, we find little difference between previous 'coarse-grained' time windows (assuming either a normal or uniform distribution within a carbon-date-determined time window) and the more recently developed probabilistic 'fine-grained' methods. In all cases, population size estimates, and their associated errors, provide a baseline to compare with other paleoecological factors. We present methods for using these population estimates, and their associated errors, to test hypotheses regarding interactions between early human populations and environmental pressures, including climate and food availability.