Human populations in Europe fluctuated with changing climates between 5,500 and 3,500 years ago, according to a study.
The research, published in the journal PLOS ONE, examined Central European regions rich in archaeological remains and geologic sources of climate data.
The researchers from Kiel University, Germany, used these resources to identify correlations between human population trends and climate change.
The three areas examined were the Circumharz region of central Germany, the Czech Republic/Lower Austria region, and the Northern Alpine Foreland of southern Germany.
"Between 5,500 and 3,500 years ago, climate was a major factor in population development in the regions around the Harz Mountains, in the northern Alpine foreland and in the region of what is now the Czech Republic and Austria," the authors of the study said.
"However, not only the population size, but also the social structures changed with climate fluctuations," they said.
The team compiled over 3,400 published radiocarbon dates from archaeological sites in these regions to serve as indicators of ancient populations, following the logic that more dates are available from larger populations leaving behind more materials.
Climate data came from cave formations in these regions which provide datable information about ancient climate conditions.
These data span 3550-1550 BC, from the Late Neolithic to the Early Bronze Age.
The study found a notable correlation between climate and human populations. During warm and wet times, populations tended to increase, likely bolstered by improved crops and economies.
During cold and dry times, populations often decreased, sometimes experiencing major cultural shifts with potential evidence of increasing social inequality, such as the emergence of high status "princely burials" of some individuals in the Circumharz region, the researchers said.
These results suggest that at least some of the trends in human populations over time can be attributed to the effects of changing climates, they said.
The researchers acknowledge that these data are susceptible to skewing by limitations of the archaeological record in these regions and that more data will be important to support these results.
This type of study is crucial for understanding human connectivity to the environment and the impacts of changing climates on human cultures, they added.