The relative roles of humans and climate on the extinction of Pleistocene megafauna is still unclear for many species. At the end of the last ice age, severe climatic changes occurred around the same time as an increase in human occupation and activity, which complicates the discussion. Furthermore, behavioural characteristics of a species can play a key role in the process of extinction and how vulnerable a species is. Species that rely on geographically fixed resources can be particularly at risk: if through either climatic or human impacts these resources become lost or inaccessible, it can have a profound impact on the survival of the species. In order to fully understand the relative impacts of humans, climate and behaviour, we need cutting-edge methods from multiple scientific fields: ancient DNA, genomics, climate science and theoretical population modelling.
This MSCA used these tools to investigate the population dynamics of the extinct cave bear (Ursus spelaeus species complex). Cave bears were large herbivorous bears that lived in mountainous areas in Europe and western Asia. Cave bears used caves to hibernate, and previous research has suggested that, at least for some populations, these bears consistently returned to their birth cave for hibernation over many generations. If through human actions or climatic changes these caves become inaccessible, this could have been detrimental for local populations, and in turn for the species as a whole. Using palaeogenomics and population modelling, we reconstructed long-term population dynamics of this iconic Pleistocene species and gained an understanding of which particular factor (humans, climate or access to caves) has played the most critical role in the extinction process of the cave bear 25,000 years ago.
As an extinct species, cave bear represent a case where the species failed to adapt to the environmental and ecological pressures they faced, resulting in extinction. A more detailed understanding of that process will help formulate strategies to help avoid the same outcome for currently threatened species.
