Unraveling an ecological network: 6000 years of anthropogenic and climatic impacts on an Egyptian food web
Modern animal communities are vestiges of rich ecological ancestries, shaped over time by evolutionary, climatic, and more recently anthropogenic effects. It is not well understood to what extent climatic and anthropogenic processes structure animal communities, nor is the timescale over which they occur known. Understanding the drivers of ecological change in the past is important because similar mechanisms may influence the future trajectories of modern ecosystems. Here we use compilations of palaeontological, archaeological, and historical information of species occurrences, as well as sequences of artistic depictions of mammalian predators and prey in ecological settings to reconstruct the patterns of extinction in Egypt over the past 6000 years. We then determine whether the structure of mammalian predator-prey networks changed over Egyptian history, and to what extent these changes are expected to have influenced the dynamic stability of Egyptian animal communities.
Our results demonstrate that the pattern of species extinction in Egypt cannot be explained by random extinction models, and that large changes in the predator:prey ratio coincided with abrupt aridification events. Moreover, we show that the loss of species in the last 200 years disproportionately impacted dynamic stability, indicating that recent anthropogenic effects can be unexpectedly destabilizing. These results document the collision of an essentially intact Pleistocene community with one of the earliest technologically advanced human civilizations. The timing and patterns of historical ecosystem collapse provides an opportunity to assess whether changes in climate compared with the direct and indirect effects of increased human densities altered the structure and functioning of ecological communities.