Depictions of animals in ancient Egyptian artifacts have helped scientists assemble a detailed record of the large mammals that lived in the Nile Valley over the past 6,000 years. A new analysis of this record shows that species extinctions, probably caused by a drying climate and growing human population in the region, have made the ecosystem progressively less stable.

 

The study, published in Proceedings of the National Academy of Sciences (PNAS), found that local extinctions of mammal species led to a steady decline in the stability of the animal communities in the Nile Valley. When there were many species in the community, the loss of any one species had relatively little impact on the functioning of the ecosystem, whereas it is now much more sensitive to perturbations.

 

Around six millennia ago, there were 37 species of large-bodied mammals in Egypt, but only eight species remain today. Among the species recorded in artwork from the late Predynastic Period (before 3,100 BC) but no longer found in Egypt are lions, wild dogs, elephants, oryx, hartebeest, and giraffe.

 

What was once a rich and diverse mammalian community is very different now. As the number of species declined, one of the primary things that was lost was the ecological redundancy of the system. There were multiple species of gazelles and other small herbivores, which are important because so many different predators prey on them. When there are fewer of those small herbivores, the loss of any one species has a much greater effect on the stability of the system and can lead to additional extinctions.

 

 

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