A team of scientists led by Dr Thilo Gross of the University of Bristol has combined depictions of lions, wild dogs, elephants and other creatures from Egyptian antiquity with paleontological and archeological evidence to assemble a detailed record of the large-bodied mammals that lived and became extinct in Egypt over the past six millennia.
The obverse and reverse surfaces of a 5,150-year-old siltstone ceremonial palette discovered at Hierakonpolis, Egypt. The object is surmounted and framed by two wild dogs (Lycaon pictus) clasping one another’s paws; other species include ostrich, hartebeest, wildebeest, ibex, oryx, and giraffe; some fictitious animals are also depicted, including serpent-necked panthers, or ‘serpopards,’ and a plausible griffin. Image credit: Ashmolean Museum.
Around 6,000 years ago, there were 37 species of large mammals in Egypt, but only 8 species remain today.
Among the species recorded in artwork from the late Predynastic Period (before 3100 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,” explained Dr Justin Yeakel of the Santa Fe Institute, who is the first author of a paper published in the Proceedings of the National Academy of Sciences.
“There were multiple species of gazelles and other small herbivores, which are important because so many different predators prey on them.”
The presence/absence of mammals across 6,000 years of Egyptian history; all dates are in years before present; the first time bin does not have a definitive starting date, generally representing the Late Pleistocene; the white circles denote the first time interval of a recorded species occurrence if it was not initially present; the black circles denote the last time interval of a recorded species occurrence if it is not extant; the color gradient is the probability that a given species is locally extinct for the treatment allowing first/last occupation to vary across two time bins before and after the recorded event; G-R – Greco-Roman period. Image credit: Justin D. Yeakel et al.
“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.”
Dr Gross, Dr Yeakel and their colleagues identified five episodes over the past 6,000 years when dramatic changes occurred in Egypt’s mammalian community, three of which coincided with extreme environmental changes as the climate shifted to more arid conditions.
These drying periods also coincided with upheaval in human societies, such as the collapse of the Old Kingdom around 4,000 years ago and the fall of the New Kingdom about 3,000 years ago.
227 animals, including elephants, lions, a giraffe, and sheep, cover both sides of the ivory handle of a ritual knife from the Predynastic Period in Egypt. Image credit: Charles Edwin Wilbour Fund / Brooklyn Museum.
“There were three large pulses of aridification as Egypt went from a wetter to a drier climate, starting with the end of the African Humid Period 5,500 years ago when the monsoons shifted to the south. At the same time, human population densities were increasing, and competition for space along the Nile Valley would have had a large impact on animal populations,” Dr Yeakel said.
The most recent major shift in mammalian communities occurred about 100 years ago.
The analysis of predator-prey networks showed that species extinctions in the past 150 years had a disproportionately large impact on ecosystem stability.
“This may be just one example of a larger pattern. We see a lot of ecosystems today in which a change in one species produces a big shift in how the ecosystem functions, and that might be a modern phenomenon. We don’t tend to think about what the system was like 10,000 years ago, when there might have been greater redundancy in the community,” Dr Yeakel said.
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Justin D. Yeakel et al. Collapse of an ecological network in Ancient Egypt. PNAS, published online before print September 08, 2014; doi: 10.1073/pnas.1408471111
