Ancient irrigation system at Tell Zeidan supported spread of prehistoric parasite
A parasite egg discovered in a 6,200-year-old skeleton in Syria has provided the earliest known evidence that the use of irrigation in farming triggered the spread of schistosomiasis, a parasitic disease, according to a recent study.
Researchers from Cambridge, Cyprus and the University of Chicago’s Oriental Institute studied skeletal remains excavated from a Chalcolithic-period cemetery at Tell Zeidan, located in the Euphrates river valley in northern Syria. Their findings are presented in the medical journal The Lancet Infectious Diseases.
One individual suffered from an infection caused by a schistosome egg discovered in the skeleton’s pelvic area. Schistosomiasis, also known as snail fever, can lead to anemia, kidney failure and bladder cancer.
Tell Zeidan was a Mesopotamian farming settlement in the sixth and fifth millennia B.C. Archaeobotanical evidence in the form of carbonized seed remains demonstrates that wheat and barley were cultivated at Tell Zeidan, despite the region’s extreme aridity.
“Crops can only succeed with some form of irrigation,” said Oriental Institute director Gil Stein, who coauthored the Lancet study, in an email to Bible History Daily. “Based on that, we infer that irrigation must have been used for farming at Zeidan.”
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Tell Zeidan is located right next to the Balikh River where it meets the Euphrates, which would have provided an immediate source of water for irrigation.
“Irrigation agriculture requires that people spend a lot of time working in standing or slow flowing water— precisely the environment where the schistosome fluke and its host snail flourish,” Stein explained. “This is why schistosomiasis is so prevalent in irrigation farming societies of the Middle East, such as in Egypt and Mesopotamia.”
What other factors led the researchers to conclude that the individual infected with schistosomiasis contracted the parasite wading through an irrigation system rather than natural freshwater?
“We currently have no evidence for schistosomiasis before the invention of irrigation in the mid-sixth millennium B.C.,” said Stein. “Putting that all together, it’s a reasonable hypothesis that once irrigation agriculture started being practiced, then people would have been exposed much more frequently and for longer periods of time to the parasite, greatly increasing their odds of becoming its unwilling host.”
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