Serpents that bit ancient Egyptians slither into focus

Researchers combined ancient climate data with modeling of modern habitats to identify fanged offenders

If a snakebitten patient stumbled into an Egyptian physician’s office some 2500 years ago, the doctor might have reached for a papyrus scroll describing 34 snakes and their bites in hieratic script used by ancient Egyptians, with advice on how to treat them. This ancient manual is considered one of the world’s first medical texts.

Since the scroll was first translated 60 years ago, researchers have fiercely debated the identities of the serpents it describes. Now, researchers have used an ecological technique called niche modeling to confidently name 10 of these snakes. Today, Egyptian doctors wouldn’t find the scroll very useful: Of the species pinpointed, none still live within Egypt’s modern borders, the team reported earlier this month in Environmental Archaeology. Even so, experts say the tome offers a glimpse into human-animal interactions of the distant past.

“It’s sort of mind-blowing” that ecological modeling could help answer questions about the health of ancient people, says Gerardo Martin, a disease ecologist at the National Autonomous University of Mexico, Mérida, who was not involved in the work. “It’s a very creative use of ecological knowledge.”

Egyptologists think the snakebite manual was penned by the priests of Serket, the ancient Egyptian goddess of scorpions and other venomous creatures, as well as rebirth. Her priests were considered magicians or doctors because of their healing skills. In the late 1800s, Charles Edwin Wilbour, a U.S. journalist and anthropologist purchased the scroll—it’s unclear from whom—and his heirs donated it to the Brooklyn Museum, where it is housed today. It is the only known version of this document. Researchers have dated the scroll to the 6th century B.C.E., but it’s believed to be a copy of a much older text. Several modern researchers have tried to ascertain the listed species based on the priests’ descriptions, but have come up with conflicting answers.

To learn more, anthropologist Isabelle Winder and venom ecologist Wolfgang Wüster, both at Bangor University, asked their graduate student, Elysha McBride, to try an approach traditionally used to predict a species’ probable habitat range. The technique, called niche modeling, considers the environmental conditions where a species now lives, then incorporates climate data from elsewhere to figure out other suitable homes.

Conservationists use the method to figure out where to implement protective measures for endangered species. McBride wound the clock back on the technique, using it to predict where certain snakes likely lived in the past by incorporating ancient climate data.

She first reviewed the list of species proposed by other researchers. Because bites were the handbook’s area of concern, she focused on 10 species that are considered particularly venomous or aggressive. Using publicly available data, she plotted where each species lives now and analyzed 19 climate variables—such as rainfall and average temperature—to give her model a good idea of the species’ preferred habitat. She then added climate data from up to 6000 years ago and asked the model to predict which species could have slithered through ancient Egypt’s savanna and scrublands.

That habitat would have been suitable for nine of the 10 species studied, including the black mamba, puff adder (which today is responsible for the most snake fatalities in Africa), and the Palestine viper, the Bangor team reported on 7 October. The model suggested  the 10th species, the rhombic night adder (Causus rhombeatus), lived just outside Egypt’s ancient borders, but may still have been known to the priests of Serket, McBride says.

“It is surprising to see that there were probably 10 species living in Egypt that are no longer living there,” says Anooshe Kafash, a paleoanthropologist at the Stiftung Neanderthal Museum who was not involved with the work. Beyond helping clarify how ancient Egyptians interacted with snakes, this approach can be useful “in answering mystery questions about how ancient humans have interacted with other plants and animals,” he adds. For example, he is using niche modeling to determine how Neanderthals and anatomically modern humans spread through time.

Martin says it’s a “fascinating” use of the application. Although fossil evidence attested to the presence of some of these snakes, the study provides fresh evidence the others were there, too. “That’s a good thing,” he says. “It opens up many avenues to understanding how some diseases have emerged in the past.” Still, he cautions that it’s not a sure bet that the habitats these species stick to today are the same ones they preferred thousands of years ago. Their preferences may have evolved over time, he suggests, so additional modeling would be needed to make the results “more robust.” 

doi: 10.1126/science.adl4033

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