Scientists extract DNA from Egyptian bird mummies to find out where they came from

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When Sally Wasef descended into the ancient Egyptian necropolis of Saqqara in search of mummified ibis birds to extract DNA from, she was not disappointed.

She describes a dark, underground street or corridor about a kilometre long, lined with rooms on either side — "and each room was filled from floor to ceiling with jars that contain the sacrificed ibises."

There are an estimated six million sacred ibis mummies in the ancient Egyptian catacombs, including 1.5 million in Saqqara alone, all of them sacrifices to Thoth, the Egyptian god of magic, writing and wisdom. 

"It was fascinating to find those numbers, huge numbers of birds," Wasef, a paleogeneticist at Griffith University in Australia, told As It Happens host Carol Off. "And the question that was coming up is where they got them from."

Factory farms or free-range?

The ancient Egyptians saw the ibis as animal representatives of the god Thoth, Wasef said.

"If you have a wish that you wanted granted from the gods you worship, you offer them something," she said. "So they use the ibis sacrificial offerings to the god Thoth to ask him to grant a wish or to thank him for already doing a favour to them."

These ibis sacrifices were so common that many historians believe they were farmed by priests in massive industrial hatcheries specifically for that purpose. It's a theory that's backed up in some ancient texts.

But new research from Wasef and her colleagues suggests otherwise. 

Her team analyzed the mitochondrial DNA from the mummified birds and compared it to modern samples from ibises across Africa. The birds went extinct in Egypt by the mid-19th century, likely due to changes in the climate, Wasef said.

They found the mummified birds had the same genetic diversity as the wild ibis population. In industrial bird-raising operations, populations become less genetically diverse with each passing generation due to inbreeding. 

The findings were published in the journal PLOS One. 

So where did they all come from?

If the ibises weren't farmed, does that mean they were hunted? Wasef says the truth probably lies somewhere in the middle. 

"Next to each temple or each catacomb, there used to be a big lake or a wetland, which is a natural place for the ibis to hang around, and our theory is that priests used to feed them, " Wasef said.

"And when you feed ibises, they come to you."

But the findings have proven controversial. 

Pontus Skoglund, an expert in ancient DNA at the Francis Crick Institute in London, told the Guardian that Wasef's theory is plausible. But he said it's also possible the hatcheries were simply large enough that the birds retained a high level of genetic diversity.

Francisco Bosch-Puche, a University of Oxford archeologist who has worked on teams that excavated thousands of ibis mummies, told National Geographic the DNA evidence could be the result of wild ibises that were attracted to the food from hatcheries being hunted to supplement the farmed ones.

What's more, he said many mummified ibises show signs of healed fractures and infectious diseases, similar to modern captive animal populations. 

But Wasef stands by her theory.

"There is no living evidences for hatcheries ... so why you would think that every single thing survived, including the temple and catacombs, but no hatchery survived if it was attached to the temple?" she said. 

"The second thing is ancient Egyptians used to care a lot for animals, so I'm not surprised that you find a broken wing has been healed before mummification. Because basically, they are walking gods. You respect them."

Written by Sheena Goodyear. Interview with Sally Wasef produced by Katie Geleff.