Ancient Egyptian Mummies From 4,000 Years Ago Shared a Mommy, DNA From Teeth Reveals

The coffins of two mummies known as the Two Brothers. Manchester Museum, The University of Manchester

Two millennia-old Egyptian mummies long believed to be brothers are actually half siblings, according to a new paper published in the Journal of Archaeological Science: Reports. The researchers argue the two men shared a mother but had different fathers, which may in turn suggest that the civilization valued a mother's influence more than scholars had realized.

"Power may have been transferred down the female line rather than simply by a son inheriting [high rank] from his father," co-author Campbell Price, a curator at the museum, told Science News.

The researchers analyzed ancient DNA found in the teeth of two mummies now located at the Manchester Museum in the U.K. The mummies, which date to between 1985 and 1773 B.C., belonged to men named Nakht-Ankh and Khnum-Nakht. Khnum-Nakht died first and was mummified hastily; he was followed about six months later by Nakht-Ankh, who was 20 years older than his alleged brother.

The mummies were buried together and each coffin reports that its resident is the son of a woman named Khnum-aa, so researchers have tended to assume they were brothers, even though both coffins refer to a father only with his title, not an individual name. The tomb was found undisturbed in 1907 at Deir Rifeh in central Egypt and the mummies were unwrapped in 1908.

But a 2014 genetic analysis paired with study of the shape of the two mummies' skulls threw doubt on that. Perhaps the two men were adopted, or were each sons of different women with the same name. (The same study also suggested that both men were infected with a parasite called Schistosoma, which can cause fever and chills and infect people for years on end.)

So the team behind the new paper wanted to take another stab at piecing together what—if any—family tie the two mummies shared. They managed to pull DNA from the mummies' teeth, a better source than what the previous study used, to spell out the genome. They analyzed mitochondrial DNA, which is separate from a person's main genetic sequence and is inherited only from the mother, and also Y chromosome DNA, which is found on one of the sex chromosomes in males.

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The mitochondrial analysis found that the two men's maternal inheritances were similar enough they could have come from the same woman. But their Y chromosomes were quite different. Taken together, those two types of sequences supported the notion that Nakht-Ankh and Khnum-Nakht shared a mother but had different fathers, making the inscriptions on their coffins pretty accurate.

The researchers say that the different treatments of mothers and fathers in the inscriptions suggest that maternal heritage was more important to the ancient Egyptians than paternal heritage was.