DNA solves the mystery of how these mummies were related

The duo had the same mother, but different dads.

A pair of ancient Egyptian mummies, known for more than a century as the Two Brothers, were actually half brothers, a new study of their DNA finds.

Mamma's Boys. Ancient Egyptian mummies known as the Two Brothers, found in these coffins, had the same mother but different fathers, DNA evidence indicates.

These two, high-ranking men shared a mother, but had different fathers, say archaeogeneticist Konstantina Drosou of the University of Manchester in England and her colleagues. That muted family tie came to light thanks to the successful retrieval of two types of DNA from the mummies’ teeth, the scientists report in the February Journal of Archaeological Science: Reports. The finding highlights the importance ancient Egyptians placed on maternal lines of descent, Drosou’s group contends.

Questions have swirled about the biological backgrounds of the mummified men ever since they were found together in a tomb near the village of Rifeh in 1907. The tomb dates to ancient Egypt’s 12th Dynasty, between 1985 B.C. and 1773 B.C. Coffin inscriptions mention a female, Khnum-Aa, as the mother of both men. And both mummies are described as sons of an unnamed local governor. It has always been unclear if those inscriptions refer to the same man, but discoverers decided the mummies were full brothers, because the two were buried next to each other and had the same mother.

Over time, differences discovered in the men’s skull shapes and other skeletal features raised suspicions that the Two Brothers were not biologically related at all. And some researchers argued that the inscriptions indicating the men had the same mother were misleading.

Adding to those doubts, a 2014 paper reported differences between the two mummies’ mitochondrial DNA, suggesting one or both had no biological link to Khnum-Aa. Mitochondrial DNA typically gets inherited from the mother.

But that study extracted ancient DNA from liver and intestinal samples using a method susceptible to contamination with modern human and bacterial DNA, Drosou’s team argues. In the new work, researchers isolated and assembled short pieces of mitochondrial and Y-chromosome DNA from both mummies’ teeth using the latest methods. The Y chromosome determines male sex and gets passed from father to son. This approach minimizes potential contamination from modern sources (SN Online: 5/31/17).

That new DNA evidence “proves the hieroglyphic text [on the mummies’ coffins] to be accurate,” at least in saying the mummified men had the same mother, says Egyptologist and study coauthor Campbell Price, curator of the Egypt and Sudan collections at the Manchester Museum in England.

Unlike the deference given to Khnum-Aa as a named parent of both interred individuals, he says, the coffin inscriptions must refer to different fathers who were considered peripheral family members and thus left unnamed. “Power may have been transferred down the female line rather than simply by a son inheriting [high rank] from his father,” Price suggests. Khnum-Aa’s background, social standing and genetic makeup, however, remain a mystery.

Genetic evidence that two half brothers were buried in the same tomb and placed in coffins that name only their mother makes sense, says Egyptologist Joann Fletcher at the University of York in England. Many written sources from ancient Egypt show precedence to the maternal line, “from the official lists of Egypt’s early kings whose names are accompanied by those of their mothers to nonroyal individuals, who likewise cite only their mother’s name,” Fletcher explains.   

Dates of death on the mummies’ linen wrappings suggest that Khnum-Nakht died first, at around age 40, Price says. A few months later, Nakht-Ankh died at about age 60. The causes of their deaths are unknown.

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By Bruce Bower / Science News Behavioral Science Writer

Bruce Bower has written about the behavioral sciences since 1984. He often writes about psychology, anthropology, archaeology and mental health issues. Bruce has a master's degree in psychology from Pepperdine University and a master's degree in journalism from the University of Missouri. Following an internship at Science News in 1981, he worked as a reporter at Psychiatric News, a publication of the American Psychiatric Association, until joining Science News as a staff writer. In 1996, the American Psychological Association appointed Bruce a Science Writer Fellow, with a grant to visit psychological scientists of his own choosing. Early stints as an aide in a day school for children and teenagers with severe psychological problems and as a counselor in a drug diversion center provided Bruce with a surprisingly good background for a career in science journalism.

(Source: sciencenews.org; January 16, 2018; https://www.sciencenews.org/node/194589)
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