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martes, 10 de junio de 2008

Egypt Mummies Moved for DNA Tests; Pharaoh Among Them?













Andrew Bossone in Cairo
for NGN


Three mummies have been moved from the Valley of the Kings in Luxor to the Egyptian Museum in Cairo to begin extensive studies of their origins, Egyptian authorities recently announced.

Two female mummies found in a tomb known as KV21 and one male mummy found outside the tomb of Pharaoh Seti II, who ruled Egypt from 1200 to 1194 B.C., will undergo CAT scans and DNA analysis.

Such tests could tell researchers the mysterious mummies' ancestry and could even pinpoint their identities, although it may be years before scientists can say anything definitive.

Still, the females already show promise that they may be among several Egyptian queens that archaeologists have been searching for.

Both bodies were found in the Egyptian royal pose of women: the left arm bent at the elbow with the hand clenched diagonally across the chest, and the right arm laid straight alongside the body.

"We'll try to look at the two females in KV21, because we are now looking for the families of Tutankhamun through the Egyptian Mummy Project," said Zahi Hawass, secretary general of Egypt's Supreme Council of Antiquities.

The project is a five-year plan launched by Hawass to test and catalog the DNA of every mummy in the country.

"Maybe one of them could be Nefertiti or Tiye or Kiya, we do not know," said Hawass, who is also a National Geographic Explorer-in-Residence. (The National Geographic Society owns National Geographic News.)

DNA Trace

An Egyptian team will examine the mummies' genes in what Hawass describes as the only DNA lab in the world dedicated exclusively to the study of mummies.

The best way to study ancient genes is to examine mitochondrial DNA, said Angelique Corthals, a lecturer in biomedical and forensic studies at the University of Manchester in the United Kingdom, who trained the Egyptian team.

This type of DNA is passed on through the mother and contains thousands of copies of genetic information in each cell.

Comparing mitochondrial DNA from an unidentified mummy to the genetic code of an identified female mummy can establish a family relationship.

But the technique limits researchers to tracing a mummy's lineage through its female bloodline, which may not be available in many cases.

So instead the Egyptian team will examine the male mummy's nuclear DNA, which yields just one copy of the genetic code in each cell but can be traced from either parent.

This exhaustive testing process is made more difficult by contamination of the mummies' DNA over time and from chemicals used in the mummification process.

"[The DNA samples] are not just damaged because they are really old," Corthals said.

"They are also damaged because of the process of mummification. Ironically, what preserves the mummies best for their appearance destroys the DNA."

Several queens of the 18th dynasty, which lasted from 1550 to 1069 B.C. and preceded Tutankhamun's reign, have yet to be identified.

These include Kiya, who was likely Tut's mother and thus would share his mitochondrial DNA.

The queens Nefertiti, Tut's father's primary wife, and Tiye, Tut's paternal grandmother, have also not been found.

Mislabeled King

Scientists will study the male mummy on a hunch that it belongs to Thutmose I, who ruled from 1504 to 1492 B.C. and was the father of Queen Hatshepsut.

A mummy on display in the Egyptian Museum is labeled as Thutmose I, but recent tests revealed that the body is misidentified, Hawass noted.

"We found the mummy in the museum died at the age of 30, and Thutmose I died at the age of 50," he said. "He is not a royal mummy."

In 2007 Corthals and the Egyptian scientists conducted tests on a female mummy that is believed to be that of Hatshepsut.

The scientists will compare DNA from that mummy to the one recently found, but they note that making a connection will be hard because Thutmose I's family line is dubious.

His father is unknown and his mother was called Seniseneb, which was a common name during her time.

Inscriptions indicate that Thutmose I married his sister Ahmose, who was likely named after the first pharaoh of the 18th dynasty. But her exact parentage is also in doubt.

"It's not always clear who's in the family tree," Corthals said. "You may be testing who you think is the mother, but it might not be the mother at all."

In general, Corthals added, results from testing ancient DNA are not always certain.

"In the best of cases you can be only sure of a maximum … if you are really lucky of 90 percent [with mitochondrial DNA], but that's about it," Corthals said.

"There are to date no published studies that have successfully retrieved and compared ancient nuclear DNA from Egyptian mummies for the purpose of interfamily lineage."

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