Design of Life

British biomedical researcher Angelique Corthals thinks researchers (and their supporters at the Discovery Channel) who are trying to identify the remains of Egyptian pharaohs might as well be working for CBS’s fictional Cold Case drama, rather than in the lab.

In 2007 Corthals, a lecturer at the University of Manchester’s Centre for Biomedical Egyptology, told news media, "I think the people at the Discovery Channel went way too much 'CSI.'”

“They think you can pick up evidence at 2 p.m. and by 6 p.m. you get results,'' added Corthals, who has helped Egypt establish the DNA lab. But US-based Discovery Channel thinks otherwise, and has put considerable funds into the enterprise.

Thanks to a $5 million laboratory provided by Discovery in 2007, the Egyptian mummy identification team led by Zahi Hawass, Egypt’s Undersecretary of the State for the Giza Monuments, has facilities that have not available to researchers in Egypt before.

According to outfitter Applied Biosystems, a Discovery partner, the new lab is the "first laboratory in Egypt dedicated to testing ancient DNA samples."

Actually, the writers of Cold Case probably wouldn’t touch a script this old: using DNA testing to identify a 3,500 year old corpse found in the Valley of the Kings? But it’s a great way to learn about DNA - what it might and might not tell us, and why.

Is the Corpse really Thutmose I?

Researchers at the Egyptian Museum in Cairo are using DNA analysis and X-rays to identify a mummy from the Valley of the Kings at Luxor, which they think might be the famous Pharaoh Thutmose 1.

Thutmose I was a commoner who, on becoming pharaoh, distinguished himself by his building projects and military campaigns around 1500 B.C.

The search for Thutmose I began in earnest when the mummy, a male in his early thirties who was formerly identified as Thutmose, turned out to be an imposter.

How did Egyptologists know? The mummy previously on display died from an arrow wound to his chest and there is no record of Thutmose dying from such a wound. In any event, Thutmose I (approximately 1506 to 1493 BC), who was father to both Thutmose II and the female Pharaoh, Hatshepsut, is thought to have been well past 50 when he died.

While most events from the ancient world have not been recorded, the lives and deaths of pharaohs were recorded in considerable detail. Experts think that some unknown person was buried in Thutmose I's tomb and that the mummy of the real Thutmose I got lost a few thousand years ago, thanks to palace intrigue and rivalries.

While that sounds strange, it is not as strange as we might at first suppose. A constant threat for ancient royal families was grave robbers. Indeed, most tombs were looted in antiquity. Families, seeking peace for their dead, were known to bury someone else in the "official" tomb. One of Thutmose I's successors is thought to have removed him from his original tomb.

While the mummy of the real Thutmose I was widely believed to be lost forever, a sharp-eyed 19th century Egyptologist, Gaston Maspero, noticed that an anonymous mummy in Egypt’s vast collection, labelled #5283, looked like the mummies of Thutmose I’s son and grandson: Thutmose II and Thutmose III. Could he in fact be Thutmose I?

However, the matter was not pursued, so the other mummy remained on display at the Egyptian Museum for decades, labelled as Thutmose I.

Dr. Hawass is convinced that Maspero is right and that the mummy previously on display at The Egyptian Museum cannot be Thutmose I.

What Can DNA Testing Tell Us?

Dr. Hawass uses autosomal testing of nuclear DNA to identify ancient corpses. Although good nuclear DNA samples can be difficult to get from mummies, it information that cannot be found in mitochondrial DNA. In both humans and other mammals, nuclear DNA provides more genetic information than MtDNA.

We have two different types of DNA.

Nuclear DNA, found in the nucleus of the cell, consists of 46 chromosomes with three billion base pairs of DNA and approximately 25,000 genes. The mother provides an X chromosome to all her offspring. But the father may provide an X (the XX combination results in a daughter) or a Y (the XY combination results in a son).

So, the nuclear DNA, which includes an equal combination from both parents may give a fuller, more accurate, explanation. However the mitochondria or power plants of our cells, which lie outside the cell’s nucleus, each contain a copy of a loop of DNA with only about 16,569 base pairs, containing an estimated 37 genes.

Researchers believe that MtDNA is inherited mainly from the mother, not the father. But both parents contribute chromosomes to their offspring’s nuclear DNA. Therefore, nuclear DNA provides a clearer picture of both maternal and paternal inheritance than MtDNA.

The nuclear DNA of males proves even more interesting to researchers than that of females, because only males inherit the Y chromosome. Evidence suggests that the Y-chromosome may link all living human males back to a single Y-Adam (the most common recent male ancestor), whom geneticist and author Spencer Wells believes lived about 60,000 years ago.

So how do we know if the mummy is Thutmose I?

Scientists can try matching his DNA to the DNA of one of his royal relatives, such as a parent, child, or sibling, of whose identity they are pretty sure. Dr. Hawass has already performed tests on a mummy he believes is the daughter of Thutmose I, the famous female Pharaoh Hatshepsut.

On the Trail of Hatshepsut Too? In 2007, Dr. Hawass and his team performed CT scans and DNA analysis on a mummy believed to be Thutmose I’s daughter, Hateshepsut.

The CT scan showing a broken molar in the funerary box matched a gap in her mouth. In addition, DNA test results matched DNA from Hatshepsut with her grandmother Ahmose-Nefertari, which they believe confirms her identity.

While the team believes results of the CT scans and DNA analysis support their contention that they have found the ancient female pharaoh, others insist that the test results are inconclusive.

The DNA analysis results have not been replicated by an independent laboratory because (a) There is no independent laboratory in Egypt; and (b) Dr. Hawass will not allow DNA testing on Egyptian mummies to be conducted by non-Egyptians and does not allow mummies to be transported to labs outside Egypt.

So while the mummy his team examined in 2007 may indeed be Hatshepsut, his results remain unconfirmed.

While Dr. Hawass says he is looking for financial support to establish another laboratory in Egypt, no one has accepted his offer. So his results have not been replicated. And without independent verification of his results, his findings cannot be published in peer reviewed journals.

How Successful Can Hawass Be In Identifying Mummies?

There is no doubt that DNA analysis has become a useful tool in identifying modern humans. Genealogy researchers and police increasingly rely on DNA test results to confirm family relationships and solve crimes.

So, it’s not surprising that viewers of The Discovery Channel are intrigued by documentaries showing Hawass and his team of Egyptian researchers unveiling the identities of ancient pharaohs.

But DNA analysis is a complicated job that may not fit into shooting schedules and may not yield clear cut results. In the first place, getting accurate DNA results from mummies is no sure thing.

Over several thousand years, nuclear DNA deteriorates, so extracting usable samples is difficult. The mummification process itself may damage and destroy nuclear DNA.

Another complicating factor for modern sleuths is contamination of samples with modern cells the specimen comes in contact during transportation or even in the laboratory. In fact, some contamination probably occurred soon after the ancient royals died - in the workshops of the embalmers.

If Dr. Hawass and his team at the Egyptian Museum prove conclusively that the ancient mummies in their care are who they are believed to be, their accomplishments outstrip the imaginations of Cold Case screenwriters.

But, other scientists warn, that these results must be replicated by independent research teams in separate laboratories before the results can be confirmed. Peer review is also essential to giving the team’s work credibility. Otherwise, this work will remain more celebrated in the media than in the scientific community.