Posted by Kate Phizackerley on Tuesday, September 01, 2009

I've been reflecting on Keith Payne's comment in my previous post. I'm pretty confident now that a new tomb (KV64) has been found in the Valley of the Kings, probably dated to the last 30 years of the 18th Dynasty.

I'm a little less sanguine about DNA testing being used to compile a family tree. I'll try to do a DNA primer. In short for now though, the DNA everybody thinks of is the 23 pairs of chromosomes found in the nuclei of cells - nuclear DNA. One of each pair comes from the father and one from the mother - at random. Looking at them you can't say which chromosomes came from the father and which from the mother. If you have a detailed map of the father you could guess which came from the father and therefore, by deduction, which came from the mother. However in a family as inter-related as we believe the Egyptian royal family to have been, there's going to be high amounts of common DNA between the two parents. Combined with potentially poor samples after 3,500 years I doubt that's realistic.

The exception is a male Y chromosome. That has to have been inherited from the father.  Paternal inheritance is therefore usually established by looking at the Y chromosomes. It should be possible - if the samples are good enough - to build a picture of the male side of the royal family. (Assuming, of course, that illegitimacy wasn't an issue.)

We know however that the records of the parents of princesses and queens are less complete anyway. There isn't a female equivalent to the Y chromosome. Matrilineal descent is therefore usually determined by looking at mitochondrial DNA.

Mitochondrial DNA is ancient in origin - it goes back to when bacteria infiltrated single-celled organisms.  It resides in the outside of cells, not in the nucleus.  Whereas the DNA in the nucleus is densely packed and therefore somewhat protected, mitochondrial DNA is fragile and less likely to be well-preserved.  Because it sits in the mitochondria, it is passed through the egg, not via sperm which carry only nuclear DNA.  It is therefore passed from mother to offspring and is the key for determining matrilineal descent.

Unless the mitochondrial DNA is preserved, then the DNA from Tutankhamun and from the foetuses from KV62 will not directly identify the mother and certainly won't push back to Nefertiti who was (presumably) the foetuses' grandmother.  The project is groundbreaking so it is possible that mitochondrial DNA has been preserved and can be analysed, but personally I am not hopeful.

Similarly, the mummy of Queen Mutnodjmet is not ideal for determining Nefertiti.  It is thought that they were half-sisters and shared a father but not a mother.  While it is easy to show the relationship of male siblings using nuclear DNA, if one or more of them is female, there is no Y chromosome to compare. 

I suspect that the project will be revealing new findings for several years.  At the outset my prediction is that the initial results will be focused on the male line.  That is not without interest - the identity of Tutankhamun's father has been the subject of much speculation - but I don't believe in the first pass we will get definitive answers about his mother, or indeed the matrilineal line in general.

4 comments:

Keith Payne / Shemsu said...

I have read elsewhere that there was reason to doubt some of the excitement over the DNA testing of the Eighteenth Dynasty, but this is the first time it was really broken down in a way I could wrap my head around.

But as we all know, sometimes the hype goes front page and above the fold, while details and corrections are worked out on page 11, Section C!

To the degree that I have helped hype the DNA hype, there may be more of an element of passive-agressiveness there than I am willing to admit.. ;-)

Anonymous said...

Kate
You are getting Nefertiti and Cleopatra mixed up. Cleopatra and her sister had different mothers. There is no found evidence to link Nefertiti's sister to Horemheb's wife. A similar name is all that exists.
No one would say that Ay must have married Amenhotep's wife Queen Tiye just because both wives have the same name (spelt differently by authors to avoid confusion) but spelt the same way in ancient times.
I cannot help but think this is yet another way by Hawass to "prove" that Joane Fletcher was wrong in her identification of The Younger Lady as Nefertiti.
Jan

Kate Phizackerley said...

Jan

Opinion is divided on whether Queen Mutnodjmet was, or was not, Nefertiti's half-sister.

Kate

rymerster said...

I still think there's a possibility that Mutnodjmet was Nefertiti's sister and Horemheb's queen - we just haven't got conclusive evidence either way. There has to be a reason why Horemheb is regarded as the last of the 18th Dynasty and not the founder of the 19th (which he was, by appointing Ramesses I his heir). IF Mutnodjmet was Ay's daughter OR Nefertiti's sister (therefore posessing royal blood) it is possible that he married her to solidify his claim to the throne. We still need to learn more about the murky period surrounding the reign of Ay.

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