Geneticist Dr Turi King and genealogist Professor Kevin Schürer give key evidence on the DNA testing
How did University of Leicester researchers go about testing the DNA evidence for Richard III?
Below is an account from the two experts who led the genetic analysis:
Dr Turi King, of the University of Leicester’s Department of Genetics and School of Archeology and Ancient History
Professor Kevin Schürer, Pro-Vice-Chancellor for Research and Enterprise and Centre of English Local History
The aim of our part of the project is to use DNA evidence to help identify the skeletal remains found at the Grey Friars site: does the DNA analysis corroborate the archaeological evidence and point to these being the remains of Richard III?
While it might be possible to obtain DNA from the skeletal remains, that would be all well and good, but useless without a known relative to compare the DNA to. Given the issues in obtaining permission to exhume the remains of contemporary relatives of Richard III, let alone the difficulties in retrieving DNA from ancient remains, this would not be the ideal way to go. A modern day relative would at least make building one half of the puzzle much easier. Fortunately, John Ashdown-Hill had been researching the family tree of Richard III and identified such a modern-day relative, in the form of Joy Ibsen.
Hypothetically, if the DNA from Joy Ibsen - and that of her son Michael Ibsen - does not match the skeletal remains, then this could be due to the fact that either (a) the skeleton is not that of Richard, or (b) they are not true direct descendents of Richard's mother Cecile Neville. Because of this potential uncertainty Prof Schürer has worked with other recognised genealogical experts to:
· independently verify and document the lineage between Richard's mother and Joy Ibsen;
· establish, if possible, a second maternal line of descent in order to cross-correlate this with the Ibsen CHA and that of the skeleton, and thereby provide added weight to any match or mis-match;
· identify living direct male, paternal line, descendents willing to provide DNA samples so that these might also be compared.
Any direct female line descendent related to Richard III should share Richard III's mitochondrial DNA type, passed from mother to daughter down through the generations. This is important for two reasons.
1. After we die, the usual mechanisms which keep our DNA intact stop working and so our DNA degrades: not only is there not much DNA left but it is broken down into smaller and smaller pieces. Our DNA can be divided into two different types: nuclear DNA which is found in the nucleus of the cell (there is only one copy of this per cell and we get half of it from our mother and the other half from our father) and mitochondrial DNA which is found outside the nucleus and of which there are hundreds to thousands of copies in each of our cells. So if there is any DNA left in the skeletal remains, it is most likely to be mitochondrial DNA.
2. We inherit our mitochondrial DNA from our mothers (through the egg). Mothers pass it down to all of their children, male or female, but only girls will pass it on. Both Richard and his siblings would therefore, all have the same mitochondrial DNA. Any living female line descendant of Anne of York, Duchess of Exeter (Richard's sister) therefore should share the same mitochondrial DNA type as Richard.
In addition, there is another strand of DNA evidence that can be brought to bear on the DNA analysis of the skeletal remains. This is using a piece of our nuclear DNA known as the Y chromosome. The Y chromosome carries on it the gene which determines maleness and so is only passed down through the male line. For this reason we have included living male-line descendents in our search of potential DNA donors as well.
Joy Ibsen sadly passed away a few years ago, but she passed on her mitochondrial DNA to each of her children. Michael Ibsen has very kindly given a sample of his DNA for our research project. This descent line has been verified to our best ability. In addition, after journeying down several blind alleys, we have fortunately discovered a second living maternal line descendent. This previously unknown second line has been checked and verified. The person in question has kindly consented to take part in our research, but does not wish to be named or identified, and we fully respect these wishes. The first step then was to determine if the two female line relatives shared the same mitochondrial DNA sequences. The analysis showed that these two individuals shared the same relatively rare mitochondrial DNA sequence.
Having found these individuals, the second part of the puzzle involved the ancient DNA analysis of the skeletal remains. The first step was to see if it was even possible to retrieve ancient DNA from Grey Friars skeleton. DNA breaks down over time and how quickly this happens is very dependent on the burial conditions. So even though the remains appeared to be in relatively good condition, I still couldn't be certain that I would be able to retrieve DNA from them. Therefore, we were extremely pleased to find that we could obtain a DNA sample from the skeletal remains.
Finally, the DNA sequence obtained from the Grey Friars skeletal remains was compared with the two maternal line relatives of Richard III. We were very excited to find that there is a DNA match between the maternal DNA from the family of Richard the Third and the skeletal remains we found at the Greyfriars dig.
Despite this exciting find, we should not forget the male line. A number of the men identified as descendents of Edward III through his son John of Gaunt (who would both have shared the same y chromosome as Richard III) have been kind enough to donate their DNA to our project. For the reasons given above it is significantly harder to obtain Y chromosome data from skeletal remains than mitochondrial DNA. As such this side of the work is still on-going, and may indeed prove inconclusive, but we are hopeful that, if it's possible to conduct a full analysis, it will provide a complete picture on both the male and female lines.
Professor Kevin Schürer said: “Clearly the archaeological evidence is highly significant. Yet placed alongside the DNA analyses it enables us to provide a measurable and highly reliable picture of the identity of the skeleton. This is critically under-pinned by the identification of all important second maternal line descendant which enables the DNA evidence to be triangulated.”
Dr Turi King said: “Like a forensic case, the DNA evidence must be assessed alongside the other evidence. Here the results of the archaeological and osteological analysis, combined with the genealogical and genetic evidence make for a strong and compelling case that these are indeed the remains of Richard III.”