Tuesday, February 5, 2013

Richard the Third's DNA

Ever since I read Jacqueline Tey's short mystery The Daughter of Time, I've been a little bit obsessed with the last Plantagenet king of England, Richard III. May I recommend you read it too? A gripping story with absolutely no action--the whole thing takes place in the hospital room of a detective with a broken leg. Detective Grant, having nothing better to do, attempts to find the real Richard III through books his friends bring him.
Richard III, the evil hunchback, usurper of the throne, murderer of the two Little Princes in the Tower, shares a dark corner of history with Nero, Ivan the Terrible, and the Sheriff of Nottingham. That's history as written by the victors, in this case the Tudors and their scribes. Richard's death in the Battle of Bosworth Field in 1485, brought the saintly Tudors, such as Henry VIII, to the throne.

They've found Richard's bones! Not in Westminster Abbey with the other kings but under a parking lot in Leicester. Seems he died from a severe blow to the head and wasn't even afforded a coffin. His naked body was put on display to teach the English subjects a lesson. I'm not sure what that lesson was. Then they wrapped him in some cloth and buried him in the Church of the Grey Friars, which is now a parking lot.
They found a direct decendant of the king's sister living in Canada and have confirmed the relationship through mDNA. That's mitochondrial DNA. For those of you who may not understand why this evidence is definitive, let the old--ahem former--biology teacher explain it to you.
The DNA in the nucleus of your cells contains the instructions for making you you. Half from your mother, half from your father. One fourth is from your father's father and one-fourth from your father's mother. Trace it back for, say 10 generations, and only about 0.02 percent of the nuclear DNA you now carry came from your ten greats grandfather. Or your 10 greats grandmother. In other words, you are the product of about 5000 people who lived at the time of the American Revolution.
Richard III had no children, but no matter. They and their descendants would be useless for our purposes.
He did have a sister and his sister had children.
Mitochondria are tiny energy packs in cells but outside the nucleus. They have a special kind of DNA. With only a few genes, their DNA (mDNA) doesn't have nearly as much info as the nuclear DNA. Your mDNA came only from your mother. Her mDNA came from her mother. And so on. Why? Remember, a sperm is tiny. Nothing more than a half-pack of DNA with a tail. An egg is huge. It's a complete cell with mitochondria, ribosomes--the whole works, but only a half-pack of DNA. If the fortunate sperm and the egg do meet--two half-packs make a whole pack and the new individual has . . . but you already know.
What about the new individual's mDNA? It's exactly like his or her mother's. (Except for the occasional mutation) Men are dead ends for mDNA. Women who have children are forever, as long as their daughters keep having daughters.
So, when these bones were found, scientists went looking for a descendant of Richard's sister's daughter's daughter's daughter's . . . etc. They found a man in Canada whose mDNA (from his mother) filled the bill. Fortunately the English never throw anything away, especially records. They compared this man's mDNA with a little bit they extracted from the bones and--TA DA--it matched. Maybe not a perfect match but the number of mutations that would accumulate in 500 years is small compared to the total.

On a recent trip to London, I dropped by the National Portrait Gallery on Trafalgar Square and studied the best-known painting of Richard III (not the one you see here) No matter how long I looked, I couldn't see a villan. I saw a worried man. I hope historians will take another look him.

No comments:

Post a Comment