Thursday, February 19, 2009

DNA test

To celebrate the birthday of Charles Darwin, I finally decided to order a DNA test. As everybody knows, the results will reveal the particular species of monkey from which I descend, and the jungle in which my ancestors lived, maybe even the kind of trees in which they built their homes. Besides that, this DNA test will no doubt confirm that I have an exceptionally high level of extremely healthy and active intelligence genes, and that I was genetically endowed to be a really superior guy from every point of view. Based upon hard facts, the test will no doubt also explain scientifically (for those who were not already aware of this particular aspect of my being) why I've always had a terrific sensual effect upon beautiful women, a little like Julio Iglesias (but without the singing) or George Clooney (without the Nescafé ads). And I'll be getting all this great information sent to my doorstep, direct from Arizona, for no more than 120 euros.

Well, the results of the test might not be quite like that. So maybe I should set aside my wishful thinking and describe the DNA test in a more modest down-to-earth way.

[Click the logo to visit the Family Tree DNA website.]

I lost no time in choosing a company to carry out my test because, in the genealogical domain, there aren't really very many companies around. The laboratories that you hear of in the news—when scientists talk, say, about cracking the genome of Neanderthals or the possibility of cloning furry mammoths—are not concerned with the DNA of ordinary mortals such as you and me. Most of the high-profile companies that advertise their high-priced services in DNA analysis are medically-oriented, which means that they're capable of obtaining personal data about your genetic makeup that might just prevent your descendants, one of these days, from purchasing life insurance, finding a partner and procreating, or even getting certain jobs. Apart from that, though, it's great to know yourself better from a health viewpoint. As far as genealogy is concerned, most people seem to agree that the Arizona-based company called Family Tree DNA is the ideal door to knock on, because they propose an infrastructure enabling you to meet up with other individuals with comparable DNA profiles.

One of the first sobering things you learn, when you step into the domain of genealogical DNA tests, is that specialists refer to the precious molecular fragments used in their analyses as junk DNA. Now, this doesn't mean that they think your ancestors are trash. Even if a living prince were to use DNA testing to confirm that he descended from a long-dead king, this would be done by means of junk DNA. The adjective "junk" simply draws attention to the curious fact (well, it's curious for newcomers) that the fragments of the DNA double helix yielding the most information as far as family links are concerned lie outside the all-important sequences of genetic coding that determine what kind of hereditary makeup we have. Between the genes, in our lengthy strand of DNA, there's a vast quantity of chemical "noise" (to borrow the term used by communications engineers), which doesn't play any role in determining our inherited nature. Well, this junk part of our DNA reveals certain patterns that remain constant from a father to his sons. These patterns get copied in the Y-chromosome, found only in males. Consequently, if the DNA of two males happens to contain identical patterns of this kind, that means that their paternal ancestral lines reach back to a unique male individual.

What does this mean at a practical level? Let me give you an example. In an article written in August 2007 entitled Dorset ancestral anecdotes [display], I mentioned an old pump organ that I discovered (and actually played) in the village of Blandford.

The label on the instrument mentioned a William Skivington, proprietor of a local music shop.

The UK census of 1861 mentions this fellow and his family, and refers to him as a piano tuner. I'm surely a relative of this individual, who lived from 1827 to 1912, but I've not yet been able to determine our exact links. Now, let's imagine an unlikely discovery. Let's suppose that, inside the organ in the Blandford folk museum, we happened to find a trace of blood that had been left there long ago when William Skivington hit his thumb with a hammer while repairing the instrument. Normally, if this fellow were indeed a distant cousin of mine, we should find that junk DNA recovered from the spot of blood in the organ has the same markers as in my own DNA test.

OK? Well, that fictitious scenario does not in fact describe the usual way in which genealogical researchers go about using the results of DNA tests. Although this approach would be theoretically sound, we don't generally go around searching in pump organs or cemeteries for specimens of the blood of our supposed ancestors. I would be more interested in coming upon a fellow who's living today, let's say a certain Fred Skivington settled over in Canada, who is convinced—through sound documentary evidence—that he is a descendant of the Dorset piano-tuner William Skivington. In such a situation, if Fred's DNA markers coincided with mine, then this would reveal that I, too, am related to the William of Blandford.

I'm obliged to admit, though, that it would be very tempting to have an opportunity of fossicking around in some of the ancient tombs over in the village of Skeffington in Leicestershire. You never know what kind of junk you might dig up there...

1 comment:

  1. I really enjoy following your blog on Google Reader - but I always click through so I can see the wonderful photo in the header. I never know what you will be writing about although I'm aware of a number of your themes - atheism, Australia, where you live in France, family history, social issues (current and historical)- and find them all fascinating stuff.

    Keep it coming!