The Barton Historical Society administrates a DNA project for male Bartons to get their Y-chromosome haplotyped. If you don't know what that means, allow me to put my geneticist hat on and attempt an explanation...

DNA explained


external image 615px-DNA_Structure%2BKey%2BLabelled.pn_NoBB.png
DNA, the famous long double-helical molecule (right; image from Wikipedia), is the recipe book for making all the proteins in your body. Some of those proteins are little more than building blocks. Many others are more like little atomic-scale robots that make or move or manage other things... and generally do most of the bustling that makes up Life. Some of those proteins even work together to copy the DNA and pass the recipe book down from parent cell to child cell, so that Life's little lessons - about what works and what doesn't work - don't go to waste if one cell, or one whole person, breaks.

DNA molecules are very long and very thin, and just like a paper book they can get unwieldy if too large. For this reason we have multiple volumes of it: separate DNA molecules that curl up like twisted string into knotty structures called chromosomes. A single set of human chromosomes has 23 of them.

However almost every cell in your body contains two sets of chromosomes, one set from your mother and one set from your father. But the set from your father - for example - isn't actually the same as his chromosomes, because he - like you - has two sets, one from each of his parents. No, the set that you've inherited from him was a brand new edition, that was freshly shuffled together from his two sets prior to being sent on its way in a sperm.

Now when two sets of DNA - two sets of chromosomes - are shuffled together like this it's not completely random. All going well, each chromosome is only going to get shuffled with its counterpart from the other set. These two different editions are mostly the same, but it's the modest differences between them that produce the modest differences between brothers and sisters. They are quite literally lined up alongside each other and parts are swapped over, usually (hopefully) without messing up the order of the pages (so to speak).

Each of your father's sperms carried its own newly remixed version of his (parents') DNA, but each of those versions were made from the same source material and are probably much more similar to each other than they would be to the chromosomes of somebody who is only very distantly related. (Obviously: for "father's sperms" you could substitute "mother's eggs" and this would still be case).

The difference between males and females has to do with two particularly special chromosomes, the X and the Y. Normally, if both your sets of chromosomes have an X chromosome, then you are a female. But if one of your sets has the short stubby Y chromosome, you are a male.

In the process of making eggs in a female, two X chromosomes can be lined up and mixed up just like any other chromosome. But in the process of making sperms in a male, the X and the Y are too different to line up and mix up (apart from some little bits at the end, but don't worry about that for now). So after all the other chromosomes have done their shuffle, the X and Y will normally go on their way basically unchanged. If the X sperm gets to the egg and pairs with a mother's X, it'll be a girl. If the Y sperm gets there first, it'll be a boy.

That makes the Y chromosome a little bit special. It (mostly) doesn't get shuffled from one generation to the next, so the only differences that creep in down the generations are little copying errors and that sort of thing. Leaving those aside for the moment, if you are a normal male, your Y chromosome will be virtually the same as the one that your father's father's father's father's father's father had. (And so on). In most countries, the same happens to be true for surnames as well, so Y chromosomes and surnames tend to be passed down together. In a perfect world (free of romantic infidelity!) I should have more-or-less the exact same Y chromosome as a distant cousin who has inherited the Barton name from the same males as me. Whatever differences occur will be down to rare copying errors


Y-DNA testing explained


DNA is basically a string of four different units that we can think of simply as four different letters (G, C, A & T). The protein recipes (genes) are written only in these letters. Scientists have become extraordinarily good at reading DNA sequences, faster, more accurately and more cheaply than ever before. Indeed improvements in this field are leaving even Moore's famous Law in the dust. But for the purposes of genealogy, reading every one of ~60 million letters of each of two whole Y chromosomes, so as to compare them, was and still is a bit of an overkill, particularly since, even with two hugely distant relatives, most of the letters will be exactly the same.

Scientists learned that some parts of DNA were more likely to be different between individuals than others. Either because they were less crucial bits (more 'expendable' and so safer for a cell to make mistakes while copying them) or because they were the molecular equivalent of tongue-twisters (inherently harder to copy correctly, so much more prone to changing while being copied). Or indeed both. These useful distinctive bits of DNA are called 'markers' because they mark variation. Scientists already knew how to pick out and copy particular little bits of DNA, so it wasn't too hard to find a set of markers that they could quickly copy and easily visualize, thus creating a 'genetic fingerprint' that was as representative of an individual as a normal fingerprint was. Or as representative of an individual chromosome.

Your chance of having one fingerprint that is the same as someone else's is fairly low. But, as any detective knows, the chance of you and somebody else having ten identical fingerprints is very very low. In just the same way, comparing 67 genetic markers is much more accurate and distinctive to an individual, or to a Y chromosome, than comparing only 37. But obviously you can only compare markers if you've fingerprinted them in both individuals. At each marker you will find a particular variant that may be the same or different between individuals.

external image D1S80Demo.gif
A simple genetic fingerprint (image from Wikipedia). Each column is a marker (apart from the 'ruler' columns on either side), and each of the bands in each column is a variant that travels a different distance through an electrophoresis gel due to being a different size in each set of chromosomes. If this is done with the unique Y chromosome, there will be only one band in each column.

When the lab work is over, genetic fingerprints look a bit like barcodes, but as patterns of lines they're not so easy for people to read or share. So you can write a fingerprint down using some sort of code, for instance writing a different code number for each marker, then giving each of those a different number for each variant of that marker:

e.g.
Marker:
390
19
391
385a
426
388
439
389
392
456
454
464
448
437
455
421
432
312
328
Variant:
12
8
6
21
13
16
13
11
9
2
23
15
16
10
4
24
12
10
9

In Y-chromosome DNA (Y-DNA) testing the resulting code is called a Y-DNA haplotype. It often helps the human eye to compare different haplotypes if the different variants are colour-coded.

In practise, Y-DNA haplotypes can be categorized into different 'haplogroups' that correspond to separate ancestors (ignoring those occasional copying errors). With some clever mathematics, the copying errors can to some extent be used like a clock to measure very roughly how many generations ago a common male ancestor lived.


Family Tree DNA Ltd.


The company that the Barton Historical Society uses for its DNA project is called Family Tree DNA. They offer simple tests using only 12 markers (which tell you relatively little except your Y-chromosome 'ethnicity'), or using 37 markers (the typical test), or 67 or even 111 markers (for the best certainty and accuracy). You have to pay for your own test, although the Barton Historical Society does occasionally offer to part-sponsor tests that they think might be particularly informative. They did this for me, though alas I let them down!

The Barton project results are tabulated on this page. My own haplotype can be found under the ID G-66. There are no reliable matches at present, but the project has had very few UK participants. If a match ever does crop up, I should be automatically contacted. If you are interested in having your own test done, contact Terry Barton through the Barton Historical Society website.


Oxford Ancestors Ltd.


Some years ago my father had his Y-DNA tested by a different company in the UK: Oxford Ancestors.

[WORK IN PROGRESS]