Yep, we are headed into the bio century. In this brave new world a basic level of genetic literacy will be essential. That was a problem for me because I couldn’t tell one gene from another. But recently I discovered that the quickest route from the theory of genetics to the practice of it is to inspect my own genes. And the best motivator and context for that is that old fussy hobby of genealogy.
I have near zero interest in the path-names of my ancestors (and with a common surname like mine, near zero chance of unravelling it) but the puzzle of deep ancestors turns out to be a fantastic way to get comfortable with the sprawling vocabulary, concepts and techniques of genetics. You plumb your own genes for clues about your ancestry and in the process all genes become less strange.
About half a dozen companies offer a paid service to test your genes, taken from cells in the cheek, and provide a rough analysis of where you fall in the 100,000-year migration of humans across the globe. These outfits only sequence a very few points in your DNA, called markers. In general the more markers they check, the better. If you are willing, you can then submit your genetic marker results to the rapidly growing database of other folks who have tested their DNA. Some databases (and testing) specialize in African-Americans, some in Native Americans, and some try for a more general catch. All are quickly adding more markers, more sophistication, more crosslinking of results. In short, this is a fabulously fast-moving frontier that obeys the law of increasing returns: the more people that join, the more valuable and attractive it becomes for others to join.
It is also pretty geeky. Whereas traditional genealogy is nearly literary, steeped in anecdotes, names, and human drama; this new craft of genetic genealogy or “genetealogy” is primarily numerical: it is a flood of statistics, databases, algorithms, and the stuff of computer science. For better or worse it is also a ferociously technical, heavily quantifiable, gnarly hobby, and the early adopters are sprinting ahead rapidly. In fact so much is happening so fast in personal genetealogy that it is quite easy for almost anyone to become the world’s expert in a particular domain.
So how do you get started?
The easiest way to launch into the world of ancestral DNA is to enroll in The Genographic Project. This innovative program, run by National Geographic and IBM, will test your DNA with 12 markers (a decent benchmark in 2005). In addition you’ll get a great National Geographic map of genetic geography and a fantastic National Geographic documentary (The Journey of Man: A Genetic Odyssey) on our deep genetic roots and early human migration on this planet. This informative film, full of surprising news, is based on the work of Spencer Wells, who is both innovative scientist and enthusiastic host. He and crew scour the world for indigenous people with deep roots in one place, asking for samples of DNA to test, in order to piece together our “big family” genetic tree. The best parts are when they return with results and we see the diverse ways in which people and tribes react to the news of what science says about their arrival and relations. When you join The Genographic Project you fund this tree. A portion of the $100 fee for your test goes to Wells’s and other’s work, and you get your own DNA tested (anonymously) and the results in a form which you can share with others if you are inclined to. Since the fee is similar to what a commercial service would charge, it’s the way to go. You can graduate to more comprehensive and specialized testing as you progress.
But as helpful as the Genographic supporting material is, you’ll need a master guide to help you decipher the meaning of genes. By far the best orientation to this exploding universe is the new book Trace Your Roots with DNA. Written for avid family-tree fans, this is a great layperson’s introduction to personal DNA testing. It illuminates the complexities of such concepts as haplogroups, snips, alleles, mtDNA, and diminishing genetic relationships — all crucial genetic knowledge even if you are not into genealogy. If you ARE into family roots, this book is will provide you with tons of concrete advice on how to persuade relatives to get tested, where to post your results, and how to correlate genes with traditional genealogical research.
The authors are smart. They realize that news in this area will appear first online and only slowly migrate to paper books or magazines. They wisely direct you to preferred websites throughout their chapters. But their book offers a comprehensive overview of a frontier that no website currently offers. It is a wonderful portal to this coming century.
My son gets his cheek swabbed for DNA
But for now, you have all you will need to know if you grasp one fact: Y chromosome tests cannot prove that you share a particular common ancestor with another person, only that you share a common ancestor at some point.
There are move than 1,000 genes on the X chromosome, while the count of the Y chromosome in the year 2003 stands at just a fraction of that: 27. The genes on the X chromosome have little or nothing to do with sexual characteristics. They cover a broad range of structure and function, much like any of the autosomes.
The Y chromosome acts like a switch — if it is present, the baby will be a male. Genes restricted to the Y chromosome could hardly be essential for life and health, else the female of the species would disappear. Classical genetics has never identified any traits or diseases linked to the Y chromosome, so there is no need to fear that sharing DNA results will impact the ability to obtain health insurance.?
How often will two random Smiths match each other just by accident?
Just as surnames can be very common or very rare, haplotypes are found in different frequencies. In the database at www.yhrd.org, which has more than 24,000 records tested at nine markers, the single most frequent haplotype occurs in less than 3 percent of the population, so even that could not be called common in the absolute sense. Many haplotypes occur just once — more than 40 percent of the records, in fact. Every time a new set of data is added to the database, novel haplotypes are discovered.
Haplotype diversity can be quantified. The chance that two men chosen at random will match each other on all nine markers is less than two in a thousand. You can rule out a lot of false trails that way, and if two Smiths match, it’s probably not just a coincidence.
Adding more markers increases the diversity: Some of the men who match on nine markers will differ on a 10th marker.
We’re not going to sugarcoat it. Talking strangers into handing over their DNA — and hopefully, some money — is not the easiest of tasks. Presumably, it will become easier over time as genetic genealogy becomes as widely known as traditional research. At least then, those you contact will know that this is a normal activity that everyday human beings do with some regularity, and there will no longer be a need to educate people about the very existence of this kind of testing. But it’s best to prepare as if the person you’re about to call, write, or e-mail has never heard of genetealogy.
You can recruit people in two ways — by finding them or by making it easier for them to find you. We refer to the detective work associated with seeking out appropriate candidates as “reverse genealogy” since it usually involves tracing lines from the past to the present. Traditionally, we’re trained to start with ourselves and work back through the generations, but conducting a DNA project often requires the reverse. You may, for instance, be trying to find possible descendants of a German immigrant who came to Pennsylvania in the 1700s.
Please don’t make the mistake of testing in the hope of stumbling onto something interesting! In the future, when large numbers of people have been tested and accessible DNA databases are exploding with samples, the odds will improve that a random person could get tested and discover something interesting, such as a surprise match with a stranger. But we’re not quite there yet.