What all can you find out from DNA anyway?

One way to think about how it works is book copying as an analogy. In fact, copies of books are related this way too.Let's say you have a hand copied book somewhere in Eastern Europe. As in the real world scribes can be very good copiests but also not precisely perfect.If our book is copied a lot then some of the copies are bound to have errors in them. If those copies are then copied at some other place the errors will be copied too and, often, new ones added. If this continues you can see that it will be possible to construct a relationship between the book copies.You might not be sure of which is the original but if you pick a copy as a starting point you can judge which is the next made from it. You infer this because the next copy will have the fewest errors from your assumed orginalYou will see that one error will appear in a whole series of copies but not in another bunch of copies. From that you can infer which copies are from one book and which from another.It isn't, of course, a perfect analogy since the copies only each have one "parent". I guess you could say that sometimes a book is copied half from one copy and half from another.From this you'll get a whole bunch of subgroups and branches just like with the DNA.

Remember? You have errors, I have errors we all have errors. The DNA copying mechanism is just like our hypothetical (and real) copiests. Very, very good but imperfect. It is difficult when you have to be told the same thing multiple times.What the things like "2% south Asian ancestry" are saying (though now we might start to step out to where I am not an expert) is that we see copies (you and I) that have errors that are much more common (so appear to have originated) in that location.That is where the book copying analogy has to be made more complex because all most all the time books don't have two parents and so can't bring in small amounts of other lines of decent.I find it very awesome to think (I got the national geographic sequencing done) that there was an individual in central Asia about 40,000 years ago that is a direct Y-chromosome ancestor of me. Of course, they had to be somewhere and there are gillions of them but the DNA thing somehow makes it more right there and real.The fact that we can read our ancestral history like this is amazing to me. It keeps getting better and more detailed to.