I just ran across this article, which I believe someone had mentioned previously by reference to an article that talked about it. I am a bit of a math nerd so reading the actual article and its modeling assumptions is quite interesting.
It is amazing to think that the most recent common ancestor of ALL human beings may have lived as late as 2000 years ago. Perhaps more surprising is the fact that all people who lived just 2000 or 3000 years before that are either (1) the ancestors of EVERYONE on earth today; or (2) have no descendants living today.
http://tedlab.mit.edu/~dr/Papers/Rohde-MRCA-two.pdf
I suppose we should not be surprised that we are finding so many common ancetors among ourselves 200 or 300 years back.
Most Recent Common Ancestor Article
Arturo:
That was a great article, but I have to admit I scrolled down past the statistical math charts and formulas and read the end part which was fascinating. Thanks for sharing.
PS: I love math, but this was really heavy stuff
Genetic Mapping in Mexico
Maureen,
I am glad that you liked the article. If you look on page 26 of the article you will see there is a map showing what percent of the DNA of a randomly selected Mexican "sim" (simulated person) in 2000 was from what country (square geographical division) 5000 years earlier.
It is interesting to see that the concentration is in Europe and North Africa and only one "country" in the Americas shows more than 0.1 percent. In fact two "countries" in Spain show percentages of more than 10 percent.
This is very contradictory to recent wide-scale DNA sampling that was done in Mexico by the Instituto Nacional de Medicina Genómica.
http://www.eluniversal.com.mx/nacion/149089.html
In fact, that study shows that the genes of the Mexican population as a whole are the result of mixing of more than 35 distinctly identified genetic strains originating in places as far as Europe, Asia and Africa. However, 65% of the genetic material is of strains originating in Mexico, or basically Amerindian.
Of course the chart from Rohde's article is explicitly of a "random" Mexican and that random Mexican could easily be the descendant of a recent immigrant from Spain who happened to have a "bit" of Amerindian blood in him but then he would not be very representative of the population as a whole.
Ancestry and Importance of in Medicine
Dear Arturo:
I finally had a moment to sit down and review page 29 in the Most Recent Common Ancestry and ancestry in medicine. Just wanted to say thanks for pointing out the page on the percentages with that nifty color-coded map and the other medical article. It is important to let everyone know how much your race or make-up thereof is to your medical history. Certain diseases and how the body is treated or reacts to different races or even sexes can mean the difference of life or death. This may be the single most important reason to know your family history. I even have a database in my genealogy software that calculates what percentage of people died from what cause and also the percentage of ages at death.
My husband had a medical emergency this winter. He does not look Hispanic, as he is light-skinned and the only thing that gives his nationality away is his name. He does look American Indian with high cheekbones and the slender facial features similar to what I have seen in the Navajo tribe. We knew through oral family history, that the family may have had Indian ancestors and recently some of the documents I have uncovered points to this. Anyway it was important that the medical personnel knew he was of Hispanic descent as it sometimes makes a difference in what medications which would have better effect or negative effects on the Hispanic population. This is true for all races, so maybe saying I am Irish-American is not such a bad idea after all! We had a debate on this a month or so ago and being just American or American and something else. Eventually we may well intermix, so that there will be only one race and thus no one can point fingers, do racial profiling and discrimination through race may be a thing of the past. Imagine...yes I am a 60's child, can you tell? By the looks of it though, the Hispanics have a jump on the Heinz 57 perfectly blended world!