This is an interesting article that uses simulated data to show graphically the difference between being genetically related vs. being genealogically related to a particular ancestor on your tree. From these simulations based on the inheritance property of autosomal DNA, you can observe that just within a few generations, the DNA of many of our ancestors is not represented in our current genome. Ancestors that were not able to pass autosomal DNA down to the present generation are represented by white blocks in the two graphs displayed. This phenomenon is pretty simple to explain. Each of us received basically 50% of our parents DNA. This immediately implies that the other half is lost unless they have more children and therefore a greater chance to pass additional segments of their DNA to the next generation. As we go back one more generation, that of our grandparents, randomness becomes a player in the equation and although statistically we average 25% of each of our grandparents DNA, the reality can show as much as 50% and as little as zero of a single grandparent's DNA. Mom and dad received 50% from each of their parents and therefore, they could have given us more DNA from one and less from the other. Going back a few more generations and more and more of your ancestors will not be represented genetically in your genome, although they were real people that are part of your family tree. These charts are based on simulations going back 11 generations. As the author explains it, just 20 generations ago, you would have had over one million ancestors. I want to add that 30 generations ago, approximately 750 years ago, or around the year 1250AD, each person alive today would have had more than one billion potential ancestors. If we think about Book of Mormon genetics and genealogy, Lehi and his family arriving to the American double continent 2600 years ago, or approximately 100 generations ago, would most likely be on every Native American pedigree chart and therefore be genealogically related to all those who have American pre-Columbian roots, but what is the likelihood that some of these individuals DNA would have survived until today?
Last year I received an invite to attend the Paleoamerican Odyssey conference that was held last week in Santa Fe, New Mexico. I declined knowing that it would have been difficult to find the necessary funding for yet another trip across the ocean this year. However, my good friend and colleague Dr. Alessandro Achilli from the University of Perugia (Italy) was able to go and wrote me immediately after attending the presentation where these results were shared. Now I really wished I would have gone!
The study that will come out in the prestigious journal NATURE shortly (as of today it is in press), describes the genetic analysis of a 24,000 year old skeleton found in Siberia. The complete genome was sequenced, including the paternally inherited Y chromosome and the maternally inherited mitochondrial DNA. The results were not quite what was to be expected. The young boy DNA showed no relationship to Easter Asians, but 1/3 of the genome in common with Native American populations and the rest with Europeans. Even the Y chromosome and mitochondrial DNA look European as they belong to haplogroups R and U respectively. The report from SCIENCE included the following comment from the leading researcher:
"The finding suggests that about a third of the ancestry of today's Native Americans can be traced to western Eurasia, with the
other two-thirds coming from eastern Asia, according to a talk at [the meeting "Paleoamerican Odyssey" in Santa Fe, NM on 16–20 October 2013] by ancient DNA expert Eske Willerslev of the University of Copenhagen. It also implies that traces of European ancestry previously detected in modern Native Americans do not come solely from mixing with European colonists, as most scientists had assumed, but have much deeper roots."
It is obvious that these data and findings will have major implications with regard to our understanding of Native American origins and colonization events. Moreover, it opens a lot more questions on a topic that for so many was already closed. For sure, there is so much more to learn about how and when the ancestors of Native Americans arrived to the Western Hemisphere. Although the DNA in this particular study refers to a very ancient specimen, the presence of European DNA in the Americas that predates the arrival of Europeans within the last 500 years poses some serious new consideration with regard to be able to discern any sort of Old World DNA in the Americas from the time of the first arrivals all the way through the millennia to our days. Can European DNA found in modern and ancient Native Americans be immediately dismissed as being for sure post-Columbian? Can we discern European DNA introgression in the America's gene pool from 20,000 years ago, 10,000 years ago, 3,000 years ago, or 1,000 years ago?
Native American genetics got all of a sudden a lot more exciting! It will be interesting to see what the future will bring.
Recently, the National Geographic's Genographic Project launched a new DNA test kit called GENO 2.0. It is an autosomal DNA test that covers very specific nuclear SNPs providing information about the history of our genes including a survey of our paternal line (Y chromosome), maternal line (mitochondrial DNA), and the deep ancestry written in the autosomes. It will link our DNA to the history of humankind as it started in Africa tens of thousands of years ago, all the way to the present time. I just ordered my own test, even though they won't be shipped until the end of October. This test will also compare genes between humans and apes, and even Neandertals, looking for surviving rare genetic links between our species and our closest relatives in the evolutionary tree.
National Geographic has a strong pro-evolution agenda, which continues to stimulates all sort of interesting thoughts in religious arenas about harmonizing the biblical creation account with evidence (particular genetic evidence) from science pointing to evolution (something that I have also speculated about in the past). Interestingly, just today, someone in a forum that does not like LDS beliefs mentioned me in a dissatisfied manner stating that "an LDS scientist speculates if those in the past were even human." Believe it or not, I don't think I am the first one that postulated that there were hominids more than 6,000 years ago, but I am flattered if someone would think so.
Here is a video by the Genographic Project introducing the new test.