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Sunday, 27 July 2014

The Great DNA Surprise


During the last couple of months I have been repeatedly asked to respond to claims by some Mormons that recent human genomics research offers support for the belief that Native Americans have Jewish ancestors. The paper causing the excitement , written by Maanasa Raghavan and others and entitled “Upper Palaeolithic Siberian Genome Reveals Dual Ancestry of Native Americans,” was published in the Jan. 2nd volume of Nature (published online Nov. 20, 2013)one of the most prestigious of scientific journals. The paper would have gone unnoticed by Mormons had a National Geographic journalist not sensationalised it with the following hyperbole.


"Great Surprise"—Native Americans Have West Eurasian Origins.

Oldest human genome reveals less of an East Asian ancestry than thought.
Nearly one-third of Native American genes come from west Eurasian people linked to the
 Middle East and Europe, rather than entirely from East Asians as previously thought, according to a newly sequenced genome.

Not surprisingly, Mormons only interested in headlines have seized upon this research as conclusive proof that Native Americans have Middle Eastern, and thus potentially Jewish, DNA (1, 2, 3, 4). To be fair there are the odd exceptions who have suggested caution in interpreting the research as supporting the Book of Mormon. However, even President Newsroom cited Raghavan's research in the Church's official DNA essayclaiming it proves the picture isn't clear and challenges previous conclusions. In reality, the conclusions being challenged have nothing to do with recent Hebrew migrations and everything to do with major human migration events that took place over 30,000 years ago. There is absolutely nothing in the Raghavan research that supports the Book of Mormon or challenges the mainstream scientific views about the colonization of the New World. Native Americans are still essentially all descended from Asian ancestors. 


Putting the Research in Context 

Raghavan's research did not appear in a vacuum. It adds another detail to the broad scientific understanding of the timing and route our ancestors took as they colonised the globe. The common ancestors of all humans lived in sub-Saharan Africa. They began migrating "out of Africa" about 80,000 years ago and by about 50,000 years ago had colonized Western Asia, India and Southeast Asia and Australia (Fig.1). Eastern Asia was colonised by people derived from this southern migration event. By about 40,000 years ago people arrived in Europe and Central Asia via a northern route, finally reaching the Americas between 15 and 25,000 years ago.

Fig.1.   Major routes and timing of human colonisation of the world (Wellcome Trust, www.sanger.ac.uk

Scientists have found absolutely no evidence that we all descend from a single man and women (Adam and Eve) who lived on the earth about 6,000 years ago. This is simply not what happened. The volumes of evidence in support of the mainstream scientific views is vast and spans numerous disciplines. It is the truth and Mormons must face it. When the individual whose Raghavan's team studied was alive, humans had not even reached the Americas so it is difficult to comprehend how it tells us anything about mythical Jewish migrations in the last 3,000 years. 

Fig. 2.  Location of Raghavan's  Siberian sample


The 2014 Raghavan Study 

Raghavan's team isolated DNA from the bones of a 24,000-year-old individual and sequenced its entire genome. They then examined 156,000 DNA markers (SNPs) to reveal how closely related this individual is to hundreds of other people from contemporary populations (Fig. 3).   


Fig. 3.  Heat map of relatedness between the Siberian (MA-1) and individuals from numerous geographical locations around the world. The graded heat key on the left indicates to degree of relatedness with red indicating high relationship and black low relationship. (See Raghavan et al. 2014)

The major finding of the study is that the Siberian individual is not closely related to East Asians and much more closely related to Native Americans. This suggests that people who migrated from Western Asia into Siberia did not mix very much with Asian populations further east after they arrived. Consequently, when some of them migrated on to the Americas, they didn't carry many DNA markers found in East Asian populations.

Another way of describing the results of the study is shown in Fig. 5 below. All Eurasians and Native Americans descend from people who lived in West Asia (near modern day Afghanistan and Pakistan) about 50,000 years ago (see also Fig. 1.). These people carried with them large numbers of DNA markers that can be defined as West Asian. When the ancestors of the Siberians and Europeans/Middle Easterners migrated away from each other, both groups carried the same set of West Asian (blue) DNA markers with them. This is why the Siberian individual carried DNA markers also found in Europeans and Middle Easterners. They shared common ancestors about 15,000 years earlier (50,000 years ago).   

However, once they became separated from each other, each group began to accumulate DNA markers that were unique to each group. This is indicated by the green (Eur/ME) and purple (Siberian) shading on the tree (Fig. 5). 




Summary

Virtually all Eurasian and New World populations descend from populations that migrated out of Africa and colonised West Asia about 50,000 years ago. Eastern Asia is likely to have been first colonised by populations that split away from a southern migration through India that ended in Australia. The Raghavan study tells us that Siberians are mostly derived from people who migrated into Central Asia via a northern route that resulted in little admixture with Eastern Asian populations. The research paper is entirely focussed on very ancient migrations and tells us precisely nothing about the likelihood or occurrence of recent Jewish migrations to the New World as described in the Book of Mormon.