DNA, Ancestry, and the Book of Mormon

The following post is intended to add to the essay about the Book of Mormon and DNA studies [1]. Some of what I wrote is covered in that article but the rest is supplemental. My hope is that this article offers additional information about the complexities of DNA and genealogy.

There are various comments and criticisms of the Book of Mormon based on what DNA supposedly does or does not show with some people essentially saying whole genome analyses show there is no Lehite DNA in the Americas. This post addresses that issue but also hopefully offers broader insights into family history and genetics. It will likely change over time as I continue to refine and add to it.

Generations and numbers

Each generation is about 25 years on average. In 1,000 years, this works out to approximately 40 generations. To calculate the number of direct line ancestors someone has, we can start at the individual and work backwards: one person has two parents, four grandparents, eight great-grandparents, and so on. This works out to a simple exponential formula: 2n, where n = the number of generations. So in 40 generations (or about 1000 years), someone should have 240 direct line ancestors. That works out to roughly 1.1 trillion (1.0995116 x 1012) 40th generation ancestors for each person alive today. That is about 10 times the total number of humans estimated to have ever lived over hundreds of thousands or millions of years [2]. About 1,000 years ago, various estimates put the world population at 250 to 300 million people [3]. That is much less than the estimated one trillion people 1,000 years ago, which means for the mathematics to work out people have common ancestors in their family trees.

“Branches of your family tree don’t consistently diverge,” [Dr. Adam] Rutherford says. Instead “they begin to loop back into each other.” As a result, many of your ancestors occupy multiple slots in your family tree. For example, “your great-great-great-great-great-grandmother might have also been your great-great-great-great-aunt,” he explains [4].

In an analysis of a large family tree including 13 million verified individuals [5], a team of scientists made a number of discoveries that support the previous quote. One of those was that (for at least those of European ancestry), from about 1650 to 1850, people on average married 4th cousins. By 1950 it had changed to 7th cousins on average. Some people married closer cousins and others married people who were “unrelated” (but everyone is related, as we’ll see). Humans share about 99.9% of their DNA. 1st cousins share about 12.5% of DNA, 2nd cousins share about 3% of DNA, and 3rd or more distant cousins <1% [6]. This means that there is no genetic risk above the general population for abnormalities in the children of 3rd cousins. In practice there is essentially no risk for 2nd cousins and only a slightly elevated risk of adverse genetic outcomes in the children of 1st cousins.

For much of history (if we can extrapolate from the research based largely on European ancestry), people had children with relatives. It is still the case, just at a more extended distance. This is why family trees “loop back on each other” [4].

Ancestry, genes, and relationships

Scientists estimate the dates for the hypothetical individuals who are called “Mitochondrial Eve” and “Y-chromosomal Adam” at about 200,000 and 237,000 to 581,000 years ago, respectively [7]. However, our most recent common ancestor mathematically must be more recent than that. Humans only need to go back a few thousand years to all be related to one another.

Here’s the abstract of an article with the calculations:

One model, designed for simplicity and theoretical insight, yields explicit mathematical results through a probabilistic analysis. A more elaborate second model, designed to capture historical population dynamics in a more realistic way, is analysed computationally through Monte Carlo simulations. These analyses suggest that the genealogies of all living humans overlap in remarkable ways in the recent past. In particular, the [most recent common ancestor (MRCA)] of all present-day humans lived just a few thousand years ago in these models. Moreover, among all individuals living more than just a few thousand years earlier than the MRCA, each present-day human has exactly the same set of genealogical ancestors. (emphasis added, [8]).

The interpretation of this is that every person on earth has a common ancestor who lived around 1000 BC. The following quote from an article geared towards lay audiences references that paper and expands on it.

“The consequence of humanity being “incredibly inbred” is that we are all related much more closely than our intuition suggests, Rutherford says. Take, for instance, the last person from whom everyone on the planet today is descended. In 2004 mathematical modeling and computer simulations by a group of statisticians led by Douglas Rohde, then at the Massachusetts Institute of Technology, indicated that our most recent common ancestor probably lived no earlier than 1400 B.C. and possibly as recently as A.D. 55. In the time of Egypt’s Queen Nefertiti, someone from whom we are all descended was likely alive somewhere in the world.

“Go back a bit further, and you reach a date when our family trees share not just one ancestor in common but every ancestor in common. At this date, called the genetic isopoint, the family trees of any two people on the earth now, no matter how distantly related they seem, trace back to the same set of individuals. “If you were alive at the genetic isopoint, then you are the ancestor of either everyone alive today or no one alive today,” Rutherford says. Humans left Africa and began dispersing throughout the world at least 120,000 years ago, but the genetic isopoint occurred much more recently—somewhere between 5300 and 2200 B.C., according to Rohde’s calculations.”[4; see also 8]

This means that some thousands of years ago, anyone alive who has any living descendants is related to everyone today (“If you were alive at the genetic isopoint, then you are the ancestor of either everyone alive today or no one alive today”). Biological genetic evidence doesn’t really allow us to pinpoint when our common ancestors lived but based on the mathematics of genetics and ancestry, it’s clear people are all related to each other much more recently than hundreds of thousands of years ago.

The genetic isopoint has implications for the scriptural “Adam” and “Eve”. It also applies to the “House of Israel” (or tribes of Israel, including the lost 10 tribes) and how they can be scattered among all nations. It has implications for the Lamanites and modern Native Americans.

Let’s first look at Europe. Using these same estimates, everyone who has European ancestry is related to every European in about the 10th century AD who has any living descendants. This is so short because it’s a relatively constrained geographical area but as quoted above, it only takes up to a few more thousand years to get back to common ancestors for the entire world. How this works is that someone like Charlemagne (or other concurrent royalty), from whom many people try to claim descendancy, is the ancestor of every living person with European ancestry. Documenting that tie into Charlemagne’s line is the challenge – most people just don’t have records that reliably go that far back in time (and most people claiming they do are mistaken). However, because there are no records does not mean there is no relation.

Below is a summary of the “ancestry” of my DNA. It’s most similar to people from northern and north central Europe. That matches the family history records but it is also misleading. Based on the analyses in the Rohde, Olson, and Chang (2004) article [8] and others, if we could go back 1000 years, I am related to everyone in Europe who currently has any living descendants. One of the issues will be discussed later but it has to do with disappearing DNA from ancestors.

DNA matched ancestry for the author

Now let’s jump over to the Americas. Applying this to Lehi means that if he has any living descendants (e.g., among modern Native Americans), then all people today with Native American ancestry are related to him, based on how many generations have passed (about 104) and based on the mathematics and genetics referenced above. This does not make Lehi the chief ancestor of Native Americans but it does make him (and Ishmael, Zoram, Mulek, the Jaredites, etc.) among the ancestors. As far as we know, the “primary” ancestors of Native Americans came via Asia. Again, because of how the mathematics of ancestors works out, all Native Americans can literally be “Lamanites”, just like all people in the world can literally be related to Abraham, Isaac, and Jacob (there are possibly some people who are not but the mathematics of genetics indicates the vast majority of people should be).

Genetic Testing of Ancestry

Because of the random reshuffling of genes in each successive generation, some of your ancestors contribute disproportionately to your genome, while others contribute nothing at all. According to calculations by geneticist Graham Coop of the University of California, Davis, you carry genes from fewer than half of your forebears from 11 generations back [4].

That people can be related but share no DNA is called genetic drift or what I call disappearing DNA. Some estimates show that up to 10% of 3rd cousins share no DNA [9]. No DNA test can find matches for missing DNA, although mathematical models for estimating relatedness, especially when looking multi-generationally, are possible. What DNA testing cannot do reliably is show relationships beyond 5th or 6th cousins [9]. Even after 2nd cousins it can be difficult [10].

This means that even if we knew what genetic signature to look for (what was Lehi’s DNA?), it’s possible that many, even most, Native Americans today, while descended from him, would have no DNA from him. They are descendants but might not look like it genetically. This is not unique in the Americas, this is true for all of us. We do not have genetic material from most of our ancestors (fewer than half, 11 generations back and beyond that even less) so whole lines of ancestors will not show up in our DNA. That is one reason why my DNA ancestry map is localized largely to northern and north central Europe. The other is because finding DNA matches beyond 5th – 6th cousins becomes difficult to not possible with current technology.

Now a comment about availability of DNA samples. Some of what I have been referencing about DNA and ancestry was covered in book called “A Brief History of Everyone Who Ever Lived” by the geneticist Adam Rutherford. At one point in the book he mentions, in passing, Native American DNA studies: “The genetics of Native Americans are poorly understood, and there are no specific tribal markers in DNA” [11]. There is a lot of historical and current distrust by many Native Americans over DNA and other medically-related research (based in part on some egregious abuses in the past). As time goes on, scientists will be able to collect more and more representative DNA samples. This will require careful and thoughtful research. It requires outreach and support to historically medically marginalized and abused populations. Doing so will start to provide more complete pictures of DNA. However, the issue of disappearing DNA (genetic drift) and the fact that everyone today is related to the same people who lived some thousands of years ago, make DNA work incomplete until it can demonstrate what the mathematics of ancestry shows. Humans share about 99.9% of their DNA but we do not have the technology to verify the mathematical models showing that everyone is descended from the same people who lived several thousand years ago.

Conclusion

The Book of Mormon peoples existed. If any living Native American is related to any of them, how the mathematics and genetics work, it is accurate to say, “All/most Native Americans are descendants of Lamanites”. They are descendants of many other people too — principally, those who crossed over from Asia tens of thousands of years ago.

Based on the existing limited DNA data and the other factors addressed above, making any sort of conclusion (e.g., “no Israelite DNA in Native Americans”), is short-sighted. What this means is existing Native American DNA studies cannot be used to “prove” or “disprove” anything about the Book of Mormon, ancestry, and DNA.

Finally, DNA and ancestry is much more complex than most people realize. This fact is particularly condemning of people who try to use DNA for racist purposes (e.g., claim superiority of one “race” over another). As Dr. Rutherford pointed out:

Ancestry is complex and poorly understood. Indigeneity is similarly complex and requires nuance and thought. Admixture is the norm, migration is continuous, and no people is pure [12].

Dr. Adam Rutherford, Twitter, Dec. 16, 2020

Again, as useful as DNA studies can be, trying to understand ancestry is complicated and everyone alive today is related to everyone alive several thousands of years ago [13]. Add to this the fact that we do not share DNA with many of our direct line ancestors, which means that ancient “Israelite” DNA might never show up in Native Americans even with direct “Lamanite” ancestry.

It also means that we, as the scriptures and modern prophets teach us, are all one family. We are God’s children. He loves us and wants us to love Him and all of His other children. If we can recognize that we are all related, hopefully we will start to treat one another with more kindness, patience, understanding, and love.

References

  1. https://www.churchofjesuschrist.org/study/manual/gospel-topics-essays/book-of-mormon-and-dna-studies?lang=eng
  2. Kaneda, Toshiko, and Carl HaubHow Many People Have Ever Lived on Earth? Population Reference Bureau 05/18/2021 https://www.prb.org/articles/how-many-people-have-ever-lived-on-earth/
  3. https://www.census.gov/data/tables/time-series/demo/international-programs/historical-est-worldpop.html
  4. https://www.scientificamerican.com/article/humans-are-all-more-closely-related-than-we-commonly-think/
  5. Kaplanis, Joanna et al. “Quantitative analysis of population-scale family trees with millions of relatives.” Science (New York, N.Y.) vol. 360,6385 (2018): 171-175. doi:10.1126/science.aam9309
  6. https://isogg.org/wiki/Autosomal_DNA_statistics
  7. See a summary here:  https://en.wikipedia.org/wiki/Most_recent_common_ancestor
  8. Rohde DL, Olson S, Chang JT. Modelling the recent common ancestry of all living humans. Nature. 2004;431(7008):562-566. doi:10.1038/nature02842
  9. https://isogg.org/wiki/Autosomal_DNA_statistics
  10. M. Sun, N.A. Sheehan, et al., “On the Use of Dense SNP Marker Data for the Identification of Distant Relative Pairs.” Theoretical Population Biology, 107 (February 2016): 14-25. DOI: https://doi.org/10.1016/j.tpb.2015.10.002
  11. Rutherford, Adam. A Brief History of Everyone Who Ever Lived: The Human Story Retold Through Our Genes. United States: The Experiment, 2017, p. 155.
  12. https://twitter.com/adamrutherford/status/1339196867129843714
  13. https://www.theguardian.com/books/2020/jan/30/how-to-argue-with-a-racist-adam-rutherford-review (note that there is an inaccuracy in that article about the date of the isopoint, which should be closer to 3,400 BC than 3,400 years ago)

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