The Book About Human Dispersion I’ve Been Waiting For

… I was going to put, “… I’ve been waiting for all my life,” but it hasn’t been quite that long.

[T]he scientific community selected father-son pairs (or other male relatives of known genealogy) and sequenced their Y chromosome DNA. Then they counted the number of differences between the relatives. The number of Y chromosome DNA differences between them revealed how many copying errors occurred each generation. These differences told them how fast the Y chromosome clock ticked.

One of the first studies to measure the error rate was published in 2009. Two Chinese men of a known genealogical relationship going back to the 1800s had their Y chromosome DNA sequences determined. The resultant rate of copying errors was slow. It fit the existence of a “Y chromosome Adam” (the ancestor of all living men) about 200,000 years ago. In 2015, a study of hundreds of Icelandic men produced the same result.

So far, these results would leave the mainstream time scale as is.

However, due to financial and time constraints, these earlier studies were based on low quality DNA sequence. Then, in 2015, another research group compared father and son Y chromosome DNA sequences. This time, they used high quality methods. The result was a copying error rate that was much faster than the previous, lower quality studies: “The number of [father-son Y chromosome] differences was approximately 10-fold higher than the expected number … considering the range of published [Y chromosome copying mistake] rates.”

In fact, the data from this study implied that “Y chromosome Adam” lived just a few thousand years ago.

What was the mainstream scientific community to do? Oddly, they filtered their results, removing data that contradicted the 200,000-year timescale. They did so until the Y chromosome copying error rate matched their expectations.

In 2017, researchers compared the DNA sequences between 50 parent-offspring trios — i.e., they obtained DNA from father, mother, and child. Again, they did so by using high quality DNA sequencing methods. The researchers published detailed analyses of the copying error rate in these people. But conspicuously absent from their published results was a statement on the father-son Y chromosome copying error rate. Why?
From the raw data that did make it into their published study, a potential answer emerged. From this raw data, the father-son Y chromosome DNA copying error rate could be extracted. The results were consistent with the 2015 high-quality study. The 2017 Y chromosome copying error rate again implied that “Y chromosome Adam” existed about 4,500 years ago.

Traced, pp. 67 – 68

Jeanson, the author of this book, is a geneticist who works for Answers in Genesis. In this book, written for the lay person, he explains the study of genetics and its often counter-intuitive results. For example, early in the book he covers how, if all of your ancestors were unrelated to each other, by the time you go back about a thousand years you have to have had more great-grandparents than the population of the world at the time. Obviously that can’t be right, so in the deeps of the past, you must have had cousins or second cousins marrying each other. Also early in the book, he walks us through a simple thought/mathematics experiment to show how a minority population moving into a new area could make their genes the majority in that area after several generations by dint of simply having a few more children per family than the native population. This has actually happened in Europe with a Central Asian population that apparently came to Western Europe fleeing the Mongols.

Having oriented us and laid some foundational principles, Jeanson moves on to looking at specific branches of the human family tree as it has been reconstructed through geneticists looking at Y chromosome data. Using this data, we can “see” historical events like the population collapse that happened in the Americas in the few centuries after the arrival of Columbus; the massive people movements out of Central Asia in response to the Mongols; and the dispersion of certain haplogroups from East Africa into the rest of Africa in response to the Muslim expansion. Going deeper in the family tree, we can reconstruct the movement of certain haplogroups: for example, one group that started in Central Asia, split, and moved into India and into Europe, without meeting up again. Jeanson has a method, which he explains, to convert conventional dating for these events to his young-earth dates. In some cases, historical records like the ones mentioned above corroborate his method. If you look at the pages of his book end-on, the middle third of them are thick, high-quality, glossy paper. These are the diagrams, illustrations, and numerous maps to which Jeanson is constantly referring his reader. It really is important to be able to reference these in order to follow his arguments, so that you can visualize geographic dispersion and understand the different branches on the human family tree. (Being named by scientists, the branches have names like R1a and R1b, so it is really helpful to have a visual, where they are distinguished by different colors, to help you keep them all straight.)

Everyone likes to imaginatively trace the footsteps of their ancestors, but this book is a special treat for me. I am the kind of person who can get story ideas just from staring hard at a map. Give me a multigenerational migration story to go with it, and I’m in my element. This gets even more so when you start trying to use it to peer into the deep past. Bearing in mind that the world population was much smaller in past ages than it is now, when we look at these branches of haplogroups we are, in most cases, not seeing entire nations as we would now conceive of them. We are “seeing” clans, maybe in some cases individual families.

Traced is a real gift to people like me who want to write novels about early human dispersion. Of course, Jeanson is a good enough scientist to tell us that it is not the final word. Some haplogroups have been identified, but the sample size has been small. There are probably more out there, waiting to find their places on the big family tree. There are probably also haplogroups that have been completely wiped out, that will never be found no matter how many currently living men we sample.

8 thoughts on “The Book About Human Dispersion I’ve Been Waiting For

  1. I’m researching my next trilogy, Savage Land, based 75,000 years ago, about the time of the genetic bottleneck where man almost disappeared. I haven’t yet figured out what caused the bottleneck (not the Toba Eruption I originally blamed). Maybe this book can clear it up.

    I’m very excited to now be in a time period when mtDNA can guide my characters, that marker humans get through the mother than extends back a 100,000 years.

    Checking out this book…

    Liked by 1 person

    1. Glad I could help. Your books are written on a different timescale, of course, but perhaps you will still find some genetic gems.

      The thing that cracks me up about the bottleneck, is wondering where all the humans BEFORE the bottleneck came from …

      Liked by 1 person

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