Jeanson's Method of Inferring Past Population Sizes

Well I’m thankful to @thoughtful for bringing this to our attention. I had missed this, and may just not have believed upfront he had done something this out there. I’m reminded of Poe’s law…


It does say the “entire tree” of humanity and “but also” region specific patterns

After I began to be curious about the scientific process behind Genesis 1, I took a detour into looking into Nimrod from Genesis 10:8-11. In just a few sentences, it gave me enough info to compare the first empire in recorded history, Akkadian empire with the one the Bible also lists as the first. I kept following the rabbit hole in Wikipedia and satisfied my own curiosity that every significant civilization left behind ruins or written records and that tools dated later were just from farmers at the same time. The details are fascinating, but you wouldn’t believe me. Anyway satisfied my own curiosity to not worry about the dating but look at details of the archaeological and written records for clues instead.

You really should worry about the dating, because that destroys Jeanson’s time scale. Aren’t you worried that you ignore everything except the data you find convenient to your preconceptions? That’s not a good way to determine if those preconceptions are correct.

I know, that’s what I said…

If I’m understanding it right, this is perhaps just a worldview problem. Jeanson has less than 200 generations for all humanity, so there would be very few branches that get cut off - like I said, most cultures prize having at least one son, probably many more.

Evolution has a constant population size for millennia, and there would be many branches that get cut off.

Would I be correct in framing it this way?

No. Even from a YEC worldview, Jeanson’s argument makes no sense. It is like arguing 1+1=3. That isn’t true, even if you are YEC.


Even if we were to grant the hypothetical scenario where no men ever died before having sons, his method still makes no sense. These are the paragraphs where Jeanson tries to justify using a sample of <350 men to reconstruct the last 3000 years of population size changes, but it’s just gibberish:

“Deeper consideration of the multiplicative nature of human population growth further refined this criterion. Mathematically, biblical population growth of males spanned about 9 orders of magnitude— growing from an initial population of 4 men (e.g., Noah, Shem, Ham, Japheth) to nearly 2 billion in 1975. Yet the high coverage dataset that I employed (Karmin et al. 2015) spanned only 2 orders of magnitude (i.e., less than 350 men were sampled). Mathematically, it would seem unlikely that a sample of a few hundred men in the present would permit access to the entire population history of the globe.
Instead, under the second criterion, we might have expected these datasets to capture the most recent 3,000 years of human population growth. For example, in 1000 B.C., the male population was already 25 million. By 1975, this number had grown by only 2 orders of magnitude—to nearly 2 billion. Since the Karmin et al. (2015) dataset represented men sampled in the present and, therefore, represented a look back in time at the population growth that led to these living males, we might have predicted this approach to capture population growth post-1000 B.C. Before 1000 B.C., population sizes would have grown by 7 orders of magnitude—too great a change to be detected by our methods. Thus, we might have expected pre-1000 B.C. population inferences to be a flat line—no branching events due to the multiplicative nature of human population growth.”


There’s actually historical evidence for this. China used to have a great many more family names than it does now. Family names pass through the male line, and most of them have now become extinct. And of course the Y chromosomes associated with those lines have also become extinct.


OK, I see he’s saying he employed a minimum value to capture this, but y’all would argue it still doesn’t pass the test?

"Before comparing these historical data to the population growth curves inferred from the Y chromosome, I added a correction factor to the historical data. My reasoning was as follows: Because Karmin et al. (2015) sampled living males, they effectively sampled the history of only those historical lineages that left survivors in the present. From historical records as well as from archaeology, it is well known that the last 3,000 years of human history record periodic population downturns and episodes of population stasis (i.e., see McEvedy and Jones 1978). Population downturns imply loss of Y chromosome lineages, due to death of male offspring or, simply, to failure to reproduce. Similarly, population stasis can lead to loss of lineages. For example, Biggar et al. (1999) contains an analysis of over 700,000 Danish families at population stasis (i.e., number of children born was equivalent to the sum of the number of fathers and mothers). Their results showed that 28% of fathers left no male offspring (see Table 1 of Biggar et al.). Thus, by sampling the historical male lineages that survived, no one using Karmin et al. (2015) data would ever be able derive a population growth event followed by a downturn. Rather, inferences derived from Karmin et al. (2015) data would simply depict the lineages that made it through the downturn.

Thus, to make the evaluation of my predictions more rigorous, I converted the known global population growth curves from Maddison (2001) and McEvedy and Jones (1978) into minimum population growth curves. Where historical stasis or downturn events occurred, I connected the growth curve data points at their minimum values. Practically, this resulting curve is a type of smoothed global population curve (Supplemental fig. 1; see also Supplemental table 6).

Yes it does not pass the test.

He took one curve of increasing numbers (the number of Y-chromosomal lineages), and claimed it was a population size estimate. This is equivalent to arguing 1+1=3.

He took another curve of numbers, of estimated population size in the past, derived assuming an ancient earth and ancient ancestors. This is equivalent to starting from the assumption of an old earth.

Then he applied several unwarranted modifications to each of the two curves, modifying the second into increasing numbers, until they somewhat aligned. This very much looks like manipulation of data, and it certainly is not a valid test.

Compare his work to this phenomenal work that recovers events from history using a standard population genetics model:

Don’t miss the excellent website here:

There is just no comparison favorable to Jeanson.

  1. They don’t resort to any 1+1=3 arguments.

  2. They are able to see genetic evidence of ONE HUNDRED events in history.

  3. They make their software available for any one to look at and reproduce.

  4. They, in 2014, use the whole genome, instead of just the Y-Chromosome, which Jeason falsely claims is impossible to use for this purpose.

For Jeanson to be right, he needs an explanation of how it was possible to line up, in the evolutionary timescale, 100 events with the genetic data. He doesn’t have one, of course.


Why do I need to be worried? I believe in Jesus. I already generally understand how the world works. If I die, and there’s no God, oops I was wrong. But I do believe in God, I know I need His grace. Origins are an interesting question, and I do consider the data and file it away as a question mark if I don’t know, but it matters little on the grand scheme of things for someone who has full confidence after testing their beliefs a lot.

You don’t need to worry about your faith, because it is rooted in Jesus. However, that should give you confidence to worry about Jeanson’s work specifically.


Does he do any work to demonstrate that this adjustment is sufficient? Not that I can see. His adjustment just crudely chops off the lumps in the historical population growth curve, as you can see in his supplementary figure 1 (black lines vs grey lines).


I wasn’t aware of this so I’ll have to take a look and see what they predict versus where he’s gone since I watched the videos.

Correct. And if I only believed in YEC because of his work, then my confidence should be lower in this as you’ve shown me. But I believed YEC is true before I came across this because, as I explained earlier, I think Jesus’ miracles pointed to His command over instantaneous creation as the Word of God.

What’s interesting to me, is that even if his work is sloppy, if YEC is true, it will “bear more fruit” at least historically than an evolutionary time scale. So here, it’s time will tell. I will definitely check out the link to see what they’ve got.


If you don’t care about any of this, why are we even talking?

Perhaps. But he doesn’t always use instantaneous creation, does he? So the question is when does he and when doesn’t he, and science can certainly help there. It’s clear from science that the universe, earth, and life are all much more than 6000 years old. So Jesus must not have used instantaneous creation for that.

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Disappointing. @thoughtful seemed to be someone who could put her ideological preconceptions aside and accept the assistance and explanations patiently provided by the scientists here, some of whom are world-renowned in this field. And hopefully that remains the case, but it’s looking a bit shaky now.

@swamidass’s comment is very much on point. It doesn’t say much for one’s faith if it cannot withstand accepting facts about physical reality that are beyond serious question.

Phew! I found it. :sweat_smile: I enjoyed the videos, but watching them again was a little bit boring when I’d rather watch quantum physics now. :joy: Anyway, it’s at 29:53 here

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I would differentiate between caring and worrying. I had post-partum anxiety twice. Counseling helped the most. I found out for myself after applying what I learned that worrying is about making idols, which has never helped me. “Caring” means I’m interested in the topics and enjoy researching it and learning more. So thank you for helping me do that.

I can’t think of an instance off the top of my head where Jesus didn’t do a miracle instanteously - besides the resurrection, and that fulfilled prophecy that he was buried 3 days. The point being that Jesus’ followers believed in the Genesis 1 story literally. And every time Jesus did a miracle, the gospels record they were astonished - what kind of man can do this? Is he sent by God? Is he Elijah back from the dead, as he also did lots of miracles and that seemed to fit a prophecy? It wasn’t until he rose from the dead that they realized He was God and was the Creator. The purpose of John 1 is to also make that clear.

So us saying 2000 years later that creation took a long time, feels to me like trying to fit a square peg in a round hole. Something or a lot of things don’t pass the smell test. The Bible literally read requires a lot of miracles…in the physics thread, I learned it’s the creation of light separately after time. That was cool to me to realize. It requires the miracle of a man only made from dust or particles, and his wife made from him. It also requires a miracle of the start of a global flood. Science can’t evaluate those miracles very well if everything appears to be running consistently.

Peter talks about this: 2 Peter 3:1-7
This is now the second letter that I am writing to you, beloved. In both of them I am stirring up your sincere mind by way of reminder, 2 that you should remember the predictions of the holy prophets and the commandment of the Lord and Savior through your apostles, 3 knowing this first of all, that scoffers will come in the last days with scoffing, following their own sinful desires. 4 They will say, “Where is the promise of his coming? For ever since the fathers fell asleep, all things are continuing as they were from the beginning of creation.” 5 For they deliberately overlook this fact, that the heavens existed long ago, and the earth was formed out of water and through water by the word of God, 6 and that by means of these the world that then existed was deluged with water and perished. 7 But by the same word the heavens and earth that now exist are stored up for fire, being kept until the day of judgment and destruction of the ungodly.

Please let him correct me if I’m wrong, but that wasn’t the point. If I’ve built my faith on a rock, that is Jesus, then there’s intellectual freedom to explore questions about which one has some of a lot of doubt. It doesn’t mean I MUST accept them. Would a scientist be willing to die for a scientific “fact” - that the world is exactly a certain number of billions of years old, give or take a few million? I doubt it. Should a Christian be willing to die for their belief in Jesus? Yes.