Adam, Eve and Population Genetics: A Reply to Dr. Richard Buggs (Part 1)

There are significant differences in levels of complexity too. Pidgins are rudimentary and not sufficient for all the communicative tasks of fully developed languages. But in certain contexts (often among displaced people from multiple groups, like when you had slavery in the Caribbean) where children grow up in an environment where family social bonds and generational continuity are disrupted, a local pidgin can evolve into a creole acquired by the children of speakers of diverse languages as their first language. But in those cases, new grammatical features emerge to accomplish the things speakers need to accomplish in order to communicate.

I don’t think this is true if they have never acquired a first language. Obviously you can’t run experiments, but there are several cases involving extreme abuse and neglect, like “Jeanie.” An infant brain needs exposure to language to develop the pathways that make language processing possible.

Here are some pretty good lecture notes I found, if you are interested:


Right, I was (not very clearly) trying to say that kids, given a pidgen, will automatically add levels of complexity and grammatical features to make it a real language. It’s not something that takes real long, and it’s not the adults making it happen or planning it.

Yes; I would not argue that someone in a ‘linguistic vacuum’ who didn’t have anybody to communicate with would naturally develop language. But if you put a cluster of kids together I think they would. The example of Nicaraguan Sign Language shows that kids can develop a language shockingly fast. The issue of infant development is tricky, and I’ve never claimed anything more than 50%+ “likely,” but two people inventing a language is far from impossible.

Thanks for the resource, will check it out!


It is hard to imagine! I get the feeling that we basically agree, but all these hypotheticals keep getting in the way. In the only example we have of language evolving from non-language, the process required many many thousands of years. I sincerely doubt it could be accomplished in one lifetime by two kids on an island. I also sincerely doubt we’ll have the opportunity to test the hypothesis, so who knows?

Basically all of the above. How do I know? I don’t! I’m just taking the experts’ word for it. Of course, maybe tomorrow they will change their minds, in which case I will change my mind, too. Haha. Here is one expert’s idea of what the evolution of grammar might have looked like:

  1. One-word stage – semantics with no syntax.
  2. 2-word stage – structured, but with none of the other features of language.
  3. Hierarchical structure, much like a basic phrase structure grammar, but without recursivity. (A language lacking subordinate clauses and other forms of embedding.)
  4. Recursive syntax. (Flexibility could precede or follow.)
  5. Fully modern grammar.

Each step corresponds to a functional communication system, although not as elaborate and rich as the modern one. They roughly resemble the stages of child language acquisition, where recursivity and flexibility are late additions.

“No one”. Really?

You got me! haha. But what we are discussing is the difference between “communication” and “language,” not the difference between humans and animals. No one in the thread (to the best of my memory, since I’m too lazy to look back through all the posts) brought that up until you said:

We can kick it around a bit, if you like. Since the imago Dei is not specifically defined in Scripture, traditional discussions of it usually came down to the question, “What makes us different from the animals?” The most common reply was reason/rationality, although other qualifications often were added, such as conscience, spirituality, free will, or personhood.

However, a more recent conception of the image of God is the royal/functional interpretation, such as we find in Middleton, Walton, Wright, and others. This interpretation views the image as mankind’s vocation, not an inborn quality. Thus, in this interpretation, the image of God has nothing to do with what makes us different from the animals, and everything to do with God’s intended purpose for mankind, a purpose that was rendered impossible for us to fulfill when we fell into sin.

I happen to subscribe to this latter interpretation. I’m curious how it has been received by Catholic theologians and scholars. Do you think it is compatible with Catholic doctrine?

Many thanks for this thoughtful answer!

Me too I subscribe the interpretation of the image as “mankind’s vocation” as you can see in Section 7.2 of this article.

This view is also strongly supported by Pope John Paul II and Karl Barth regarding Marriage as original vocation and sacrament.

And by Popes Benedict XVI and Francis regarding work as primeval divine vocation of mankind.

However in the thread on Original Sin’s Transmission new insights regarding the meaning of imago Dei in Scripture have been developed. For the sake of convenience in quoting I will answer this your comment there.

I didn’t see your reply, but I looked over your materials and the comments in that thread that specifically mentioned imago Dei or image of God, and I will reply to you there. This thread is already hard enough to follow, no thanks to my own off-topic meanderings.

Hi all,

I have just published another blog post on this issue at the Nature Ecology and Evolution Community here:

best wishes


Dear @DennisVenema

I am very grateful to you for your response to my original email and blog about the possibility of a bottleneck in the human lineage, and for the discussion that we have had in blogs and on this forum. Your work has helpfully highlighted an area of misunderstanding of current science that is probably shared by many, and it has been extremely informative to all of us to debate this issue and establish what current genomics does and does not show about past human population sizes. All of us have learned a great deal from this.

It is clear to me, as someone who has followed this debate closely and participated in it, that you (like me) now understand the field a lot better than you did before 2017. When you wrote Adam and the Genome you clearly believed that genomic evidence – from the case of the Tasmanian devils, from PSMC analyses, from the Tenesa et al study of linkage disequilibrium, and from allele counts – meant that it was almost impossible that humans had ever passed though a bottleneck of two since diverging from chimpanzees. You left your readers in no doubt about this.

In contrast, your more recent contributions on this forum show that you have now realised that the evidence that you cited in Adam and the Genome does not support this claim. You now realise that the studies you cite did not test a single-generation bottleneck of two. Your new understanding is clear to me as someone who has followed the discussion on this forum in detail, and weighed up what you have said and what you have not said, and what you have implied. Please do correct me if I have misunderstood you and I am drawing a wrong conclusion, as I have had to “read between the lines” in places to come to the conclusion that you realise that every one of these lines of evidence does not support the claim.

Assuming that I have understood you correctly, I think it is my responsibility to encourage you to make a clear public statement correcting what is erroneous in Adam and the Genome. I do this on behalf of readers of Adam and the Genome who will not have the time to read through the the debate on this forum (which is now much longer than chapter 3 of your book), but who are honestly seeking to understand what current science says and does not say about human population history. Not only will this be of service to your readers, but your reputation as reliable communicator of science will be enhanced by such a statement.

Yours sincerely,



I support what Richard has said. It is clear that when you wrote Adam and the Genome you were taking the published literature at its word, most of which said our population at the time of our split from chimps had an effective population size of 10,000. This seemed solid, as a number of different analyses yielded similar numbers. However, you made an extreme claim when you said that the certainity we could not have come from a bottleneck of two was as certain as heliocentricity.

Why this went wrong should be a lesson to all scientists: it is dangerous to extrapolate or over-interpret data, to go beyond what has been explicitly tested. No one had explicitly tested a bottleneck of two; it was the received knowledge that of course we couldn’t have come from two. Evolutionary theory said species were formed by progressive differentiation from an ancestral population. The claim was made that current genetic diversity could not be explained under standard assumptions if the species started from two. And that is true for recent origins. Standard assumptions won’t work for a young origin of two.Therefore it was not even worth examining, most assumed. But that conclusion was wrong, as we have seen.

Richard gave a very good summary at

Because the claim that we could not have come from two is wrong, and because that claim impacts the faith of many Christians, with corresponding doctrinal effects, it would be very helpful, even important, to set the record straight. This is not just a matter of a scientific dispute. All we are asking for is a public statement something like this: In a prolonged discussion with my colleagues it has become apparent that the claim that we had to originate from a population of 10,000 was never sufficiently or completely tested. Further analysis has indicated that it is possible that we could have come from a bottleneck of two.

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Hi Richard,

Thanks for your comments. Sorry I’ve been slow to respond.

I feel like I’ve gone over this before, but perhaps a recap would be in order.

In AatG I defend two claims - (1) that as our species, Homo sapiens (anatomically modern humans or AMHs), comes into being, we do so as a population. This is the “heliocentric” quote.

I also say that (2) the dip to ~10,000 seems to be the lowest our lineage experienced over the last 18 MY, based on the methods applied to date.

Both of these statements remain accurate. Our discussion has led us to agree that a 2-person bottleneck for the lineage leading to present-day humans is not plausible within the last 700,000 years or more. This is well before AMHs appear in the fossil record. So, point (1) stands, even if one might differ over just how “heliocentric” that certainty is.

Point (2) also stands. I’ve learned a bunch from our discussions - and I’m grateful for it! - but nothing we have uncovered provides any positive evidence for a 2-person bottleneck (or even a sub-~10,000 bottleneck) at any point over that timeframe. So, it still would seem that the ~10,000 number was the low point.

What we have established is that a very sudden bottleneck to 2 followed by exponential population growth might escape detection using current methods if it occurred before 700,000 years ago. That is interesting, but it does not change the points I made in the book. It still seems that ~10,000 was the low point based on current methods. In order to say that those methods might have missed the real 2-person bottleneck event, I have asked you (or others) to propose how such an event might have taken place.

Unless I’ve missed it - and I might have - I have not seen you propose any mechanism for a precipitous drop to 2 followed by exponential population growth. I don’t see this as plausible. @Swamidass gave it a go earlier, but that showed the difficulties. It can’t reasonably be genetic isolation of a population, since this is happening in Africa/Eurasia, and there is no way to geographically isolate populations on that landmass (the only way to assure genetic isolation). So, it would have to be an event that (a) kills off all but 2, but then somehow also allows for exponential growth immediately thereafter.

That’s not biologically plausible. At least, not to me, nor to any biologist I’ve discussed it with (except for @Swamidass, perhaps). Perhaps you have a model in mind to explain it that I am missing?

In other words, if what you are proposing is not biologically plausible I don’t see a pressing need to address it.

Now, if I was writing AatG today, I would include a discussion of this conversation, and what we’ve learned from it, to be sure. What I would also do, however, is discuss why I don’t find the “sudden catastrophic bottleneck to 2 followed by explosive exponential growth” hypothesis to be compelling.


… And now for something completely different:

Another thing that I have been meaning to ask for a long time in this conversation is this. Several years ago, you were widely quoted by the Discovery Institute and other ID sources as claiming that the identity of the human and chimpanzee genomes was around 70. It seems your original article on the subject is no longer online, but here’s how the DI quoted it at length:

Do you still think that humans and chimpanzees are around 70% identical at the DNA level? If so, why? If not, why not? Seeing as this is @glipsnort 's area of expertise, he might also be interested in your thoughts. I’ve been meaning to ask you this for months, and I keep forgetting to do so.


6 posts were merged into an existing topic: Discussion with Richard Buggs about chimp DNA

This claim is not substantiated by evidence. It requires an equivocation between Homo sapiens and “all our ancestors.” This is an example of the ecological fallacy.

The fact of the matter is we know that Homo sapiens dip down (backward time) to zero, so that obviously goes down below 10,000. Your heliocentric claim is transparently false.

You have missed it. That is a caricature of the argument and what is required for a genetic bottleneck. Someday we can press that argument, but its not worth it now.

More importantly, this is not related to your prior claim above, which is clearly not substantiated by evidence, and precisely false.

I confess to not having followed this discussion very closely. I thought around 500,000 years was the agreed limit – what are you basing the 700,000 years on? (Just curious.) Obviously, all of these numbers are somewhat mushy. If you accept the estimated time of 700,000 years for the sapiens/Neanderthal split, then that’s your limit, of course.

Not exactly my area; I was an author of the chimpanzee genome paper, but my contribution was in modeling selection, not in the sequence comparison. On the other hand, I am pretty familiar with the paper, and it’s safe to say that the quoted text is completely wrong. Similar claims have been repeatedly introduced into Wikipedia, where they have have had to be weeded out.

Short summary of the actual comparison:
2700 million base pairs (out of a total of roughly 3100 million bp) of the chimpanzee genome was sequenced well enough to be compared. That is the portion we can say something about. Of that 2700 million, 2400 million could be aligned to the human genome. This portion is the basis for the conclusion that 1.23% of sites in shared DNA differ by a single-base substitution, and that another ~1.5% was unique to each genome. (Based on these numbers the most reasonable single statement of overall similarity is that approximately 97.3% of the human genome is identical to the chimpanzee genome.)

The remaining 300 million base pairs of chimp DNA was sequenced but was not compared. 240 million bp were left out because they aligned to multiple places in the human genome. Much of this (I don’t know exactly how much) was the result of badly assembled chimp DNA, while some may represent genuine duplications in the human lineage. Another 90 million bp didn’t align to human at all; again, most of this was probably garbage of various kinds – badly assembled chimp DNA, parts of the human genome that hadn’t been assembled, etc.


No, we don’t know that. We know that there were once zero Homo sapiens, but that is not the same as saying that Hs “dipped down” to some specified bottleneck size, or to zero. The former is a statement about the characteristic of the population, while the latter is a statement about the population size. Two quite different statements.

I missed it too,


I know. Let’s grab a bear :bear: in Boston at the ASA meeting and hash it out. I’ll buy the first round for you =).

[:blush: Silly @BradKramer adds a :bear:, obviously I meant a :beer: ]

That is just an example of how we know the population genetics data does not tell us how many homo sapiens are around. It all comes down to how we define “homo sapiens”.

Regardless, this is all a red herring any ways (perhaps even intentionally), as there is no good reason to link “human” to Homo sapien. That is an example of eisegesis and concordism. “Human” in theology is not a scientific concept.

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I try to avoid grabbing bears – the results are always unpredictable and often painful. (Also, there are surprisingly few bears in Boston.)

I’m not currently planning on going to the ASA meeting, other than the science panel, but I’m sure we can arrange something.

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Other than the Bruins, that is.


You’re correct in your guess - the human / (Neanderthal - Denisovans common ancestor) split at ~ 700KYA. There’s also the fact that that Denisovans genome has some parts that seem to be around 1MY old, but that’s more up for debate.

I just don’t find the sudden bottleneck to two compelling either. For multiple reasons: 1. Hominins have always been pretty widespread so what kind of event can cause a severe bottleneck of two? What kind of natural disaster? Now I guess you could argue the event happened to a local population and that population dipped to two and then they outlived the other populations and didn’t reproduce with them. Which leads me to my second issue
2. If it happened to a local population what in the world could keep them isolated from the other populations? Like I said hominins moved around.
3. It seems the prior probability of a population dipping to two and not going extinct would be very low. And these two individuals would have to be male and female and at the right age to reproduce. A 40 year female and an infant aren’t going to do you much good.
4. I also have theological concerns

It’s an interesting idea but I don’t find it compelling at all.


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