Geneticist Richard Buggs, Reader in Evolutionary Genomics at Queen Mary University of London, has just written an intriguing article in Nature: Ecology and Evolution (28 October 2017), titled, Adam and Eve: a tested hypothesis? Comments on a recent book chapter. It appears that Buggs is unpersuaded that science has ruled out Adam and Eve. He thinks it’s still theoretically possible that the human race once passed through a short, sharp population bottleneck of just two individuals, followed by exponential population growth. Buggs disagrees with the assessment of Christian biologist Dennis Venema, professor of biology at Trinity Western University in Langley, British Columbia, who forthrightly declared in chapter 3 of his 2017 book Adam and the Genome that it is scientifically impossible that the human lineage ever passed through a bottleneck of two, and we can be as certain about this fact as we are about the truth of heliocentrism.
Here’s Buggs’ take-down of the three methods employed by Venema to discredit the possibility of a single primal couple. As a layperson, I have to say it looks as if Buggs has done his homework:
Linkage disequilibrium within populations
…The methods assume that the populations at any given time point are at equilibrium and not expanding exponentially (the authors deliberately exclude the last 10,000 years from this analysis as they know that exponential population growth has occurred in this timeframe). It is hard to see how they could pick up on a short, sharp bottleneck even if one had happened. It would be nice to see this modelled, just to check.
PSMC method
…More recently, some simulations by a graduate student have shown that the PSMC method does not detect short, sharp bottlenecks, such as those caused by a pandemic or natural disaster. Thus I cannot see that PSMC analyses (many more of which have been done on human genomes since the original paper by Li and Durbin) can be cited as rigorously disproving a short, sharp bottleneck.
Incomplete lineage sorting
Venema makes an argument based on incomplete lineage sorting among humans, apes and gorillas, which gives a large estimated effective population size. This argument is not relevant if we are only interested in the human lineage (the occurrence of ILS does not require maintenance of large populations sizes in every lineage after speciation and so does not exclude a bottleneck in the exclusively human lineage).
Buggs adds:
We need to bear in mind that explosive population growth in humans has allowed many new mutations to rapidly accumulate in human populations (A. Keinan and A. G. Clark (2012) Science 336: 740-743). Hyper-variable loci like MHC genes or microsatellites have so many alleles that they seem to defy the idea of a single couple bottleneck until we consider that they have very rapid rates of evolution, and could have evolved very many alleles since a bottleneck.
In his conclusion, Buggs modestly refrains from claiming to have rebutted Venema’s arguments:
The question asked by my religious friends is different to the questions being asked in the studies discussed above. My religions (sic) friends are not asking me if it is probable that humans have ever passed through a bottleneck of two; they are asking me if it is possible. None of the studies above set out to explicitly test the hypothesis that humans could have passed through a single-couple bottleneck. This is what we need to nail this issue down…
If I am missing something, then I would very much like to know. Whilst this issue may seem trivial to many readers, for large numbers of religious believers in the world, this is a critical issue. Do they really face a binary choice between accepting mainstream science and believing that humans have, at some point in their history, all descended from a single couple? I am open to the possibility that they do face this dilemma, but I need more evidence before I am persuaded.
I would be interested to know what biologists think of Richard Buggs’ article. Is he right? Does science still leave open the possibility of Adam and Eve? Over to you.
J-Mac, to Joe:
Translation: It was rilly rilly fast, because Jesus.
vjtorley,
According to most christian teachings Adam and Eve were perfect, therefore they and their offspring should have had none or few mutations…
They apparently lived close to 1000 years, so their mutational rate must have been lower if any…
What do you think of her arguments? I don’t intend to argue by proxy.
Do you think any of that makes any sense at all? I don’t. Would you care to defend it?
J-Mac, to Vincent:
Right. So why did they sin? It doesn’t make sense.
John, to Vincent:
Vincent offered a half-hearted defense in an earlier thread:
Not very persuasive, and it didn’t stand up well to scrutiny, as you can see by reading the rest of that thread.
In body perfect but a disobedient spirit.One strike and they screwed up everything for the rest of humanity .
newton,
In which case they weren’t perfect after all. God screwed up. He’s responsible for the Fall.
Yes, but the evidence does not agree with the model of keeping it at 2!
Gee look at where the population suddenly popped up, about, hehe, 6000 years ago, not long before recorded history.
Rob Carter and Nathaniel Jeanson’s model then comes very well into play if we assume created heterozygosity.
http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway/understanding_environment/population_pollutionrev1.shtml
Thank you all for interacting with my Nature Ecology and Evolution Community blog, and thanks to Vincent Torley for posting here. Vincent kindly sent me a personal email pointing out this thread to me and asking me to specifically interact with comments made by Steve Schaffner and Joe Felsenstein. I will also comment on John Harshman’s comments as he is making the strongest case against a bottleneck of two, which was not mentioned explicitly by Dennis Venema in his book chapter.
First, I note that both Schaffner and Felsenstein agree with my point that the bottleneck hypothesis has not been directly tested.
Schaffner: “Buggs is right that existing tests have not been tested rigorously against an ancient Adam and Eve scenario. On the other hand, no one has shown that such a scenario would be undetectable by those tests either; it’s just not a scenario most geneticists are interested in.”
Felsenstein: “Most of the effort in analyzing these data has been to infer the past history of population size, rather than to make statements about A&E.”
Felsenstein goes further than this and suggests that it could never be entirely disproven: “If one poses the problem as whether we can absolutely certainly rule out A&E, that is asking for more than science can deliver. But if we ask whether it is made very improbable, that is not as hard to establish.”
Second, I note that neither of them are defending the PSMC argument, and Felsenstein implies that it is not necessarily reliable and new methods need to be developed
Felsenstein: “There are coalescent methods that use more information than PSMC, which only uses 2 haploid genomes at a time. Those methods need more development, but when they get it there will be more focused analyses.”
Thirdly, I note that no one so far has challenged my statements about the Tenesa at al paper based on linkage disequilibrium (I would welcome more comments on this paper).
Fourth, I need to respond to Schaffner’s comment: “The argument about total heterozygosity is a red herring. A tight but short bottleneck has a relatively modest effect on heterozygosity, but a dramatic effect on the distribution of allele frequencies. A bottleneck of two individuals eliminates all frequencies at less than 25% frequency, which is where the great majority of variants are.”
I don’t think it is a red herring, as (1) it is worth pointing out to the non-specialist that the results of a short bottleneck are far less devastating than a long one, where inbreeding would eventually eliminate all allelic variation; (2) during a bottleneck of two, most variability has to be carried by heterozygosity within the two individuals, so this is important; (3) because there are four DNA bases, two individuals can potentially carry all possible alleles at any given SNP locus. In response to his final sentence above, I note that it is the high frequency alleles in the human population that most require explanation in terms of ancestral variation, and those alleles at less than 25% frequency are also the ones most easily explained by recent mutation.
Fifth, I’m really glad to hear that Steve Schaffner has done some simulations. This is exactly what I think needs to be done to nail down this issue.
Schaffner: “I doubt anyone has ever made a formal test, but having played around with simulations I think an absolute minimum of several hundred thousand years would be required to generate something like the observed frequency spectrum for humans; half a million years is a more plausible lower bound… It’s not clear how many creationists are interested in a half million year old Adam anyway.”
I very much hope that Schaffner will write these up for publication. I agree with his final comment, but a creationist (in the conventional sense of the word) would not be concerned about this entire topic as it assumes common ancestry and creationism can have genetic diversity front-loaded into Eve’s ova anyway, thereby avoiding the whole issue of genetic diversity. I suspect many Christians, Jews and Muslims would be interested in the idea of a half million year old ancestral bottleneck of two.
Sixth, to come to John Harshman’s comments: John is making an argument from huge allelic diversity of HLA (human MHC) alleles and signatures of incomplete lineage sorting among these. This is the strongest argument being made in this thread against an ancestral bottleneck. Schaffner and Felsenstein have commented on this:
Schaffner (on HLA): Buggs is suggesting that some of the alleles shared between species could represent homoplasies, presumably as a result of similar selective pressures. How likely that is depends on how complex the alleles are.
Felsenstein: “Just saying that rates of mutation are high and so the pattern could occur is insufficient. One needs a more quantitative analysis with estimated mutation rates. HLA is a hard case for A&E — it would be even better to find more polymorphisms involving multiple haplotypes and put all that information together.”
I agree with both of these points. More work is needed to show in detail whether or not MHC diversity renders a bottleneck impossible. My major overaching point here would be that we need to look at genome-wide patterns of polymorphism to get a reliable picture of past effective population sizes. MHC loci are pretty exotic. Several studies show that they evolve fast and may be under sexual selection, pathogen-mediated selection, and frequency-dependent selection; they may also have heterozygote advantage (see e.g. http://rspb.royalsocietypublishing.org/content/277/1684/979). The maintenance of MHC polymorphism is still “an evolutionary puzzle” (https://www.nature.com/articles/ncomms1632). There is some evidence for convergent evolution of HLA genes (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1918223/, http://onlinelibrary.wiley.com/doi/10.1111/j.1600-065X.1999.tb01381.x/full, https://link.springer.com/article/10.1007/BF00189233, https://link.springer.com/article/10.1007%2Fs002510050028). If the whole case for large human ancestral population sizes rests on MHC loci, I think this is inadequate to prove the point, given our current state of knowledge on MHC evolution. As Felsenstein says “— it would be even better to find more polymorphisms involving multiple haplotypes and put all that information together.”
Richard Buggs,
Welcome to TSZ, Dr Buggs.
Considerably after recorded history starts. The first written texts are about 6,600 years ago. The discrepancy is well-described in this ancient account:
https://www.theonion.com/sumerians-look-on-in-confusion-as-god-creates-world-1819571221
Joe:
I love The Onion. 🙂
Note that I did not say that the PSMC results are unreliable. Just that more information is potentially available, which can be exploited with some more development of methods.
Also
I would advise against the use of the word “impossible”. In science we don’t ever get absolute certainty.
I’d like to thank Dr. Richard Buggs for dropping by, and for commenting on this thread. The take-away from this discussion is: “More work is needed to show in detail whether or not MHC diversity renders a bottleneck impossible.” Dr. Buggs doubts that this is the case, given the peculiar fproperties of MHC loci, and concludes: “If the whole case for large human ancestral population sizes rests on MHC loci, I think this is inadequate to prove the point, given our current state of knowledge on MHC evolution.”
Second, if the human race is descended from a single primal couple, it seems that this couple must have lived at least 500,000 years ago. That’s an interesting finding. The date roughly coincides with the time when the ancestors of Homo sapiens, Neandertal man and Denisovan man diverged. I note further that all of these species of human beings had 46 chromosomes in their body cells. The big question is whether Homo erectus had 46 or 48. If the latter, then the descendants of any hybrids between 48-chromosomed Homo erectus and 46-chromosomed humans would have had problems of chromosome incompatibility and would probably not have been viable. Some Christians, on the other hand, think that the great bottleneck occurred about 2 million years ago, when Homo erectus appeared. Time will tell.
J-Mac:
Hang on. Adam and Eve, after the Fall, were mortal. If they were capable of dying, then they obviously accumulated mutations over the course of their lifetimes.
The ages in the Genesis genealogies are likely symbolic: Lamech, for example, has a son at the age of 182 (half the number of days in a year), and dies at the age of 777.
We still don’t know what the mutational rate was like, hundreds of thousand of years ago. Personally, I suspect it wasn’t that different from what it is today.
keiths,
On Adam and Eve, you ask:
In six words: pride and a desire for autonomy.
There are several meanings of perfect which are being confused here:
(i) free from faults or defects;
(ii) perfect in character, when they were created, but capable of doing wrong at some later time; and
(ii) perfect in character, for all time.
According to traditional Christian theology, Adam and Eve were perfect in senses (i) and (ii), when they first appeared, but not (iii). After the Fall, they were perfect in neither sense.
The Fall would only be impossible if Adam and Eve were created perfect in sense (iii).
J-Mac:
keiths:
Vincent:
Then they weren’t perfect. Excess pride and a desire for autonomy caused them to sin.
God’s creation wasn’t perfect after all. He is ultimately responsible for the Fall.
ETA: I see you edited your comment while I was composing my response. Let me take a look at what you added.
keiths:
Excessive pride couldn’t have caused Adam and Eve to sin in the first place, as excessive pride is a sin, as is the desire to be independent of God.
Vincent,
I’ve read the edited comment, but your argument still doesn’t work.
You write:
To be perfect in sense (i) precludes sense (ii). If a being does wrong at some later time, it isn’t perfect at that time. Where does the imperfection come from? It can’t come from them, because they were perfect one moment prior.
And if it came from Satan or some other external influence, then God is still ultimately responsible. He created everything, after all.
Vincent,
The same counterargument applies. Whatever the very first sin was, it had to come from a person who was perfect the moment prior. Perfect people don’t sin. Where did the imperfection come from?
John Harshman,
To be honest, I’m a little leery of Dr. Gauger’s proposed reconciliation of the Adam and Eve account with the data from genetics, as it has been critiqued by Paul McBride here. McBride points out that five major haplotypes of HLA-DR all pre-date the genus Homo and concludes that an original couple is an impossibility. He may be correct here, but one could still argue that the minimum required number of ancestors would still be very small. Even if there wasn’t an original first couple, there may have been a small original first tribe, headed by Adam. I don’t know.
McBride also mentions Li and Durban’s 2011 paper, but I think Dr. Buggs has addressed that paper satisfactorily.
keiths:
“Perfect people don’t sin.” That’s like saying that fit people never get fat. The fallacy in the argument is the same in both cases.
Vincent,
That makes no sense. You’ve been arguing for sin as a privation. Where does the privation come from, if there was no privation the moment before?
Then why do you mention it? Can we agree that the number of cross-species polymorphisms in HLA renders the 2-person bottleneck so unlikely that we can reject it? And if you must then flee to a 3-person bottleneck (Lilith?), how is that theologically different from no bottleneck at all? Why even bother?
Now, what about that doctrine of original sin? Can you defend it?
The first part of my reply to Richard will (I think) go up at BioLogos tomorrow. I’ve already emailed a draft to Richard, so he has seen it (prior to some edits). It covers the issues that heterozygosity is not the same thing as genetic diversity, and that human allelic diversity is consistent with an old, large population rather than a bottleneck to two. I also preface my remarks with discussing how science does not offer “proof” – but rather converging lines of evidence for hypotheses we have not yet rejected. This is also how I frame it in Adam and the Genome:
“As our methodology becomes more sophisticated and more data are examined, we will likely further refine our estimates in the future. That said, we can be confident that finding evidence that we were created independently of other animals or that we descend from only two people just isn’t going to happen. Some ideas in science are so well supported that it is highly unlikely new evidence will substantially modify them, and these are among them: The sun is at the center of our solar system, humans evolved, and we evolved as a population.” (p55).
… and in the second part of the reply, I’ll deal with LD analyses (and possibly get to PSMC). As I mentioned in an email to Richard, it’s a long way down from thousands to just two…
Welcome to TSZ, Dr Venema.
Sorry your initial comments were held in moderation. Any future comment will appear immediately.
Dennis Venema,
How would you support this claim and avoid the logical fallacy of false analogy? There are a lot of molecular issues that need to be resolved in human evolution.
Orphan genes, gene expression differences and alternative splicing differences to name a few.
That’s a “God-of-the-gaps” argument, Bill. What do you do when further supporting evidence for common descent emerges?
Alan Fox,
This is an argument that human evolution is not as well established as the sun being the center of our solar system as supported by observation and general relativity. Dennis has way over sold the theory as demonstrated by his logical fallacy.
There is no model or experimental evidence to support his claim.
How you labeled this as a ” God of the gaps” argument is beyond me.
Because you appear to be saying that the evidence for common descent is incomplete:
Before anyone can address those issues, you have to explain more clearly and completely what they are. Why are those problems for human evolution?
Alan Fox,
Less complete then the theories he is trying to compare it to. My claim is false analogy.
The supporting evidence for these claims is very strong, and I discuss it at length in the book. If you’d like to see my take on it, that’s where I would start. I’ve also written extensively on this over at BioLogos.org.
Find a fossil that is transitional between tow others and you now have two gaps instead of one. Evolution falsified. See. That was easy.
There is no “experimental evidence” to support that the center of the solar system is the Sun, either. It is all inference from observations of data, just like with evolutionary relationships between species.
Nobody has build experimental solar systems in any other ways than by computer simulation, but you are generally in the business of blindly rejecting computer simulations if they result in things you disagree with. Why the double standard?
Rumraket,
This is supported by general relativity which has an experimentally validated mathematical model.
If the sharing of a common ancestor between chimps and man is so straight forward why can’t we model it?
You just model the daily weather back then, since it’s important to the evolution of humans, and we’ll model everything else.
What, you can’t model the weather back then?
Glen Davidson
Evolutionism must PROVE its one of them while proving its true. Your making another proof necessary for evolutionism.
Anyways.
You put on creationists to FIND EVIDENCE we were created independently or from a single pair.
Wait a minute.
Its up to you to demonstrate evidence we were not created independently and impossible from a single pair.
Your group exists because your failing to do this especially amongst bible believing Christians.
Words and word phrasing matter!!
by the way genetic issues always are based on evolutionist gentics conclusions about how genes change.
The bible is clear that genes change upon instant need. such as in migrations of peoples from Babel into areas where thier bodyplans changed ionstantly. Black and white are sudden reactions within a generation and so the genes went along for the ride.
In fact the bible explicitly presumes black people changed into black from a original post flood population of everyone in one group. The black colour is more dramatic reaction. I can’t remember the verse but its there.
You can’t persuade bible believes that evolutiion is true since first it rejects Gods word, which we already accept, and then your side provided NO biological scientific evidence worthy of modern thinking man.
Its not 19th century upper class bBritain trickle down wisdom ANYMORE.
Hey why don’t you give us your top thre bio sci evidences for evo.
I say you have none. Not just not good but NONE!
stcordova,
You missed the point. Again.
I was pointing out that there is still a difference between the two bottlenecks, 2 and 10,000, depending on how the post-bottleneck population size changes, using the steady state as a baseline for illustrative purposes. Not only do you need to game the heterozygosity (for some reason …) you need to game the subsequent population history (for some reason…). Maybe you need to add multiple mutations at the same time, rather than allowing them to progress by non-mutational frequency change, to help make it look like 10,000. Because you’re God, but (for some reason …) you can only fiddle.
I’d still like to see an actual ‘forward’ model from 2 to support the idea that backward-looking analysis of 10,000 is wrong.
vjtorley,
I don’t think we need worry about the actual species involved, but there is not a universal barrier against hybridisation between individuals of diifferent chromosomal count. If there were, I think we’d hear a tad more about this from Creationist sources! Chromosome number would never change, and clearly it does, in related taxa or even in single populations. Some populations are polymorphic for breaks/fusions. Although these can reduce interfertility, they don’t always do so by such an an extreme amount as to prohibit fertile matings – after all, being commonly descended, the genes can still line up!
A break or fusion may have to drift against the ‘selective wind’ of mild detriment to pass 50% frequency. But having done so, that selective wind is now in its favour.
Hi keiths,
You seem to be appealing to a very strong form of the Principle of Sufficient Reason: you’re insisting that there has to be an explanation for non-being, as well as being. You’re also insisting that any explanation of X has to be a sufficient condition for X. Needless to say, I don’t accept your version of PSR.
The version of PSR which I (and Scholastic philosophers) defend is much more modest: for every being which exists, there has to be something which is adequate to explain it. Note that “adequate explanation of X” does not mean “necessary and sufficient condition for X.” It simply means that nothing else is required for X to happen.
You could use this modest version of PSR to explain privations as well, if you wanted to. In that case, the adequate explanation for a lack of X is simply something which is able to fail to bring about X.
So in the case of a defective moral agent (i.e. a sinner), if you ask, “Where does the privation come from, if there was no privation the moment before?”, I would simply answer: from the agent. Nothing more needs to be said, unless you’re a Leibnizian, which I’m not.
Hi Alan Miller,
You make a telling point. Inter-breeding must still be possible, following a change in chromosome number.
I certainly wasn’t intending to promote creationism as such. The article I linked to in my comment above was written by Dr. Manuel Ruiz Rejón, Doctor of Biological Sciences and Professor of Genetics for 40 years at the Universities of Granada and Autónoma de Madrid. I’ll quote the relevant passage (bolding is the author’s, not mine):
Obviously, Dr. Rejón assumes that humans and apes share a common ancestor, but he still seems to think that once 46-chromosomed hominins emerged, they would have had a hard time interbreeding with their 48-chromosomed contemporaries. Is he wrong here? He also thinks that “there is a possibility that the chromosome fusion that originated our chromosome 2 may have been associated with the appearance of our distinctive characteristics.” What do you think?
Hi everyone,
The first part of Professor Dennis Venema’s reply to Dr. Richard Buggs has been posted online at Biologos:
Adam, Eve and Population Genetics: A Reply to Dr. Richard Buggs (Part 1) (November 3, 2017).
I have to say that Professor Venema makes what appears to be a very strong case.
The vast majority of Christians do NOT believe in a literal interpretation of ADAM & EVE!!!!!
Those who do hold such beliefs are a fringe minority akin to mindless drones beholden to the Moonies and the Hari Krishna fer cryin out loud!
Neither do Jews – and given the Jewish unchallenged command of Biblical Hebrew, deference should be made to their interpretation!
It boils down to the very first word in Genesis: “B’reshid”
“In the beginning of God’s creation of Heb. בְּרֵאשִית בָּרָא. This verse calls for a midrashic interpretation because according some Creationists’ simplistic and literal interpretation, the vowelization of the word בָּרָא, should be different.
Jewish scholars from time immemorial have realized that the sequence of the Creation as written is IMPOSSIBLE… and Genesis is NOT to be read literally!
Meanwhile, many commentators (especially of kabbalistic bent) have long interpreted Genesis to be totally compatible with Evolution.
Please – no more straw-man arguments and can we please get real here and move on?!
Hi John Harshman,
The way I see it, in order to preserve the doctrine of Original Sin, you need, at the very least, a single decision made at the dawn of human history, in which the human race rejected God. Christians refer to this event as the Fall. Obviously, if humanity is descended from a single primal couple, the Fall is very easy to envisage. But if the human line passed through a somewhat larger bottleneck, it would still be possible to believe in the Fall, if there was a collective decision made by the human race as a whole, headed by some individual whom we’ll call Adam. For instance, he might have been the leader of a tribe, and the tribe might have agreed to abide by his decision, whatever it turned out to be. (A foolish trust, you might say, but people often are foolish.)
So how big were tribes back then? It’s hard to say exactly, but this is what I dug up from an article written for the Khan Academy, which lists a supporting bibliography:
It wouldn’t be too hard to imagine Adam as the leader of a band of 20 people. Adam as leader of a tribe of 500 would be a stretch: he’d have to have superb political skills to persuade that many people to abide by his decision. You’d also have to imagine all these bands coming together for some reason, even if only for a short time.
I’m not the only Catholic who thinks that Adam may have been the leader of a community. Catholic apologist Jimmy Akin, who’s head of Catholic Answers, wrote back in 2005:
So how would Original Sin work? Remember that the Catholic Church defines it negatively, as a deprivation of original grace: since the Fall, none of us are born children of God. But how is it transmitted to us all? The Catechism is enigmatic, offering only the briefest outline of an explanation:
What the Church is saying here is that we are not completely separate individuals: the destiny of one individual may be intertwined with that of other individuals, on a spiritual level. Somehow, the decision made by Adam, as the spiritual father of the human race, had ripple effects on all human beings who have been born since the Fall. Don’t ask me how. It may seem an odd doctrine to many, but I personally have no trouble believing it – assuming, of course, that there could have been a unique event that Christians refer to as the Fall. I’m still waiting to see how the dust settles in the controversy between Dr. Buggs and Professor Venema, before I make up my mind.
vjtorley,
I think he’s going beyond what the data permits. We have to allow the possibility that some latitude is possible in chromosome number, and if the only thing we know is the numerical difference, we can’t assess the selection coefficients [eta – it’s of the same status as my ‘guess’ on Adam and Eve’s interfertility given high heterozygosity!].
Even if all heterozygotes for break/fusion suffered a fitness penalty, drift can promote the new ‘allele’ (break or fusion) to some frequency in the population. As it becomes more common, it suffers fewer heterozygous matings, and so its detriment is frequency dependent. The commoner it gets, the better it does. It is substantially easier for such a change to go to fixation than one of equivalent selection coefficient lacking this component of frequency dependence. Add to this a steady ‘rain’ of such translocations, and it becomes inevitable that some will fix.
I’m very doubtful about this. I don’t think the fusion plays a mechanistic role in ‘what makes people people’. There is certainly a theoretical possibility that this can cause speciation if the penalty for heterozygotes is severe enough, though that’s a somewhat different point. I don’t think it a common mechanism though. I just think it something that happened ‘along the way’ in our lineage.
One reader insists that Adam and Eve are a fringe belief, even among Jews and Christians. Really? Before I comment any further, let me just say that I tend to be somewhat mistrustful of people who use block capitals in their posts.
By the way, according to a 2014 survey of Americans conducted in 2014, 56 percent believed that Adam and Eve were real people, and 44 percent claimed to be certain of that fact. When we factor in the growing number of Americans with no religious affiliation, I think we can safely conclude that most American Christians still believe in Adam and Eve. And certainly the same would hold true for African Christians. Latin Americans are divided: about 40% are still creationists, and I suspect that quite a few theistic evolutionists still believe in an historical Adam and Eve, too. And it seems that about half of all Russians are creationists. Most European Christians probably reject Adam and Eve, but there aren’t many Christians left in Europe anyway. So to portray belief in Adam and Eve as a fringe belief as wildly inaccurate, whatever you think of the idea.
What about Jews? Contrary to popular perception, it appears that Orthodox Judaism commands the allegiance of between 33 to 45 percent of all the Jews in the world and 50 to 70 percent of those who identify as religious in some way. Most Orthodox take the idea of Adam and Eve very seriously (see also here).