The time scale of the bottleneck?

Richard has accepted 95% as reasonable over in the thread you mentioned. But I have never been able to get an answer as to what exactly 95% similarity actually means.

Gen 5:4 The days of Adam after he became the father of Seth were eight hundred years; and he had other sons and daughters. Incest was not forbidden until ~2000 years later so they married sisters. The exact number of children isn’t stated in the Bible

Brothers, cousins? We aren’t told exactly when Cain killed Abel, only " In the course of time". The total number of Adam’s children is not given in this work; however, it is found as a footnote in The Works of Josephus where it states: “The number of Adam’s children, as says the old tradition, was 33 sons and 23 daughters.” Ref

From Never Thirsty “If we assume that Adam and Eve gave birth to other sons and daughters (one per year starting at 20 years of age), who had sons and daughters and so on, there could have been at least ten thousand people by the time Adam was 130 years old.” I think 1/year is probably a bit high but even so there could have been a significant population for Cain to deal with. However note that Adam and Eve didn’t have to wait 20 years to begin having children because they were created as mature adults.

And smart! Did you realise that on the first day of his life Adam could walk, talk, name all the animals, and he spoke every language in the world.

Where are you getting this from? I thought the evidence rather clearly supported a genetic bottleneck between 100,000 to 200,000-250,000 years ago in southern Africa, a few thousand survivors of an ice age which made most of the earth nearly uninhabitable. This is also supported by evidence showing human migrations from southern Africa to the rest of the world from 100,000 years ago. But perhaps you are talking about only two ancestor alone, in which case what you say makes a little more sense, not that this possibility is really all that believable. Not to mention the fact that hominids from that long ago (400,000 to 700,000 years ago) were not really the homo sapiens anyway.

From memory I don’t think he did. That might have been an upper limit, but he still gave a range with an average of less than 90%. It also depends on how much is removed as indels before the calculation is done, and how much is excluded for other reasons.

I see… so you want to rearrange the order of the story, and instead of Adam and Eve having a third son, Seth after Cain killed Abel, you want to move the story of Cain and Abel to later in the Bible after all these these other children. Well… yeah… I have no doubt that you can rewrite the Bible to make it fit if you really want to. But since I see no reason to alter the Bible in order to make it incompatible with the findings of science, these alterations look quite bizarre to me.

In his final post in the thread I don’t see any mention of a lower bound. Or are you remembering this?

The old gaps approach…

The fact is that the more we study the capabilities of the primates the more we find that they have all the same capabilities. So I see no reason not to go with the scientific findings which has so far increased from an initial estimate of 97% to a more recent estimate of 99%.

What gaps?

It all depends on how exactly you define “similarity”. After the rather long discussion on the Human Chimp Genome Similarity thread 95%, using the definition in that thread, appears to be a reasonable estimation.

I refer to “God of the gaps” type arguments. This is seen in the way you hide your belief in what science does not know and make the sucker’s bet that future development will not prove you wrong, even though current evaluations of the evidence does not agree with what you prefer to believe.

Indeed! For some people surface superficialities like shape, color and sex are the most important things for their identity and thus they make these things of theirs the measure of humanity. The surface differences from chimpanzees are obvious so it is hardly surprising that the DNA is different, something must account for that. But are these the important differences. Are the important differences the genetic ones at all, or is there something more important, something more essential to our humanity? I think so!

If pigs could talk and complain about their treatment would you still be arguing percentages of DNA? Is the fact that they don’t look like us really all that important? Is the fact that their DNA is different so important either? I reject a world which lives by such an attitude. After all, what percentage similarity is enough? At one time people in this country might have compared the DNA of black people and made that their justification for slavery, and at other times and place they would have done the same for women.

Thus I utterly reject the idea that our humanity is defined by a genome. We are human because of something entirely different. It is the human mind and abstract capable language from which it is built which really makes us what we are, and things like shape, color, and sex are irrelevant. Furthermore I would argue that if you compare the information carrying capabilities of DNA and human language, the latter is demonstrably superior.

Your agreements are irrelevant to me. The scientific measure is 99% or if you want greater precision 98.8%. But if you want to shift the question to importance of similarities and difference, well then you now know I think the important ones are not found in DNA at all.

Previously I think the number was 97% then they found that the portions which were different from the DNA in different species of chimpanzees were not the same, and that accounts for the additional 1.8%, for the point is that 98.8% of our DNA is found in one species of chimpanzee or the other.

You need to read the thread. The “agreement” was between several experts in the field with copious references to published papers. Do you have any papers that reference the 98.8% number?

BTW, no mention was made of defining humanity by the genome. The discussion was on common ancestry.

I agree with this. I believe something happened about 70,000 years ago, the great leap forward, that made homo sapiens into modern humans.

To be sure there are a lot of difficulties in making the comparison. For example, chimpanzees as well as some other apes and monkeys have 24 pairs of chromosomes while we only have 23 pairs. This is just one way in which we have to overlook less important differences to zero in on the differences which matter. The end result has been a determination by the scientific community is that when you boil this down to the differences which matter you get a 98.8 percent similarity.

But sure if you go hunting for excuses to inflate the differences then you can no doubt come up with bigger numbers for the differences. I am certainly not interested in the results of some internet discussion which has decided to split the difference between the inflated numbers and the determination by the scientific community.

The discussion is entitled “the time scale of the bottleneck” to which I gave 3 reasons why I would not agree with connecting Adam and Eve (and thus humanity) with the genetic bottleneck in our ancestry in Southern Africa 100,000 to 200,000 years ago. Thus arose the question as to what are the real differences between human beings and animals.

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This is a nice article highlighting how the types of difference we see among human genomes follow the same pattern of the types of differences we see between humans and chimpanzees - demonstrating that the same mechanisms are responsible for the difference:


What did Richard Buggs really say?
At post 35 he said;

In his last post he said;

So Richard Buggs has not accepted 95% as reasonable. It is still outside his upper bound estimate.

… , the human genome has between 84.4% and 93.4% one-to-one orthology …
Mean = 88.95%
Upper Quartile = 91.15%

I am able to accept that God is perfectly capable of using evolution to create life on Earth.
But I don’t think he did.

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George what am I missing? There were some migration bottlenecks of ~500 people or so within the pas 50,000 years but there is no evidence of any serious Homo sapien bottleneck, not even going back to common ancestors with chimpanzees. I’m not sure what we are discussing here. Are you talking about Y-chromosome Adam which here is a summary of some different methods:

@aarceng Brother Chris , I appreciate your congenial way of discussing things. It’s always good to have iron sharpening iron.


In the course of the conversation Richard did change his opinion on the % of similarity. So I noticed 2 things about his final comment way down at post 120. He no longer mentions a lower bound on his range estimate and admits that 95% is possible (otherwise it wouldn’t count as a prediction) but not yet an “established fact”. So perhaps instead of reasonable I should have said possible. Not much difference in my mind.

If I might ask, what do you think is the significance of a similarity of 93.4% or greater with the chimp?

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It seems to me that all the evidence including migration, Y-chromosomal Adam and mitochondrial Eve all agrees with a long bottleneck in the human population in southern Africa between 100,000 and 200,000 years ago, which could have gone as low as 2000 people. There is additional evidence of a migratory bottleneck from a migration across the Bering strait which could have been as few as 70 people. This, of course, rejects the Toba catastrophe hypothesis which the evidence hasn’t supported. This also seems to be the origin of modern homo-sapiens species which agrees with the logical link between low population and high genetic drift.

It seems to me the chart given for different estimates of the time for Y chromosomal Adams seems to agree rather well with this. The estimates place this as no more recent that 100,000 years ago and a few push this back to as far as 250,000 years ago. And it should be noted that older estimates do not logically disagree with the long bottleneck hypothesis 100,000 to 200,000 years ago.

What do you mean by ‘long bottleneck?’ I haven’t seen any papers with a bottleneck of 2,000 some people besides regional bottlenecks involving migration but not for the human genome as a whole. Could you point me to something you are looking at?

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This is an almost hopeless muddle. Neither Y-chr Adam nor mito Eve has anything to do with bottlenecks. I have personally never heard of a “long bottleneck” in southern Africa, though I do know of some old-ish theorizing about the species riding out a rough stretch by eating a lot of shellfish in Africa. Not my area, but I think that’s pretty speculative. No matter what, you should be wary of any discussion of bottlenecking that uses Y-Adam or mito-Eve as evidence. That’s a basic error.

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