The time scale of the bottleneck?


(George Brooks) #1

Continuing the discussion from When was Adam's life on Earth?:

Continuing the discussion from (Michael Behe's view on common descent):

The time scale can be adjusted here or there… but it is certainly before the rise of Homo sapiens…


(Mitchell W McKain) #2

I cannot agree with a connection of Adam and Eve with the genetic bottleneck in Southern Africa 100,000 to 200,000 years ago for the following reasons.

  1. The reduction of humanity to biology and genetics, or even the overemphasis on genetics has numerous philosophical problems including connections with racism and eugenics.
  2. It is unreasonable to think that humanity is genetically derived from only two people alone and the Bible narrative doesn’t really support this anyway.
  3. The attempt to connect Adam and Eve to y-chromosomal Adam and mitochondrial Eve looks a bit too much like a gaps argument to me, which further discoveries are only too likely to disprove.

By genetics and biology alone the difference with the other primates is rather small. Our humanity must be found in the human mind and language for this is the one undeniable difference from the animals. Therefore, it is much more reasonable to associate Adam and Eve with a change in our thinking (a memetic difference rather than a genetic one) and thus with the beginning of human civilization which is closer to 10,000 years ago rather than 100,000 years ago.


(Chris) #3

I’m interested to hear how you conclude that “the Bible narrative doesn’t really support this anyway”. I would have thought that was exactly what Genesis teaches.

Genetically 2 people can have up to 4 alleles for each gene (less for the X &Y chromosomes) and with mutations accumulated since the fall the Adam & Eve hypothesis does not seem unreasonable to me.

Rather more than many people think. Sure we can get 99% similarity in some places but overall it is probably less than 90%. There’s another thread on this where Richard Buggs argues this. Since we’re both mammals a lot of genetic similarity could be expected. Also remember that since there are only 4 bases any two random stretches of DNA could be expected to have ~25% similarity so that’s your real “zero” point. But I agree that the essential differences between humans and apes is not our physical bodies but our cognitive and spiritual differences.


(Chris) #4

It would be contrary to the view of many scientists, however going back to the Wistar conference there are many who claim that purely natural mechanisms can’t produce the effects that are claimed for the theory of evolution.


(Mitchell W McKain) #5

Only using childish literalism which Jesus warned against and ignoring the things which do not fit.

  1. In Genesis 4:14, Cain is afraid people will kill him. What people? His parents? If he was afraid his parents would kill him then I think he would have said so. Instead, Cain speaks of a world so filled with people, there is nowhere he can go where he will be safe from people who would kill him. Doesn’t fit!
  2. Cain and Seth take wives and have children? Who did they marry? Even if you like incest, the Bible never speaks of Adam and Eve having daughters. Sure you can add your own passage to the Bible if you want but that is generally frowned upon. Again, it doesn’t fit.
  3. In Genesis 6:1-4 it speaks of the sons of God taking wives from the daughters of men. Everywhere else in the Bible, the sons of God and children of God refer to God’s chosen people, and thus the most obvious meaning of this passage is the answer to the problem in number 2. Cain and Seth married the daughters of all those other people out there who were not God’s chosen, and their children were men of reknown, and leaders of human civilization. And what do you have to do in order to avoid the obvious? You have to insist that sons of God means angels and that they bred with humans to create fairly tale giants. Talk about bending over backwards! Definitely, does not fit!

But hey, when you are going with the childishly literal interpretation with magical fruit, golems of dust and bone, and talking animals, all made by an ancient necromancer walking the earth long ago, then why not add a few other fantasies to your fairy tale. After all, they make for great books, movies, and comics – the crazier and more fantastical the better.


(George Brooks) #6

@aarceng

You need to read the giant thread… between Venema, Buggs and Gauger.

Even using maximum assumptions of genetic diversity between the founding male and female, the existing diversity of humanity doesn’t permit any bottleneck as recently anywhere between 400,000 years back to 700,000 years back.

If you want to use science, science will not support a YEC scenario and only half of an OEC scenario.


(George Brooks) #7

@aarceng

If you and I agree that God directed evolution, are you able to accept that God is perfectly capable of using evolution to create life on Earth.


#8

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.


(Chris) #9

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.


(Mitchell W McKain) #10

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.


(Chris) #11

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.


(Mitchell W McKain) #12

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.


#13

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


(Mitchell W McKain) #14

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%.


#15

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.


(Mitchell W McKain) #16

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.


#17

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.


(Mitchell W McKain) #18

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.


(Matthew Pevarnik) #19

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:


(Chris) #20

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.

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