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Author | Topic: Why is evolution so controversial? | |||||||||||||||||||||||||||||||||||||||
Dr Jack Member Posts: 3514 From: Immigrant in the land of Deutsch Joined: Member Rating: 9.2 |
It's presumable ultimately derived from the 1993 Takahata paper and it's a broadly quoted figure. Other more recent estimates have been a bit lower.
It's certainly the case that there have been significant bottlenecks in human population history and, accordingly, humans have a low effective population size.
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zaius137 Member (Idle past 3440 days) Posts: 407 Joined: |
Additionally they estimated the effective population size of the common ancestor of humans and chimpanzees to be ~100,000. This was somewhat surprising since the present day effective population size of humans is estimated to be only ~10,000. Human evolutionary genetics - Wikipedia
I used the wiki here, estimates do vary somewhat. I will have to go deeper for further conformation... Let us just accept a reasonable number to further our discussion.
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Taq Member Posts: 10085 Joined: Member Rating: 5.6 |
The "effective population (Ne)" is approximately 10,000 in the current population of ~ 7 billion. This could not be if there was not a recent origin or a recent bottleneck in human ancestry. Large populations of organisms drift by polymorphisms over large timespans, increasing the "effective population" unless they have experienced the above mentioned. You answered your own question. The reason for the low effective population is genetic bottlenecks.
Since the acceptance of indels as percentage divergence between humans and chimps, evolution can not maintain a 5.6 million year split between humans and chimps. Paleoanthropology can not accommodate the new similarity percentage of 95%. Since the acceptance of indels? We have known about indels since we were able to sequence DNA which has been decades. Also, why do 5 million indels in addition to 35 million substitutions pose a problem for the 5 million year estimated time since divergence?
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New Cat's Eye Inactive Member |
Got it, thanks.
But, that is neither evidence for a young genome nor that our DNA denies common descent. It is evidence of a bottle neck in the human population. We're aware of that.
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zaius137 Member (Idle past 3440 days) Posts: 407 Joined: |
quote: So when and how did your bottleneck happen?
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zaius137 Member (Idle past 3440 days) Posts: 407 Joined: |
quote: Simple Instead of being 1.33% divergent from chimps, we are now found to be 5% divergent from chimps. There are simply not enough beneficial mutations to explain a divergence from the chimp. As a side note, most mutations are either neutral or deleterious. Both are added to that genetic loading number in humans under soft selection and eventually have to be purged from a population to maintain a acceptable fitness in that population. Explain how you can account for the high U that would be imparted if mutation rates were met for a human chimp divergence of 5.6 million years? I can quantify that number but you would not like the result.
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New Cat's Eye Inactive Member |
So when and how did your bottleneck happen? If you would have kept reading after where you cut off your quote, you would have seen the following in the wiki page you linked to:
quote: That wiki link goes to:
quote: and:
quote: That's one theory. There's another that says:
quote: You can read the paper on that one here: Population Bottlenecks and Pleistocene Human Evolution | Molecular Biology and Evolution | Oxford Academic What makes you think that the human effictive population size means that the genome is young and that we can't have common decent?
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Genomicus Member (Idle past 1972 days) Posts: 852 Joined: |
The "effective population (Ne)" is approximately 10,000 in the current population of ~ 7 billion. This could not be if there was not a recent origin or a recent bottleneck in human ancestry. The molecular data suggests a recent bottleneck, not a recent origin. See Heng and Durbin (2011). In this study, the researchers used bioinformatic approaches to date the time of the bottleneck. If there were a recent origin, we wouldn't see things like: "Both populations experienced a severe bottleneck between 10—60kya while African populations experienced a milder bottleneck from which they recovered earlier." There's plenty of evidence in the literature -- utilizing different methods -- that suggest a bottleneck, rather than a recent origin. So this argument for a recent origin doesn't really stand up well in the light of scrutiny.
Since the acceptance of indels as percentage divergence between humans and chimps, evolution can not maintain a 5.6 million year split between humans and chimps. Paleoanthropology can not accommodate the new similarity percentage of 95%. Uh, you haven't explained why the theory of common descent is not compatible with the amount of indels that separate our genomes from the genomes of chimps. You're just saying it can't. Back that up with rigorous science. Reference Inference of Human Population History From Whole Genome Sequence of A Single Individual, 2011.
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Genomicus Member (Idle past 1972 days) Posts: 852 Joined: |
So when and how did your bottleneck happen? The paper I cited above gives a neat "when" to your question. How did the bottleneck happen? There are plenty of mechanisms for bottlenecks. Bottlenecks aren't implausible at all; we know they happen.
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Genomicus Member (Idle past 1972 days) Posts: 852 Joined: |
Simple Instead of being 1.33% divergent from chimps, we are now found to be 5% divergent from chimps. There are simply not enough beneficial mutations to explain a divergence from the chimp. This doesn't make much sense. Because our genome differs roughly 5% from the chimp genome, that means there couldn't have been enough beneficial mutations? Do you have something to back that line of thought up?
As a side note, most mutations are either neutral or deleterious. Both are added to that genetic loading number in humans under soft selection and eventually have to be purged from a population to maintain a acceptable fitness in that population. And:
Explain how you can account for the high U that would be imparted if mutation rates were met for a human chimp divergence of 5.6 million years? I can quantify that number but you would not like the result. Selection pressures can lead to a higher-than-average U value. That's nothing new. Edited by Genomicus, : No reason given.
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Dr Adequate Member (Idle past 315 days) Posts: 16113 Joined:
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Simple Instead of being 1.33% divergent from chimps, we are now found to be 5% divergent from chimps. There are simply not enough beneficial mutations to explain a divergence from the chimp. Ah, one of my favorite varieties of creationist nonsense ... the non-quantitative quantitative argument. Hooray, you can prove that you're right with numbers. But without any actual math, 'cos that's hard.
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New Cat's Eye Inactive Member
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Instead of being 1.33% divergent from chimps, we are now found to be 5% divergent from chimps. There are simply not enough beneficial mutations to explain a divergence from the chimp. We didn't evolve from the chimp. We evolved from a common ancestor with the chimp. How much of that divergence from chimps is due to our evolution from the common ancestor, and how much of that divergence is due to the chimps evolution from the common ancestor? Neither of us species hold all of the evolution from the common ancestor. Some of it is ours and some of it is their's.
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Taq Member Posts: 10085 Joined: Member Rating: 5.6 |
Simple Instead of being 1.33% divergent from chimps, we are now found to be 5% divergent from chimps. What do you mean "instead of"? Both of those figures are from the same paper, and they are measurements of different things. The 1.33% is a measurement of the number of changes in the DNA we still share with chimps. The 5% includes the divergence caused by DNA we no longer share, the DNA that has either been removed or added to each lineage. These are answers to different questions, not an "instead of".
There are simply not enough beneficial mutations to explain a divergence from the chimp. Based on what evidence? The 1.33% involves 35 milllion mutation events. The 5% involves the addition of just 5 million more mutation events. Why do you think the addition of just 5 million more mutations pushes it over the edge?
As a side note, most mutations are either neutral or deleterious. Yes, just as most atmospheric molecules are either nitrogen or radon.
Both are added to that genetic loading number in humans under soft selection and eventually have to be purged from a population to maintain a acceptable fitness in that population. Neutral mutations are not added to those genetic loading numbers.
Explain how you can account for the high U that would be imparted if mutation rates were met for a human chimp divergence of 5.6 million years? You would have to show that the U would be too high, first.
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zaius137 Member (Idle past 3440 days) Posts: 407 Joined: |
quote: All these bottleneck scenarios involve some kind of low population over extended time frames. That is not really tenable when you take into account the needed mutation rates for divergence between the human and chimp genome. A heavy mutation load in a small population tends to cause that population to be susceptible to sudden collapse (or a sustained downward spiral in population).
quote: The following is the calculation for a "U" given a needed mutation rate for a divergence of 5% (95% similarity) and a 5.6 million year divergence from human to chimp. 5.6 million years is 244 thousand generations (given 23 years per generation). t= number of generations since divergence (244 thousand)k= percentage of sequence divergence Estimated at 5% Ne= effective size of population ~10^3 (u)= mutation rate needed. u= k/(2t+4Ne) or 9.5x10^-8 or ~ 600 mutations per generation (mutation rate times the diploid genome in humans). Now calculating deleterious mutation rate (U) from the following suggesting that 1.7% of the genome is subject to constraint (normal estimate, citation on demand). This gives: (600x.017)= U = 10.7 (completely untenable) A acceptable amount by evolutionists would be around U=1.3. Calculating the statistical birth rate to avoid passing on deleterious mutations to the next generation by the poisson distribution. B = 2e^U (U=10.7)=88 thousand offspring needed per mating pair per generation. This is clearly impossible. I am sure most of you professionals can follow that calculation... If I need to, I will go over it step by step for you (maybe tomorrow). You can make up all the stories you like about how and when bottlenecks happen in a population but you must temper that story to real world conditions. Edited by zaius137, : No reason given.
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zaius137 Member (Idle past 3440 days) Posts: 407 Joined: |
quote: Please read what I said carefully.. I said diverged.
quote: All things made equal, most scientists will assume half in their calculations Citation on demand.
quote: True, but also true is that we are more closely related to the common ancestor than to the chimp. So did the common ancestor look more like us or like the chimp? I would say neither.
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