The 'Out of Africa Eve Hypothesis'

[Carrikature]

It is not simply the most common ancestor. Why her and not anyone of the other tens of thousands of women?

I think this has been amply covered.

Wow!! what a comparison, A meteor as big as New York and the mutation in Mitochondria.

What mutation? That's your claim, not mine. A meteor is an extreme example of chance affecting which lineages ultimately succeed.

[shunyadragon]

I think this has been amply covered.

I do not believe so.

mutation? That's your claim, not mine.

This reflects it has not adequately covered.

simple basic genetics, genetic differences are due to mutations. The estimate of the age of the Mitochondrial Eve is based on the estimate of the mutation rates over time.

Source: http://en.wikipedia.org/wiki/Human_mitochondrial_molecular_clock

The human mitochondrial molecular clock is the rate at which mutations have been accumulating in the mitochondrial genome of hominids during the course of human evolution. The archeological record of human activity from early periods in human prehistory is relatively limited and its interpretation has been controversial. Because of the uncertainties from the archeological record, scientists have turned to molecular dating techniques in order to refine the timeline of human evolution. A major goal of scientists in the field is to develop an accurate hominid mitochondrial molecular clock which could then be used to confidently date events that occurred during the course of human evolution.

Estimates of the mutation rate of human mitochondrial DNA (mtDNA) vary greatly depending on the available data and the method used for estimation. The two main methods of estimation, phylogeny based methods and pedigree based methods, have produced mutation rates that differ by almost an order of magnitude. Current research has been focused on resolving the high variability obtained from different rate estimates.

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A meteor is an extreme example of chance affecting which lineages ultimately succeed.

Bizzaro!!!

[shunyadragon]

I messed up the quote tags.


ETA:
Even so, he did quote himself and agreed with himself.

of course.

[shunyadragon]

It's an intrinsic property of any stochastically reproducing entity with a finite population size, even in the absence of selection. The contribution of any particular lineage to subsequent generations is a one-dimensional random walk with two terminating states: extinction and fixation (technically, it's a martingale Markov process with two absorbing states); as time goes to infinity, the probability that each lineage will end up in one or the other state approaches one. The behavior of this kind of system is very well understood mathematically, whether you happen to be aware of it or not.

'. . . even in the absence of selection.' should not be an option in a realistic model. A realistic model should assume that natural selection is taking place over time. This is the reality of the fossil and genetic evidence of human evolution.

I believe that there are three possibilities which the above is too simplistic too consider the alternative, simply without selective genetic advantage the Mitochondrial Eve remains one of many in the diversity all the other women with different mitochondria.

The expected time for one lineage to completely take over the population varies depending on the specifics of the organism and how you're modeling it. In a Wright-Fisher model, which is a pretty good model for humans, the answer(*) was worked out by Kimura using diffusion theory and by Kingman using coalescent theory. You can find the results in any introductory textbook on population genetics (e.g. Hartl and Clark), and it's all over the web, e.g. on p. 19 here.

I will object here to the . . . 'varies depending on the specifics of the organism and how you are modeling it,' is too loosey goosey to get a model to agree with the results you want.

(*) I posted the wrong answer previously, by the way: the expected time is N_e, not N_e/2; the latter is the expected time for the most recent common ancestor for two lineages, not for all lineages.

Each possible lineages should be considered in the model.

[Roy]

[QUOTE=shunyadragon;158838]

It is not simply the most common ancestor. Why her and not anyone of the other tens of thousands of women?

Chance. Female lineages die out whenever a female either dies childless or raises only sons. While the former might be affected by selection on the genes in that lineage - although there's no reason to think that the common ancestor had any genes that weren't present in other females of her time - the latter isn't.

Roy

[shunyadragon]

Chance. Female lineages die out whenever a female either dies childless or raises only sons. While the former might be affected by selection on the genes in that lineage - although there's no reason to think that the common ancestor had any genes that weren't present in other females of her time - the latter isn't.

Roy

Poor excuse, chance does not explain this nor other patterns of mutation in evolution. Chaos models does give some explanation what was called chance or randomness in the past.

That does not explain that only one of tens of thousands of women remains the only Mitochondrial Eve had descendants today.

[sfs1]

'. . . even in the absence of selection.' should not be an option in a realistic model.

You are again wrong. Most mutations in humans are effectively neutral. If you ignore neutral evolution in any model of human genetics, your model will be nonsense.

Your argument is also a little lacking: you know that selection had to be involved in mitochondrial Eve being the last common ancestor, because you refuse to consider any model that doesn't have selection. Really?

Look, I explained why evolution will produce a single common ancestor even without selection acting. If you didn't understand my explanation, ask questions. There's really no point to you posting vague criticisms of a field you don't understand.

[shunyadragon]

You are again wrong. Most mutations in humans are effectively neutral. If you ignore neutral evolution in any model of human genetics, your model will be nonsense.

I am perfectly aware of neutral mutations, but that is not where the action is at. You are apparently ignoring the fact that the neutral mutations are meaningless in this discussion. The mitochondrial Eve is the result of a mutation in the Mitochondria, and the process of evolution is the result of mutations that have an impact on changes that result in species.

Your argument is also a little lacking: you know that selection had to be involved in mitochondrial Eve being the last common ancestor, because you refuse to consider any model that doesn't have selection. Really?

Really!!!!! Because natural selection is the source of the Mitochondrial Eve, and name of the game in the history of the evolution of humanity. Neutral mutations are essentially meaningless and not meaningful when we are addressing change over time. As far as I am concerned the only ones that emphasis 'neutral mutations' as important are those that oppose evolution in some way.

The mutation that 'marks' the Mitochondrial Eve may itself be a neutral mutation, but the reason she is the mother of humanity is likely due to mutations of selective benefit that made her the dominant line to modern humans. It is also possible the small population she belonged to had a natural selective advantage due to mutation(s)over other populations over time.

Look, I explained why evolution will produce a single common ancestor even without selection acting. If you didn't understand my explanation, ask questions. There's really no point to you posting vague criticisms of a field you don't understand.

Not vague criticisms at all the option of 'without selection' is literally meaningless when it comes to a dialogue concerning evolution and change over time which is the real natural case by the evidence, because 'neutral mutations are meaningless' to the discussion and natural selection and change in genetics over time is the basis for the theory of the Mitochondrial Eve and evolution in any context.

[Roy]

Poor excuse, chance does not explain this nor other patterns of mutation in evolution.

But shunya, the idea of mitochondrial eve isn't about mutation. If you start with a population containing N females you would expect the population to only have a single female ancestor after 8*log(N) generations even if there was no genetic variation at all, simply because in each generation some females have more than one daughter and others have only sons. This is simply statistics, and it can be demonstrated easily. Try it.

That does not explain that only one of tens of thousands of women remains the only Mitochondrial Eve had descendants today.

No, most of them will still have descendants today. But not many will have descendants via only female offspring.

The mitochondrial Eve is the result of a mutation in the Mitochondria, ...

This is a misconception. There is no need for mitochiondrial Eve to have had any mutations in her mitochondria, only that her lineage produced lots of daughters. She may have had particularly successful genes, but not necessarily, and even if she did she didn't need to be the first person who possessed them.

Roy

[shunyadragon]

But shunya, the idea of mitochondrial eve isn't about mutation. If you start with a population containing N females you would expect the population to only have a single female ancestor after 8*log(N) generations even if there was no genetic variation at all, simply because in each generation some females have more than one daughter and others have only sons. This is simply statistics, and it can be demonstrated easily. Try it.
No, most of them will still have descendants today. But not many will have descendants via only female offspring. This is a misconception. There is no need for mitochiondrial Eve to have had any mutations in her mitochondria, only that her lineage produced lots of daughters. She may have had particularly successful genes, but not necessarily, and even if she did she didn't need to be the first person who possessed them.

Roy

simple basic genetics, genetic differences are due to mutations. The estimate of the age of the Mitochondrial Eve is based on the estimate of the mutation rates over time.

Source: http://en.wikipedia.org/wiki/Human_mitochondrial_molecular_clock

The human mitochondrial molecular clock is the rate at which mutations have been accumulating in the mitochondrial genome of hominids during the course of human evolution. The archeological record of human activity from early periods in human prehistory is relatively limited and its interpretation has been controversial. Because of the uncertainties from the archeological record, scientists have turned to molecular dating techniques in order to refine the timeline of human evolution. A major goal of scientists in the field is to develop an accurate hominid mitochondrial molecular clock which could then be used to confidently date events that occurred during the course of human evolution.

Estimates of the mutation rate of human mitochondrial DNA (mtDNA) vary greatly depending on the available data and the method used for estimation. The two main methods of estimation, phylogeny based methods and pedigree based methods, have produced mutation rates that differ by almost an order of magnitude. Current research has been focused on resolving the high variability obtained from different rate estimates.

© Copyright Original Source

[sfs1]

I am perfectly aware of neutral mutations, but that is not where the action is at. You are apparently ignoring the fact that the neutral mutations are meaningless in this discussion. The mitochondrial Eve is the result of a mutation in the Mitochondria, and the process of evolution is the result of mutations that have an impact on changes that result in species.

I'm not ignoring that fact because it's not a fact. It's an error that you dreamed up. Your entire support for your claim is that you keep repeating it.

Really!!!!! Because natural selection is the source of the Mitochondrial Eve, and name of the game in the history of the evolution of humanity. Neutral mutations are essentially meaningless and not meaningful when we are addressing change over time. As far as I am concerned the only ones that emphasis 'neutral mutations' as important are those that oppose evolution in some way.

Yes, really. The Neutral Theory of Evolution was not dreamed up by someone who opposed evolution. Do you ever learn about the subjects you write about, or do you always just go with your gut feelings?

The mutation that 'marks' the Mitochondrial Eve may itself be a neutral mutation, but the reason she is the mother of humanity is likely due to mutations of selective benefit that made her the dominant line to modern humans.

And you know this because . . . ? Here's where you supply evidence for your claim, rather than simply repeating it again.

Not vague criticisms at all the option of 'without selection' is literally meaningless when it comes to a dialogue concerning evolution and change over time which is the real natural case by the evidence, because 'neutral mutations are meaningless' to the discussion and natural selection and change in genetics over time is the basis for the theory of the Mitochondrial Eve and evolution in any context.

How would you know? How many papers have you published on mutation, evolution or population genetics? You do realize I do this for a living, right?

[shunyadragon]

I'm not ignoring that fact because it's not a fact. It's an error that you dreamed up. Your entire support for your claim is that you keep repeating it.

I gave a reference, you have offered no references. I will offer more.

Yes, really. The Neutral Theory of Evolution was not dreamed up by someone who opposed evolution. Do you ever learn about the subjects you write about, or do you always just go with your gut feelings?

No, references which you have failed to provide. The concept of the Mitochondrial Eve is based on mutation rate over time. You either need to retract your previous statement, or give an explanation and references of how mutation are not the basis of the Mitochondrial Eve theory.

And you know this because . . . ? Here's where you supply evidence for your claim, rather than simply repeating it again.

And you know because . . . ? Just air balls, no references.

I am perfectly aware of the concept of neutral evolutionary theory, and mutations over time remain central to the concept. The disagreement, not resolved, is whether natural selection or genetic drift dominate in evolution over time, but nonetheless genetic mutations play a role in both processes. It is likely that both play a role in evolution over time. Genetic drift likely does take place over time due to genetic mutations, but does not likely give a complete explanation for evolution. There is abundant evidence that change does take place with adaptation to selective pressure due to changes in the environment and competition regardless of whether natural selection or genetic drift dominates.

Again simply punching a calculator does not explain why modern humans all descended from one Mitochondrial Eve.

How would you know? How many papers have you published on mutation, evolution or population genetics? You do realize I do this for a living, right?

Wrong!?!?!!? You have cited nothing of substance to support your assertions in your publications, nor other publications. I believe you are misusing the concept of 'neutral evolution theory' when you make statements like; 'But shunya, the idea of mitochondrial eve isn't about mutation.' (Wowsers!! What a statement.) I gave a reference that is concise and has references to other sources. You have ignored them and provided nothing in response. All you could do is present one view, Neutral Evolutionary Theory, where genetic drift dominates, this does not resolve anything, because genetic mutation still takes place over time, and change resulting from evolution still takes place due to 'mutations.'

Source: http://en.wikipedia.org/wiki/Neutral_theory_of_molecular_evolution

A heated debate arose when Kimura's theory was published, largely revolving around the relative percentages of alleles that are "neutral" versus "non-neutral" in any given genome. Contrary to the perception of many onlookers, the debate was not about whether natural selection does occur. Kimura argued that molecular evolution is dominated by selectively neutral evolution but at the phenotypic level, changes in characters were probably dominated by natural selection rather than genetic drift.[11]

After flirting (in 1973) with the idea that slightly deleterious mutations may be common, Tomoko Ohta emphasized the importance of nearly neutral mutations.[12] However, the population dynamics of these mutations is essentially the same as that of neutral mutations unless selection coefficients are significantly greater or smaller than 0.[7][8] Note also that the neutral theory does not assume the strict neutrality of alleles but that the allele frequency changes are dominated by genetic drift.[1]

There are a large number of statistical methods for testing neutral evolution (e.g., McDonald-Kreitman test [13]), and many authors claimed detection of selection [Fay et al. 2002,[14] Begun et al. 2007,[15] Shapiro et al. 2007,[16] Hahn 2008,[17] Akey 2009.[18]] However, Nei et al. (2010).[19] have indicated that these methods depend on many assumptions which are not biologically justified.

© Copyright Original Source

Your brief mention in your profile is insufficient to justify your claims, and publications??, to support your argument.

[sfs1]

I gave a reference, you have offered no references. I will offer more.

I started a detailed response, but that would just lead to endlessly bifurcating paths through the woods of confusion. Let's stick to basics. You are claiming that Mitochondrial Eve -- the most recent common ancestor of all humans by matrilineal descent -- had to be the unique ancestor because there was something special about her, that she had some kind of selective advantage.

Provide some evidence to support that claim. Not evidence that mutations are important, or that natural selection exists, or that you can google "Neutral Theory". Evidence that the most recent common ancestor for any locus had to have a selective advantage. So far you've provided no evidence at all. (And yes, I did give you a reference: I gave you a link showing the expected time to the most recent common ancestor of mitochondria in the absence of selection -- the ancestor you claim couldn't exist.)

[Roy]

simple basic genetics, genetic differences are due to mutations. The estimate of the age of the Mitochondrial Eve is based on the estimate of the mutation rates over time.

True. But you weren't querying the age estimate, you were querying "...that only one of tens of thousands of women remains the only Mitochondrial Eve had descendants today." Mutation rates will provide an estimate of how long ago the mitochondrial Eve lived, but they aren't necessary to determine that there was one, and they won't tell you whether her genetic make-up was unique to her. In fact, the calculation you refer to is dependent on the assumption you are seeking an explanation for.

Incidentally, converting the time since the mitochondrial Eve into an approximate number of generations can provide an order of magnitude estimate of the population then, assuming no bottlenecks or strong mitochondrial selection since.

The concept of the Mitochondrial Eve is based on mutation rate over time.

No. The concept of mitochondrial Eve is based only on mitochondria being inherited along the female line of descent.

Roy

[Roy]

Again simply punching a calculator does not explain why modern humans all descended from one Mitochondrial Eve.

What's the alternative? Under what circumstances would there not be a mitochondrial Eve?

Roy