I was just thinking that a relatively homogenous initial population would give the same result, but of course, that population had to come from somewhere...

This bad analogy give aid and comfort to the Ray Comforts of the world - and other creationist charlatans as well.

More importantly, it confuses well-meaning people.

This would be a great paper to use for discussion in my non-majors biology course, specifically to address the misconceptions that you highlighted in using this analogy. I usually try to avoid using analogies because so many of them either carry misinformation depending upon the background of the student reading/hearing it or they fail to penetrate because the analogy is to something unfamiliar to the student. Personally, I would avoid analogizing altogether on this one but I was wondering if you would be able to suggest a good analogy to replace the Adam/Eve one for this example?

Presumably, not even the entire Y chromosome came from a single individual, since there's still a little crossing-over (with X) occurring even there, as I recall.

Considering that could lead to the impartation of some knowledge of what a "Y Adam" can mean--as well as about the evolutionary origin of the Y chromosome.

Glen Davidson

Thanks for this. It is indeed difficult to get people to understand what the actual evidence says when using terms such as Adam and Eve. It is little wonder that people can get confused.

After getting the real scientific interpretation across, the next important message to communicate is the this is absolutely NOT evidence for the biblical Adam and Eve, indeed it is extremely strong evidence against that hypothesis, as if any more were needed.

I guess, for this, I would probably avoid analogy, and just talk about how cool it is that we can trace these lineages back in time (because they do not recombine). I'm working on a video to explain the concept of the mtDNA ancestor - hoping to finish it up tomorrow or Thursday - will post here.

I remembered reading here a long time ago something about how Y-Adam and mt-Eve are not really all that special. Every gene can be similarly followed back through its own separate lineage, and will eventually resolve to a (different) common ancestor. Y-Adam and mt-Eve are the ones talked about only because their lineages are passed down through a single sex, and are thus easier to work with than any of the others.

It took me a bit of searching (it was much further back than I'd thought), but I'm pretty sure that it was this PT entry that I remember. The url it links to doesn't work any more, but a quick search turned that up too, here.

It seems to me that, since the 2nd Genesis Story's bit on Adam and Eve is MYTH, the use of the as allegory doesn't matter. Yes, if they were real people, or if the original authors had intended them as real people, then they actually did have sex, and this would be all confusing. But they weren't. They're myth, to illustrate a deeper point. So I'm not getting why they would be a bad use for analogy for the public to pin something on to understand the further science. Perhaps someone could explain it further to me.

And Noah went in, and his sons, and his wife, and his sons' wives with him, into the ark, because of the waters of the flood [Genesis 7:7]

Jedidiah said: It seems to me that, since the 2nd Genesis Story's bit on Adam and Eve is MYTH, the use of the as allegory doesn't matter. Yes, if they were real people, or if the original authors had intended them as real people, then they actually did have sex, and this would be all confusing. But they weren't. They're myth, to illustrate a deeper point. So I'm not getting why they would be a bad use for analogy for the public to pin something on to understand the further science. Perhaps someone could explain it further to me.

Matt Young said: It seems to me that Y-chromosomal Adam is not Adam at all but Noah. Noah is the last common ancestor of all living males (according to the myth), not Adam. The Hebrew Bible says clearly,

And Noah went in, and his sons, and his wife, and his sons' wives with him, into the ark, because of the waters of the flood [Genesis 7:7]

and repeats the same information in verse 13. Now Noah was (presumably) the father of his sons, but he was (presumably) not the father of his daughters-in-law. Thus, Mitochondrial Eve is not Noah's wife, but Mitochondrial Adam is Noah, not Adam. Noah and Eve did not live at nearly the same time, incidentally, and they never met.

Why try to explain it in Biblical terms at all?

M. Wilson Sayres said: Nowhere in my post do I say that the analogy is bad because it is related to the Bible. It is a poor analogy because it leads to misunderstandings (namely that there were only two humans alive at the time, and that they knew each other/procreated together).

As a non-scientist I actually like the use of the terms mitochondrial Eve and Y-chromosomal Adam so long as they are properly explained. It needs to be made clear that there is no correlation with the Biblical Adam, we are referring to two specific lineages, and that "Adam" and "Eve" did not live at the same time. The problem is with the press who always tend to over-simplify everything.

On another matter why did this paper ignore the finding of haplogroup A00 published back in February this year in the American Journal of Human Genetics which places the root of the Y-tree at around 338,000 years ago?

http://www.cell.com/AJHG/abstract/S0002-9297(13)00073-6

The full text can be found here:

http://haplogroup-a.com/Ancient-Root-AJHG2013.pdf

While I have several reasons to disliking this analogy, I cannot fault the journalists completely for using it in this instance. Aside from my protests, there is no reason science journalists should think that it is a bad analogy, because it was used in the manuscript (without context or explanation).

Dogma has held that the common ancestor of human patrilineal lineages, popularly referred to as the Y-chromosome “Adam,” lived considerably more recently than the common ancestor of female lineages, the so-called mitochondrial “Eve.”

Why try to explain it in Biblical terms at all?

"Observations of the numbers of observed changes(mutations)" Thats the problem with the whole business here. Not misdirection of information.
These observations say nothing of what could of happened in the DNA . Its just a line of reasoning nothing did/could happen and so extrapolation backwards produces these results. I don't mean welcome mutations but other mechanisms to affect DNA change and so physical change.

Anyways this creationist sees this as a welcome new data. it does place generally the Adam near the Eve even with your time and place points.
It leads toward the idea of a first mand and woman from whence we all came. Thats the welcome thing creationists can rightly pick up on.
As long as they point out its coming from those with evolutionary presumptions and time presumptions.
It is probably a unwelcome fact to evolutionists dealing with the public on origin issues.

Same kind of confusion arises when one talks about the Higgs (God) particle and other instances in science where either the authors implicitly bring up the societal myths or journalists embelish the story/ies with their lack of scientific knowledge, hoping to sell more copy or thinking they're are simplifying the concept.

Thanks M. Wilson for the explanation. In my experience, the bad terminology does indeed create a lot of confusion, and it's frequently used by some creationist factions to argue for a literal Adam and Eve (much more frequently than some people here think). Dennis Venema, from the Biologos Foundation, explains the concepts very well with nice graphs, in the following article: Mitochondrial Eve, Y-Chromosome Adam, and Reasons to Believe. I hope that you make use of similar graphs in your upcoming video/series of articles. They are really helpful. I hope that you do a short review of the evidence for past population sizes as well.

I have a small question for you: Is there a way, based on the data available (or the data that might become available), to rule out that possibility that the mtDNA MRCA met with the Y chromosome MRCA? You don't have to answer that here. I hope that you throw some light on that in your upcoming articles. Thanks!

This is Rhazes again with a different account, sorry for the confusion. Can you please also comment on the main finding of the study? Was resolving the discrepancy really necessary or required in the first place, given our understanding of genetics and the human mating system? In other words, if it turns out that there's a real "discrepancy in time to common ancestor of males versus females", does that pose any theoretical problems? I remember watching an old video about the subject, and the explanation for the discrepancy that the presenter gives made sense to me. And the video is by the way a testimony to how confusing and misleading the terminology is. I hope that you comment on this point as well. Thanks!

There were several other genetic females living at the time of the person who carried the mtDNA ancestor of us all, and several other genetic males living at the same time as the genetic male who carried the Y chromosome ancestor of modern genetic males.

There were several thousand other genetic females living at the time of the person who carried the mtDNA ancestor of us all, and several thousand other genetic males living at the same time as the genetic male who carried the Y chromosome ancestor of modern genetic males.

A correction. The calculation I just gave was for a pair of Y lineages and a pair of mitochondrial lineages going back in time. But there would start out to be many more, and only back a ways would the ancestry thin out to a pair. So the calculation is more complex, but in any case the chance that "Eve" and "Adam" were a mated pair is very small, one part in tens of millions.

Question: Was there also an ancient 'Australopithecus Adam and Eve', a 'Lemur Adam and Eve', a 'Lobed Finned Fish Adam and Eve', etc.?

Most eukaryotes (and all multicellular organisms) have mitochondria. For those that also have a Y chromosome that is (mostly) not recombining with the X chromosome, there would be a mitochondrial Eve and a Y chromosome Adam.

But it goes further than that. We have a similar coalescent ancestor for every small piece of our genomes. However they are randomly either females or males, since those lineages go back through both males and females. Thus we have Cytochrome C Sam, Hemoglobin Beta Harriet, and a host of others, maybe 100,000 of them in all. Most of those are hundreds of thousands of years earlier than "Adam" and "Eve", as autosomal genes coalesce four times as slowly as Y's or mitochondria. So Malate Dehydrogenase Molly was possibly not a Homo sapiens.

And the lungfish and fungi also each have their multitude of coalescent ancestors of different parts of their genome.

We should give names to all the original ancestors of each chromosome, chosen to correct this misunderstanding.

For example, chromosome 2 is a fusion of ape chromosomes 2a and 2b. So we should give the ancestors of those two chromosomes names like Bonzo and Curious George.

"Steve" should be the official name of the ancestor of a chromosome; let's say chromosome 3. Let's make the religious right talk about how we all come from Adam and Steve.

If you don't know the gender of the ancestor, give them gender neutral names like Tracy.

We should pick some names from other mythologies and cultures, e.g. the ancestor of all Chinese is the Yellow Emperor, etc.

According to Wikipedia, "Y-chromosomal Aaron is the name given to the hypothesised most recent common ancestor of many of the patrilineal Jewish priestly caste known as Kohanim".

diogeneslamp0 said: We should give names to all the original ancestors of each chromosome, chosen to correct this misunderstanding. For example, chromosome 2 is a fusion of ape chromosomes 2a and 2b. So we should give the ancestors of those two chromosomes names like Bonzo and Curious George. "Steve" should be the official name of the ancestor of a chromosome; let's say chromosome 3. Let's make the religious right talk about how we all come from Adam and Steve. If you don't know the gender of the ancestor, give them gender neutral names like Tracy. We should pick some names from other mythologies and cultures, e.g. the ancestor of all Chinese is the Yellow Emperor, etc.

Nope. Sorry. Not buying it. Heuristic hyarchical clustering algorithms that work down to one individual have assumptions built in. Still makes more sense that a homogeneous population was being evolved than the entire human race coming from one extremely narrow bottleneck. What am I missing?

Some in the Citizen Genetic Genealogy community actually prefer
working with either Y-DNA - mtDNA - or both versus Autosomal DNA.

And yes, we are not some kooks wanting to trace our lineages back to
a putative 'Y-DNA Adam" or a 'mtDNA Eve' a couple hundred thousand years back.
Most of us happy getting back 500 to 700 YBP to the 1300s and 1400s.

A case in point is Dr. John Ashdown-Hill who went back 17 generations
to the Ibsen family to locate a mtDNA J1c2c with King Richard III who died in 1485. Ashdown-Hill is a professional freelance historian and a remarkable Citizen Genetic Genealogist.
However, the University of Leicester is embarked on a PR campaign
to airbrush Dr. John Ashdown-Hill out of the picture and to give near 100%
of the credit to the university geneticist, Dr. Turi King, as well as others at the university.
see: http://www.thisisleicestershire.co.uk/Richard-III-Historian-claims-airbrushed-king/story-19618285-detail/story.html#axzz2bJvIkPSF
see: http://en.wikipedia.org/wiki/Exhumation_of_Richard_III_of_England

Now, we have persons such as Razib Khan at the Gene Expression blog saying:
Please ignore mtDNA and Y chromosomal haplogroups
http://blogs.discovermagazine.com/gnxp/2013/05/please-ignore-mtdna-and-y-chromosomal-haplogroups/#.UgK1w5K1GAA

"This is a public service announcement. If you are a user of direct-to-consumer personal genomics services, please do not pay any attention to your mtDNA and Y chromosomal haplogroups." "What you should pay attention to are your autosomal results"

Khan also supports the views of Dr. Mark Thomas who refers to Citizen Genetic Genealogists as "Genetic Astrologers"

Khan is an outspoken and often incompetent antagonist to Consumer Genetic Genealogists. He fancies himself as knowing a little about everything when the cold hard facts that he mainly parrots the works of others and spouts off his widly conservative views.

So, I hope that the Pandas Thumb blogger will support the works of Citizen Genetic Genealogists and offer constructive comments on how we can up our game.

https://www.google.com/accounts/o8/id?id=AItOawmErg_OqK67w5rPGhjB84z7Qc2Onc5o5QY said: Nope. Sorry. Not buying it. Heuristic hyarchical clustering algorithms that work down to one individual have assumptions built in. Still makes more sense that a homogeneous population was being evolved than the entire human race coming from one extremely narrow bottleneck. What am I missing?

I agree: what does it mean that "a homogenous population was being evolved"?

As far as the efforts of people to trace ancestry through Y and mitochondria, what is the objective? The rest of their genes come from lots of sources.

I wonder what one gets from knowing that a Famous Person had my Y chromosome. Suppose mine was identical to Richard III's. Good conversation, but so what? Are those 13 protein coding loci giving us important insight into my imperious behavior?

The usefulness of any of these coalescent studies is much less in the specific genealogy, than it is in insights it gives into past population sizes, migration rates, mutation rates, population growth rates, and recombination rates. Particular genealogies will vary enormously from one region of the genome to another, and also be hard to infer precisely. But we can use Markov Chain Monte Carlo sampling to average information over our uncertainty about the genealogy, and accumulate information about those genetic parameters and population parameters. Knowing that I am the 28th-removed grandnephew of Count Otto the Gross is much less useful.

I think this stems from the bad analogy. As others have pointed out, we can trace back to the shared ancestor of any genomic region (we might have to get smaller and smaller on the autosomes), but there is no one person whose genome was the ancestor of all of the chromosomes (1-22), X, and either mtDNA or Y.

I think it's as was already said above - once a term is established in popular usage, it ain't gonna change because somebody thinks that's the thing to do.

Language isn't intelligently designed, either. (As long as nobody mentions "Esperanto", anyway... :D ).

Then there's the "Big Bang"...

I note that somebody already mentioned "God particle" above.

Henry

Alright. I'm feeling really dense here. But I'm a computer science guy, so I'm used to that feeling. I worked hard to get to the AHA(!) point that populations evolve, not individuals, and that evolution and speciation "events" are like the threads of a slow river meandering through a flood plain, splitting, combining, and splitting again until eventually finding separate courses. So, what's with this whole mitochondrial Eve thing? Is this notion really saying that all living women descended from a single human female? I get the idea that "mtDNA Eve" lived in a group of people, and the idea that if you trace things back you get to a single ancestor. But isn't that "single ancestor" way, waaay, waaaaaay before the first mammal, let alone the first hominid? If Eve lived among a group of people, did all those other women contribute nothing to the gene pool? All those other lineages simply died out? People are talking like this whole notion is completely obvious. I don't see how it's "obvious".

What am I missing?

Scott F said: Is this notion really saying that all living women descended from a single human female? I get the idea that "mtDNA Eve" lived in a group of people, and the idea that if you trace things back you get to a single ancestor. But isn't that "single ancestor" way, waaay, waaaaaay before the first mammal, let alone the first hominid? If Eve lived among a group of people, did all those other women contribute nothing to the gene pool? All those other lineages simply died out?

Scott F said: What am I missing?

https://www.google.com/accounts/o8/id?id=AItOawmErg_OqK67w5rPGhjB84z7Qc2Onc5o5QY said: Nope. Sorry. Not buying it. Heuristic hyarchical clustering algorithms that work down to one individual have assumptions built in. Still makes more sense that a homogeneous population was being evolved than the entire human race coming from one extremely narrow bottleneck. What am I missing?

Does this mean the Y chromosome (and only the Y chromosome) of everybody alive today has descended from a single individual that lived 120K-156K years ago; but we share other chromosomes contributed by others in that ancient population?

And similarly for the mitochondrial DNA?

I think I understand the sources of confusion here thanks to the post, but I am wondering what the larger point or lesson of this research is. What does finding the LCA of a particular piece of genome tell us? Why is it important to find the Adam and Eve of these particular bits of DNA, if as it seems they are selected for ease of tracing?

Hmm... Okay. So, the "Y Adam" and the "mtDNA Eve" are different individuals at different points in time, because you are not talking about the single ancestor of all men or all women. You're talking about the single ancestor of just one piece of the DNA. Another example one might pick is the Human Chromosome-2 fusion. It seems to me most likely that such a fusion event could have happened in exactly that way only once. For a period of time, the fused chromosome could still viably interbreed (if that's the right notion) with the rest of the ancestral population, enough so that this chromosome mutation spread to the rest of the population. And it didn't have to spread to all of the population, just the part that eventually split to become "human". But this means that there was one individual who was the ancestor of the chromosome-2 fusion site that everyone now carries.

Is that the idea?

Carrying the "river" analogy further, and mixing metaphors, if the evolving population is the branching river, one could imagine the river as made up of lots of individual threads, each thread representing a gene, or some distinct characteristic of the DNA. If one were to try and follow one of these threads, you would follow a particular path through the streams and tributaries of the branching river. If you were to then follow a different thread, it would follow a different path through the historical waters.

Then, each individual is at a particular fixed point in the river, and each individual represents a particular bundle of these threads at a particular point in time. Each thread can be followed (conceptually) through different sets of individuals. No single individual would ever contain all the possible threads (unless there really was a single, historical "Adam", or "Noah"), even though a single individual thread must have had its start inside one individual.

This, I think, directly addresses the question of, "How did the first male with mutations WXYZ meet up with the first female with mutations WXYZ?" It's a different perspective on how a single mutation can spread through a population. If you start with a single spontaneous mutation, it's not too difficult to grasp the concept that it could spread through the rest of the population (through genetic drift, if nothing else), even if that exact same mutation never spontaneously appeared in any other unrelated individual. But turn that around, look at it from the other direction of time, and it's more difficult to imagine that some mutation that everyone shares (is it really a "mutation" if everyone has it?) must have originated with a single individual.

Even if all that were "true" in some metaphorical sense, it only helps understand the "Y Adam". It doesn't help as much with the "mtDNA Eve". Unlike the rest of the genes (including the "Y"), the mitochondrial "clump" of DNA doesn't "mix". Wouldn't the least-common-ancestor of the mitochondria be the first eukaryote to swallow the first proteobacteria? Isn't that the point where that particular "thread" started? If the other females at the time contributed any genetic material to today's population, they must also have contributed their particular version of the mitochondria. Mustn't they?

Scott F said: Even if all that were "true" in some metaphorical sense, it only helps understand the "Y Adam". It doesn't help as much with the "mtDNA Eve". Unlike the rest of the genes (including the "Y"), the mitochondrial "clump" of DNA doesn't "mix". Wouldn't the least-common-ancestor of the mitochondria be the first eukaryote to swallow the first proteobacteria? Isn't that the point where that particular "thread" started? If the other females at the time contributed any genetic material to today's population, they must also have contributed their particular version of the mitochondria. Mustn't they?

david.eugene.carlson said:

https://www.google.com/accounts/o8/id?id=AItOawmErg_OqK67w5rPGhjB84z7Qc2Onc5o5QY said: Nope. Sorry. Not buying it. Heuristic hyarchical clustering algorithms that work down to one individual have assumptions built in. Still makes more sense that a homogeneous population was being evolved than the entire human race coming from one extremely narrow bottleneck. What am I missing?

What is it that you're not buying? The existence of a most recent common mitochondrial genome or Y-chromosome ancestor is simply a by-product of genealogical descent. AFAIK, these concepts do not suggest that the current mitochondrial "eve" lived during an extreme bottleneck. In all likelihood, this individual (or more specifically, her mitochondria) was a member of a much larger population.

For more about the ancestral mtDNA see part 2 here:

http://pandasthumb.org/archives/2013/08/y-and-mtdna-are-1.html

W. H. Heydt said: IANAB... I think of it this way... You have a population of many females. Each will pass her unique version of mtDNA to her children. Allowing for mutations, her female children will pass their versions all to their children. Not all females will have children, and of those that do, not all will have female children. Over time, any unique lineage of mtDNA can go extinct. Eventually, you will get a branching tree structure of related patterns of mtDNA traceable back to a single ancestral form. The earliest ancestress of the remaining traceable form becomes the "mtDNA Eve". As various modern lineages of mtDNA go extinct, the "mtDNA Eve" will change. Some one with good biological chops will be able to tell if I've got the concept down reasonably correctly for a layman.

harold said:

https://www.google.com/accounts/o8/id?id=AItOawmErg_OqK67w5rPGhjB84z7Qc2Onc5o5QY said: Nope. Sorry. Not buying it. Heuristic hyarchical clustering algorithms that work down to one individual have assumptions built in. Still makes more sense that a homogeneous population was being evolved than the entire human race coming from one extremely narrow bottleneck. What am I missing?

Of course, I could be wrong - maybe the writer will clarify with a reasoned response.) Having said that, discussion of the most recent common ancestor of a gene does imply, not assumptions, but operational definitions.

https://www.google.com/accounts/o8/id?id=AItOawmErg_OqK67w5rPGhjB84z7Qc2Onc5o5QY said: Nope. Sorry. Not buying it. Heuristic hyarchical clustering algorithms that work down to one individual have assumptions built in. Still makes more sense that a homogeneous population was being evolved than the entire human race coming from one extremely narrow bottleneck. What am I missing?

W. H. Heydt said:

Scott F said: Even if all that were "true" in some metaphorical sense, it only helps understand the "Y Adam". It doesn't help as much with the "mtDNA Eve". Unlike the rest of the genes (including the "Y"), the mitochondrial "clump" of DNA doesn't "mix". Wouldn't the least-common-ancestor of the mitochondria be the first eukaryote to swallow the first proteobacteria? Isn't that the point where that particular "thread" started? If the other females at the time contributed any genetic material to today's population, they must also have contributed their particular version of the mitochondria. Mustn't they?

IANAB... I think of it this way... You have a population of many females. Each will pass her unique version of mtDNA to her children. Allowing for mutations, her female children will pass their versions all to their children. Not all females will have children, and of those that do, not all will have female children. Over time, any unique lineage of mtDNA can go extinct. Eventually, you will get a branching tree structure of related patterns of mtDNA traceable back to a single ancestral form. The earliest ancestress of the remaining traceable form becomes the "mtDNA Eve". As various modern lineages of mtDNA go extinct, the "mtDNA Eve" will change. Some one with good biological chops will be able to tell if I've got the concept down reasonably correctly for a layman.

Scott F said: (Maybe Part #2 will cover this, but I have to respond here first.) I understand the part about the branching tree structure, and various "modern" lineages of mtDNA going extinct. But we have declared we've found the LCA of *all* "current" lineages. There is no other. Sure, other more recent lineages might go extinct, but once the progeny of the LCA have replaced all others, the LCA no longer changes. Right? Or am I missing something again? Let me read Part #2.

There were several other genetic females living at the time of the person who carried the mtDNA ancestor of us all, and several other genetic males living at the same time as the genetic male who carried the Y chromosome ancestor of modern genetic males.

— M. Wilson Sayres

Eric Finn said: I understand the part about the branching tree structure, and various "modern" lineages of mtDNA going extinct. But we have declared we've found the LCA of *all* "current" lineages. There is no other. Sure, other more recent lineages might go extinct, but once the progeny of the LCA have replaced all others, the LCA no longer changes. Right? Or am I missing something again?

I hope you won’t mind me interfering. Assume we see features that are denoted using letters in the alphabet. Many of the letters are in use in forming combinations such as ABCHKT and ABCLMT. Assume further that ABC is part of any combination we can find. Thus, it defines a common property shared by everyone now living. The last common ancestor is then defined as ... Well, how is the LCA defined ? It can’t be the first occurrence of ABC in the combination. Or can it ? Could LCA be an individual from the first era that everyone had this part in their combinations ? I suddenly realise that I don’t understand what this topic is all about. Anyway, assume the feature C is somehow mutated. Then the common part would be AB only. Surely, I presume, the LCA would be different (and maybe was living a longer time ago than the LCA for the ABC). We can also think (in mathematical speculations) that a different part of the combinations, let’s say ABE, would become the part that is shared by everyone. Again, the LCA would change. The LCA for ABE is different from the LCAs for ABC and AB. It might be the most recent of them all, but not necessarily. It depends also on the definition of the LCA. I admit that I am confused. A little bit of help would be appreciated.

Scott F said: (Maybe Part #2 will cover this, but I have to respond here first.) I understand the part about the branching tree structure, and various "modern" lineages of mtDNA going extinct. But we have declared we've found the LCA of *all* "current" lineages. There is no other. Sure, other more recent lineages might go extinct, but once the progeny of the LCA have replaced all others, the LCA no longer changes. Right? Or am I missing something again? Let me read Part #2.

W. H. Heydt said: If one goes from an LCA with an "ABC" sequence to an LCA with an "AB" sequence, the "new" LCA would have be further back in time. That is, when was the last time that those sequences--for all existing modern lineages--were connected on the pruned, branching descent tree? Attenion: Biologist on aisle 3, please...

Eric Finn said:

The question is: How was the knowledge about modern genomes used to estimate the time to the most recent ancestor?

I plan to cover this in a future post (they are coming, but there will probably only be one this coming week, y'know, with my day job and all). A quick response for now. From the Poznik paper (and hopefully someone will correct me if I've misunderstood: TMRCA = (Average number of differences observed in the genomic region of interest across all individuals reconstructed ancestor)/(Mutation rate for genomic region of interest) The units: Years = Mutations/(Mutations/Year) Is this what you were looking for?

M. Wilson Sayres said:

Matt Young said: It seems to me that Y-chromosomal Adam is not Adam at all but Noah. Noah is the last common ancestor of all living males (according to the myth), not Adam.

Matt, I'm confused. Why try to explain it in Biblical terms at all?

M. Wilson Sayres said: I plan to cover this in a future post (they are coming, but there will probably only be one this coming week, y'know, with my day job and all). A quick response for now. From the Poznik paper (and hopefully someone will correct me if I've misunderstood: TMRCA = (Average number of differences observed in the genomic region of interest across all individuals reconstructed ancestor)/(Mutation rate for genomic region of interest) The units: Years = Mutations/(Mutations/Year) Is this what you were looking for?