Question about evolution, genetic bottlenecks, and inbreeding

Yeah I didnt think you could

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We have more than one ancestor.

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We have at least one MRCA.

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We may have more than one MRCA.

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The definition of MRCA is THE MOST RECENT COMMON ANCESTOR.

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Oh, you believe me now?

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You clearly take me for an idiot and have not been reading any of my posts.I have repeatedly stated it is the most recent common ancestor. Yuo say you have not memorised my posts word for word, you have not even read the basic points of them either.

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Bet?

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Look once more at the diagram from the SkepticWiki. Individuals A through H are all contemporaries, and all common ancestors of the present generation.

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Your argument cannot be "logically inevitable" if it is possible to conceive of a counterexample. And that is a counterexample.

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THIS IS NOTHING TO DO WITH THAT DIAGRAM. I HAVE NOW SAID REPEATEDLY, IAM NOT REFFERING TO GRANDPARENT MODELS ETC I AM TALKING ABOUT MRCA'S FOR GEOGRAPHICALLY DIVIDED POPULATIONS OR WHOLE SPECIES

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How would I know?

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Go back, re read everything I have said, then answer the question on what you think is the most likely answer to this questionDo we have a single MRCA that is related both chimpanzees and humans, yes or no?

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Can we confirm there must a single most recent individual common ancestor to all humans? Or do we disagree on that to?

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I don't think that there is anything that rules out multiple common ancestors in that generation.

The answer to this question is bleedingly obvious. Say that chimp and human share a common gene A, there was a common individual ancestor for the particular gene A. Say there was another gene B that we both share. There was another common individual ancestor for the particular gene B. Surely, gene A alone does not define a human or a chimp. Neither is gene B alone.

To what verb is "could" an auxiliary? You seemed to be in some doubt in post #46. Now imagine that individuals S, T, U and V go off and live on an island, and W, X, Y and Z stay on the mainland. Then their descendants diverge genetically so much that they speciate.Where is the unique MRCA of the two resulting geographically divided species? They don't have one, do they? If you are now asking me which is most likely, does that mean that you concede that both are possible?I haven't figured out which is the most likely. If you believe that you have, please show your working. All I have maintained is that both are possible.

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How would I know?

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Oh, are you trying to set us up here? Trying to worm around to some sort of creationist or ID bs.

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You to have clearly not read a thing I have said. Some of you are actually as bad as some of the creationists I have been harassing these past months.

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How would I know?

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Ok, I guess you guys are never going to trust me, so unless some one wants to play my logic game, and let me explain my line of reasoning literally step by step by answering the question'do chimps and humans have one single Most recent common ancestor?'In the mean time, I really do recommend you pick up the the Ancestor's tale by Richard Dawkins it is an excellent book and it where i am getting my argument from. I have also read River out of Eden if you want to pick that up to.In the mean time I will let you mull over this. If you dont believe Dawkins on evolution, you sure as heck will not believe me:Any set of us must converge upon A SINGLE CONCESTOR (or couple(me: I'll let that slide for now, I am argueing that if we go further back it is one, still Dawkins is limiting the number to two,))...Where we can start looking for Concestor 0, THE most recent ancestor of surviving humans.The graph chart on page 39 is also clear in reffering to a single person.1:
If anyone here thinks i am a liar or a creationist, I'd have to be the first one who has a gene centered view of evolution as a study of Dawkins.2:
I came on this forum asking how we can be descended from one ancestor and avoid the problem of inbreeding, that question has been answered for me, and then I find people trying to say that we dont only have one most recent.So if anyone will let me, I will explain to them my line of reasoning, but i am really only good at this if I can ask questions, and the questions be answered, as it ensures you yourself are whittling down the possibilites.Then once it is explained, you can take it or leave it.So for anyone who is interested, once again:'do chimps and humans have one single Most recent common ancestor?'You dont even need to go back and re-read my posts.

This has everything to do with the diagram. Just like "macroevolution" is just "microevolution" taken over long periods of time, tracing lineages to the MRCA of an entire species is just tracing lineages of individual family trees over long periods of time. The diagram proves that no matter how far back you go, you always have a group of contemporaries all individual common ancestors of the population generations later.Yes, there was a single individual who was the common ancestor of individuals A and B many generations later. But the same thing can be said of many other individuals who contributed to the myriads of other genes inherited by A and B. By your approach, MRCA as an individual is meaningless because there were a kazillion MRCA's.

I lose, I throw in the towel.'We can trace multiple MCRA if we go back through different lines'I just cant comprehend why my books refer to a MRCA as an individual.Edited by harry, : No reason given.

There is only one MRCA (or possibly pair, if you using whole individuals) for a given group, but the MRCA will change for how you define the group. So, if we take as a group me and my cousins on my father's side, our MRCA pair is our grandmother and grandfather. This, of course does not mean that all our genes came from those grandparents, simple that those grandparents have contributed something in the DNA of each of us. However, if we start looking at individual genes, e.g. eye color, then that MRCA will mostly like be different for each gene or even each allele. This is why mitochondrial-Eve and Y-Adam probably lived generations apart. So yes, there can be kazillions of MRCAs if you look at it on a gene for gene basis. BUT, if you take each individual as a consensus of genes you can still find 1 single individual (or pair of individuals) that is the MRCA for a whole population.So to sum up: an MRCA for a population of individuals is the individual (or pair) that has contributed SOME DNA (regardless of which gene or set of genes) to every LIVING individual.An MRCA for a gene or set of related alleles is the individual who had an ancestral form of that gene or set of alleles from which all CURRENT (i.e. exist in living individuals) are derived.

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"There are three kinds of lies: lies, damned lies, and statistics."

Different lines? How else would you trace the MCRA?I hate to break this to you, but your genetic makeup is not entirely made up of genes contributed from your father. The MCRA of you and your sister (if you have one) include both your father and mother. Already, I've just proven that just taken one generation back you have multiple MCRA. If you want to take another generation back, the MCRA consisted of 4 individuals. No matter how far back you go, you're never going to find JUST ONE individual who was the sole MCRA.Now, if you want to take another route and say your MCRA for your Y chromosome, then yes the MCRA of your and your brother's Y chromosome is your father. Is this what you're trying to say?

great, now stagamancer has taken up what i abandoned. lol.I was looking from the individual perspective, not the genes.Staga how do you deal with the question of ifSTUV go live on an island and wxyz live on another, surely they have two sets of MRCA, namely the two central pairs in the 3rd generation.I

Taz, where on earht have i implied i thought all my genes came from my father. Stop putting words in my mouth. That does not effect my argument at all, because even though my genes come from my mother and father, their lineages will eventually coverge again because they are how ever distant cousins.Edited by harry, : No reason given.

This doesn't even make sense. MRCA stands for MOST RECENT Common Ancestor. So, for you and your sister, that answer is your parents. So yes, there are two there, but it's a mating pair. Your grandparents don't count because, while common ancestors, they are NOT MOST RECENT. However, think of this. If you have 1/2 siblings because your father has had two marriages (for whatever reason) then only your father is the MRCA for you and your 1/2 siblings. So yes OBVIOUSLY there can be more than one common ancestor, but there is only 1 individual or 1 mating pair that can be the MOST RECENT common ancestor.

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"There are three kinds of lies: lies, damned lies, and statistics."

And how exactly do you propose this population started out? Are we talking about a male figure with 20 wives isolated on an island?

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This doesn't even make sense. MRCA stands for MOST RECENT Common Ancestor. So, for you and your sister, that answer is your parents. So yes, there are two there, but it's a mating pair. Your grandparents don't count because, while common ancestors, they are NOT MOST RECENT. However, think of this. If you have 1/2 siblings because your father has had two marriages (for whatever reason) then only your father is the MRCA for you and your 1/2 siblings. So yes OBVIOUSLY there can be more than one common ancestor, but there is only 1 individual or 1 mating pair that can be the MOST RECENT common ancestor.

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Yes thankyou staga that is also what I was going to say. They are your ancestor but not your most recent. People keep saying I am talking about ancestor and I am not, I am talking about most recent.I am saying that on a species level, when a species divides, there must a be a single creature they are both descended from, but my whole problem i posted last that another poster gave has made me struggle.Edited by harry, : No reason given.

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And how exactly do you propose this population started out? Are we talking about a male figure with 20 wives isolated on an island?

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Refer to my chart on page 4, shows how one man can be the single anestor of everyone alive, despite having large numbers of people breed with his lineage.