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Author Topic:   All Human Beings Are Descendants of Adam
Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 25 of 118 (606412)
02-25-2011 10:47 AM
Reply to: Message 19 by Europa
02-25-2011 9:55 AM


Even though I'm not Dr. A.
Is it (theoretically) possible to have two MEs even though we are all a single species?
I'm going to slightly disagree with Mr. Jack here and say that we could but not at the same time. The coalescence for Mitochondrial eve is around ~170,000 years based on the distribution of modern mitochondrial genotypes, if we were able to go in a time machine back a few 10's of thousands of years and do a similar experiment with that population of humans we might identify a different mitochondrial eve at a different coalescence point. Although as Mr. Jack points out, at some point that ancestor is not themselves going to be of the species Homo sapiens sapiens
By definition any given population can only have 1 mitochondrial eve at a time since the whole point is that ME is the common matrilineal ancestor, if there is more than one candidate genome then you haven't gone back far enough and aren't looking at the common ancestor.
The human race could even have a different mitochondrial eve in the future since novel mitochondrial genotypes are being produced all the time and in the right circumstances one of these could reach fixation.
There is a simulation on a site hosted by the North Carolina state university showing how a mixture of maternal mitochondrial genotypes resolve down to one as the result of random sampling.
TTFN,
WK
Edited by Wounded King, : No reason given.

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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 31 of 118 (606528)
02-26-2011 4:11 AM
Reply to: Message 29 by NoNukes
02-25-2011 10:44 PM


She is instead our most recent common ancestor.
No, she isn't, she is our most recent matrilineal common ancestor, thats a pretty important distinction to bear in mind. The actual most recent common ancestor is probably much more recent, possibly only a few thousand years ago (Rhode et al., 2004; Lachance, 2009).
TTFN,
WK

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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 41 of 118 (606730)
02-28-2011 4:28 AM
Reply to: Message 40 by Phage0070
02-27-2011 3:10 PM


I may be wrong but my understanding of evolution does not contradict the statement: "All human beings are descendants of Adam."
You could be right if you said "all of the current human population", going back a few thousand years you reach a point where a high proportion of the entire human population are all common ancestors of the current population. For humans of European ancestry this has been calculated to be as recent as 800AD, but for the whole of humanity it would be earlier though most models suggest dates between 150BC and 800AD. This isn't based on genetic data but simply on mathematical population models.
There might well have been someone around at that time, amidst the thousands of contemporaneous common ancestors, who was called Adam and of whom we are all descendants.
TTFN,
WK
*ABE* Oops, I replied to Phage0070 by mistake instead of Europa.
Edited by Wounded King, : No reason given.

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 Message 44 by Phage0070, posted 02-28-2011 10:29 AM Wounded King has replied

  
Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 46 of 118 (606782)
02-28-2011 11:11 AM
Reply to: Message 44 by Phage0070
02-28-2011 10:29 AM


the population models are bunk.
I'm not sure what you mean by this? What part of the population models on which recent MRCA estimates are based do you disagree with? That people have 2 parents? That they have 4 grandparents? That in the past the human population of the Earth has been considerably smaller than it is currently?
Whatever models you are talking about they don't seem to be ones having anything to do with common ancestry.
TTFN,
WK

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 Message 47 by Phage0070, posted 02-28-2011 11:34 AM Wounded King has replied

  
Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 49 of 118 (606796)
02-28-2011 12:12 PM
Reply to: Message 47 by Phage0070
02-28-2011 11:34 AM


the idea that the entirety of humanity is descended from two individuals from such recent a pairing is patently ridiculous.
Solely, you need to put 'solely' or 'just' in their somewhere because the entirety of humanity is descended from two individuals from such a recent pairing as well as from another few million other such pairings around the same time.
TTFN,
WK

This message is a reply to:
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 Message 50 by Phage0070, posted 02-28-2011 12:21 PM Wounded King has replied

  
Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 55 of 118 (606827)
02-28-2011 1:56 PM
Reply to: Message 50 by Phage0070
02-28-2011 12:21 PM


OK true, but you wouldn't parse the statement "Humanity is descended from Adam" to mean that there is at least one living human alive today that descended from someone named Adam, and the rest of humanity is composed of offspring from other family lines.
You still don't seem to get it, everyone alive today is descended from all of that ancestral population, there are no 'other family lines'. There is a historical point where there are 2 populations one consists of people who have no extant modern descendants and the other consists of people all of whom are ancestral to every extant modern human. This is called the identical ancestors point. In fact looking at that I seem to have got the numbers for the MRCA and the IAP mixed up, with the IAP being several thousand years before the MRCA.
If we are to use such a tortured interpretation then we can conclude that the original statement was technically true but mostly meaningless.
Since Europa seems willing to consider a 'hypothetical Adam' that is how I view it.
TTFN,
WK

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 Message 58 by Europa, posted 02-28-2011 11:48 PM Wounded King has replied

  
Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 62 of 118 (606931)
03-01-2011 4:07 AM
Reply to: Message 58 by Europa
02-28-2011 11:48 PM


If we are descendants of an ancestral population, why do we ALL have the traits that could "trace" our family line to one single being?
Well we don't have 'The traits', as should be obvious now, we have mitochondrial traits which can be trace back to ME, men have y chromosomal traits that can be traced back to YA. In theory we could do this for any discrete genetic trait and they would probably identify lots of different MRCAs for each trait, because sexual mixing would confuse the lineage of the traits and some ancestral traits will be lost entirely. All of these estimates will give us dates much further back than that of our actual MRCA, and it is perfectly possible that many people will have absolutely no genetic contribution from that MRCA even though they are descended from them.
Why don't we have a mixture of traits that would tell us our great, great, ... great grandmothers were different people?
Because, as I just told you in the last post, they weren't. When you get to you Great-great ... etc. grandparents they were all the same people, that is the entire point of the Identical Ancestors Point. As we go further back in time every modern day individual has an increasing pool of ancestors and the world population gets smaller. A natural consequence of this is that at some point the ancestral pool for everyone alive today will overlap 100%.
If we go down a few great's to more recently however then of course we can discriminate different lineages, we do it all the time in genetic analyses. If we couldn't then how would genetic fingerprinting work? Or haplotype mapping.
Could this be because we have not tested for other family lines?
No, the IAP is a direct consequence of population growth and the nature of human reproduction. We need 2 parents to be born, who themselves needed 2 parents to be born and going back far enough we all needed exactly the same large set of ancestors to be born.
Or could this be because there really aren't other family lines?
Exactly, but this doesn't mean there never were simply that there aren't now, the other lines went extinct, similarly if we went a couple of thousand years into the future all of these things might have changed with a different ME, YA, MRCA and IAP having been established. This is because all of these things are determined retrospectively based on the constitution of a given population and a future population will have a different constitution to the current one.
TTFN,
WK

This message is a reply to:
 Message 58 by Europa, posted 02-28-2011 11:48 PM Europa has replied

Replies to this message:
 Message 64 by Blue Jay, posted 03-01-2011 9:44 AM Wounded King has replied
 Message 66 by Europa, posted 03-01-2011 1:26 PM Wounded King has replied

  
Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 63 of 118 (606933)
03-01-2011 4:25 AM
Reply to: Message 61 by dennis780
03-01-2011 4:03 AM


However, you can quite easily use those models to argue that humans have NOT been in existance for millions of years, as suggested by evolutionary teaching.
No you can't. People who don't understand populations biology or genetics can apply simplistic mathematical models that they believe show this, but only because they aren't bothered by such trivialities as having their models bear any resemblance to reality.
This is a fair arguement, with logical and documented evidence.
Wow, you just saying that totally convinced me, hallelujah, praise the lord.
Can someone point me to the graphs everyone is speaking of?
Are you sure you are on the right thread? You are the first person here to mention graphs.
TTFN,
WK

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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 65 of 118 (606983)
03-01-2011 10:56 AM
Reply to: Message 64 by Blue Jay
03-01-2011 9:44 AM


In meiosis chromosomes segregate on the basis of random assortment. So in theory it is possible for an organism to produce a gamete only having genetic material from one of its parents. This is extreme and almost certainly never happens but the random assortment of chromosomes during meiosis does mean that genetic material from some ancestors is continually being lost in different lineages. Other factors mitigate this such as crossing over but the principle still stands.
For a more detailed analysis see this page.
TTFN,
WK
Edited by Wounded King, : Changed 'zygote' to 'gamete'

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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 67 of 118 (607049)
03-01-2011 3:26 PM
Reply to: Message 66 by Europa
03-01-2011 1:26 PM


But, do you think we are assuming that it will overlap 100 percent?
Only in as much as we assume that 2+2=4 and that most people have 2 parents. This isn't something highly theoretical and speculative, it is a natural consequence of sexual reproduction and what we know about historical global population levels.
What would be the difference we should expect to see in our population of today?
Well if we started off with 10 Adams or 10 Eves then there wouldn't be a human population. Beyond that the question s too vague to answer, it is highly dependent on when this founder population is proposed to have existed.
This is a little different question. But would like to know your views on this.
Do you think primate to human change was a catapulted change?
I mean a macro-mutation sort of a change?
Macro-mutation isn't a term in much common usage in modern evolutionary biology. This is principally because with an improving knowledge of genetics, particularly developmental genetics, it has become clear that small genetic changes can have substantial, what might be considered macro, morpholgical/phenotypic effects.
I certainly don't think there is any reason to think that the divergence between humans and chimps, for example, would have been a dramatic evolutionary jump except perhaps in the longest geological time scales.
There was an extensive thread a while ago about reconciling observed mutation rates with the degree of genetic divergence between humans and chimps and the estimates of when the split occurred. The rates and estimates seem to be compatible.
TTFN,
WK

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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 69 of 118 (607055)
03-01-2011 4:25 PM
Reply to: Message 68 by Taq
03-01-2011 3:50 PM


Thanks for the correction
You're right, sorry about that, I meant gamete.
For 23 pairs of chromosomes the chances of this occurring are 1 in 2^23 or about 1 in 8 million. It is the same odds of flipping tails 23 times in a row.
Sure, but there are billions of people on the planet and the further back up the ancestral chain you go the lower the numbers get, until at some point they are a virtual certainty.
For great grand parents the page I referenced before calculates it as 1 in 747 without taking account of crossing over.
Even when you factor in crossing over the numbers are still inevitable after about 10 to 20 generations.
TTFN,
WK
Edited by Wounded King, : No reason given.

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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 72 of 118 (607110)
03-02-2011 4:08 AM
Reply to: Message 71 by Dr Jack
03-02-2011 3:58 AM


It's worse than that, because chromosomes undergo crossing-over during meiosis so chromosomes inherited from both parent are mixed together before being passed on.
The article I linked to upthread puts that figure at 1 in 70 trillion with crossing-over.
TTFN,
WK

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 Message 71 by Dr Jack, posted 03-02-2011 3:58 AM Dr Jack has replied

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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 74 of 118 (609401)
03-19-2011 10:07 AM


Bump for Europa
I'm just bumping this thread since Europa seems to be effectively trying to open another one on pretty much the same subject. In fact I don't see why any of the questions in the new thread wouldn't be appropriate here, indeed we have effectively already answered most of them here. I'm wondering why Europa wants a new thread for us to rehash exactly the same explanations.
TTFN,
WK

Replies to this message:
 Message 75 by ICANT, posted 03-19-2011 8:47 PM Wounded King has replied

  
Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 77 of 118 (609436)
03-20-2011 6:23 AM
Reply to: Message 75 by ICANT
03-19-2011 8:47 PM


Re: Bump for Europa
So if there was many people in existence at this time and then their descendants were all destroyed but 4 men and 4 women 2k years later. Could this produce the most recent descendant of living mankind as well as the diversity we see today?
Not unless genetics and population dynamics were radically different for the subsequent thousands of years and then became what we observe today.
If there was as extreme a bottleneck as only 4 mating pairs then given observed mutation rates we certainly wouldn't expect to see the diversity we do in human populations.
Also molecular estimates of most recent common ancestors for a wide variety of genes, not to mention mitochondrial and Y-chromosomes, should all coalesce much more tightly on whenever this post-flood founding event was, instead of giving us widely divergent ranges over several tens of thousands of years.
No matter how large an initial created event was the extreme bottleneck of the flood would obliterate whatever genetic diversity it represented. This is especially true since the couples all contained members of the same family so the genetic variability would be even further reduced.
TTFN,
WK

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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 79 of 118 (609889)
03-24-2011 8:58 AM
Reply to: Message 78 by Europa
03-24-2011 7:35 AM


Re: Becoming Human
According to this theory, there was no first human being.
I'm not sure this is really the case, provided we had a clear enough definition of human being then there probably would have been an identifiable first organism to fit that criteria, but it probably wouldn't have been readily distinguishable from all of its contemporaries in the same pre-human hominid population.
Isn't this an anti-thesis?
No.
On the one hand we are saying that there was no first human being. On the other hand we are saying that we are all descendants of a single human being -- Mitochondrial Eve (ME).
Those things are completely unrelated. As has been pointed out to you several times already in this thread Mitochondrial eve and Y-chromosome Adam and all the other most recent common ancestor estimates are, and the clue was in the name, about most recent common ancestors, not about first ancestors. Also ME doesn't say that we are only descended from 1 single human being. As has, again, already been pointed out in this thread there is a point not too far back in history, only a matter of a few thousand years, you will find that all modern humans share exactly the same set of multiple ancestors, we are all commonly descended from all of them, just as much as we are all commonly descended from ME.
Presently, ME is explained by saying the human population faced a bottleneck sometime in the past and that is why we have ME.
Again this has already been contradicted in this thread, the existence of a mitochondrial eve is simply a product of mitochondrial inheritance and population dynamics. The bottleneck is considered the reason why our estimates for ME are for a particular time, but there would still be an ME without the bottleneck it would probably just be a different individual from an earlier time.
We know that ME existed, but we do not know anything about the others during her time.
This is not true, we can't know what their mitochondrial genotype was because that has been lost, but other than that there is plenty we can know.
So, instead of saying ME had companions, why don't we say we do not know whether ME had companions?
Because it wouldn't be true. the MRCA calculations for various other genetic markers extend back well beyond ME, so we know there was a larger population of which ME was just one individual.
But, because we have someone like ME, I think it favours the theory that we are descendants of a single human being.
That is apparently because you still don't understand it. We are all the descendants of a whole lot of single human beings. There are lots of individual humans back through history from whom all of today's population is descended, ME is just one of them.
Why then is the theory of bottlenecking more plausible than the theory that we descended from a single human being?
Because there are multiple lines of genetic evidence which support that theory and none which support your barely coherent alternative. You keep pussy footing around saying you aren't talking about the biblical Adam or the Biblical eve, so then what are you talking about as a scenario for every body being descended from 1 individual, how would that even work? Were they a hermaphrodite? It really does sound like you just mean the biblical scenario of one original breeding pair alone giving rise to every subsequent person in the whole human race.
I am just trying to make sense of the little I know about evolution of human beings.
It is hard to believe this when you appear to have totally failed to make the effort to understand any of the answers already provided to you and just asked all the same questions again.
TTFN,
WK

This message is a reply to:
 Message 78 by Europa, posted 03-24-2011 7:35 AM Europa has replied

Replies to this message:
 Message 87 by Europa, posted 03-26-2011 5:14 AM Wounded King has replied

  
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