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Author Topic:   All Human Beings Are Descendants of Adam
Coyote
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Posts: 5989
Joined: 01-12-2008
Member Rating: 3.5


Message 76 of 118 (609424)
03-19-2011 9:29 PM
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? Just asking.

No. Starting from about 4,350 years ago, there is no way to explain the diversity we see in either humans or the animal kingdom. It just doesn't work.


This message is a reply to:
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Wounded King
Member (Idle past 1627 days)
Posts: 4149
From: Edinburgh, Scotland
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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Europa
Member (Idle past 2219 days)
Posts: 68
Joined: 06-05-2010


Message 78 of 118 (609887)
03-24-2011 7:35 AM


Becoming Human
At one time, we were ape-like primates. We lived in the jungle, probably on trees. We became humans. Not overnight. But gradually, over millions of years. This is the accepted scientific theory about how human beings originated. According to this theory, there was no first human being. There was no Adam, nor Eve.

If you accept this to be true, how do you fit Mitochondrial Eve into the scenario?

Isn't this an anti-thesis? 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).

Presently, ME is explained by saying the human population faced a bottleneck sometime in the past and that is why we have ME. My question is why do we assume that we faced a bottleneck? We know that ME existed, but we do not know anything about the others during her time. So, instead of saying ME had companions, why don't we say we do not know whether ME had companions?

I am not saying that ME is the Bilical Eve. But, because we have someone like ME, I think it favours the theory that we are descendants of a single human being. Why then is the theory of bottlenecking more plausible than the theory that we descended from a single human being?

I am just trying to make sense of the little I know about evolution of human beings. Any insight into this will be appreciated. Thanks.

(PS. Iam pretty new to this forum. So I probably do not know how this forum works. I thought every new idea or new thought should be a new topic. So I thought this should be a new topic too. But from what I understood from what Percy (from Admin) said, I can post this here.)

Edited by Europa, : No reason given.


Replies to this message:
 Message 79 by Wounded King, posted 03-24-2011 8:58 AM Europa has responded
 Message 80 by Granny Magda, posted 03-24-2011 9:00 AM Europa has responded
 Message 81 by Son, posted 03-24-2011 11:39 AM Europa has responded
 Message 83 by Taq, posted 03-24-2011 12:44 PM Europa has responded
 Message 84 by PaulK, posted 03-24-2011 1:40 PM Europa has responded

    
Wounded King
Member (Idle past 1627 days)
Posts: 4149
From: Edinburgh, Scotland
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 responded

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

    
Granny Magda
Member
Posts: 2320
From: UK
Joined: 11-12-2007
Member Rating: 4.8


Message 80 of 118 (609890)
03-24-2011 9:00 AM
Reply to: Message 78 by Europa
03-24-2011 7:35 AM


Re: Becoming Human
Hi Europa,

So, instead of saying ME had companions, why don't we say we do not know whether ME had companions?

I am not saying that ME is the Bilical Eve. But, because we have someone like ME, I think it favours the theory that we are descendants of a single human being. Why then is the theory of bottlenecking more plausible than the theory that we descended from a single human being?

Well this is awkward...

You do know about the birds and the bees don't you?

Mutate and Survive


On two occasions I have been asked, "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" ... I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. - Charles Babbage
This message is a reply to:
 Message 78 by Europa, posted 03-24-2011 7:35 AM Europa has responded

Replies to this message:
 Message 85 by Europa, posted 03-26-2011 4:49 AM Granny Magda has responded

    
Son
Member (Idle past 1362 days)
Posts: 346
From: France,Paris
Joined: 03-11-2009


Message 81 of 118 (609902)
03-24-2011 11:39 AM
Reply to: Message 78 by Europa
03-24-2011 7:35 AM


Re: Becoming Human
Just to make what others said clearer. All the grandchildren of your grandmother are descended from your grandmother, right? Does that mean that all your grandchildren have only one grandmother they descended from? Does it mean all your first cousins are descended from a single human being, your grandmother?
This message is a reply to:
 Message 78 by Europa, posted 03-24-2011 7:35 AM Europa has responded

Replies to this message:
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Taq
Member
Posts: 7141
Joined: 03-06-2009
Member Rating: 3.9


Message 82 of 118 (609909)
03-24-2011 12:37 PM
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.

Completely agree. For the purposes of the calculations I was going with the best case scenario.


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Taq
Member
Posts: 7141
Joined: 03-06-2009
Member Rating: 3.9


Message 83 of 118 (609910)
03-24-2011 12:44 PM
Reply to: Message 78 by Europa
03-24-2011 7:35 AM


Re: Becoming Human
If you accept this to be true, how do you fit Mitochondrial Eve into the scenario?

How does it not fit into this scenario? For every gene there will be a most recent common ancestor (MRCA), and they will undoubtedly be different MRCA's for many genes. Our genomes are undoubtedly made up of DNA that was not found in ME but was found her contemporaries.

Let's use language as an example. There are many different words in the english language. It would be incorrect to trace the origin of a single english word and date the origin of the entire language based on the origin of that single word. And yet, this is exactly what you are doing with ME. Our mitochondrial genome is but a single piece of our entire genome. There are many different points of origin for different genes just as there are many different points of origin for different words in the english language.


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

Replies to this message:
 Message 88 by Europa, posted 03-26-2011 5:22 AM Taq has responded

  
PaulK
Member
Posts: 13125
Joined: 01-10-2003
Member Rating: 2.8


Message 84 of 118 (609915)
03-24-2011 1:40 PM
Reply to: Message 78 by Europa
03-24-2011 7:35 AM


Re: Becoming Human
quote:

At one time, we were ape-like primates. We lived in the jungle, probably on trees. We became humans. Not overnight. But gradually, over millions of years. This is the accepted scientific theory about how human beings originated. According to this theory, there was no first human being. There was no Adam, nor Eve.

It is more accurate to say that the question of the "first human" is very fuzzy and not very important. That is, if we had a hard definition of human there would almost certainly be a unique individual who was the first to meet that definition, but it is populations that evolve and we would all be descended from a number of individuals in the population (and likely a very large proportion of that population).

quote:

If you accept this to be true, how do you fit Mitochondrial Eve into the scenario?

Very easily. Mitochondrial Eve would be one of the descendants of the population which included the first human. And she would, herself be part of a larger population.

quote:

Presently, ME is explained by saying the human population faced a bottleneck sometime in the past and that is why we have ME

Not really. Bottlenecking would only need to be invoked to explain the timing (which would affect the question of whether ME was human or not). It's a statistical inevitability that there would be some sort of ME.

quote:

I am not saying that ME is the Bilical Eve. But, because we have someone like ME, I think it favours the theory that we are descendants of a single human being. Why then is the theory of bottlenecking more plausible than the theory that we descended from a single human being?

Because the bottlenecks we have evidence for aren't severe enough ! A single original pair would be a very severe bottleneck (and if you add in the Biblical Flood you get another severe one, too).


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

Replies to this message:
 Message 89 by Europa, posted 03-26-2011 5:26 AM PaulK has responded
 Message 90 by Europa, posted 03-26-2011 5:28 AM PaulK has not yet responded

    
Europa
Member (Idle past 2219 days)
Posts: 68
Joined: 06-05-2010


Message 85 of 118 (610082)
03-26-2011 4:49 AM
Reply to: Message 80 by Granny Magda
03-24-2011 9:00 AM


Re: Becoming Human
Well this is awkward...

You do know about the birds and the bees don't you?

Well this is embarassing ...

No, I do not know about the birds and the bees.


This message is a reply to:
 Message 80 by Granny Magda, posted 03-24-2011 9:00 AM Granny Magda has responded

Replies to this message:
 Message 93 by Granny Magda, posted 03-26-2011 10:30 AM Europa has responded

    
Europa
Member (Idle past 2219 days)
Posts: 68
Joined: 06-05-2010


Message 86 of 118 (610083)
03-26-2011 4:54 AM
Reply to: Message 81 by Son
03-24-2011 11:39 AM


Re: Becoming Human
All the grandchildren of your grandmother are descended from your grandmother, right? Does that mean that all your grandchildren have only one grandmother they descended from? Does it mean all your first cousins are descended from a single human being, your grandmother?

Dear Son,

You are asking me to imagine the scenario at the top of the family tree, where my grandmother has several of her siblings, cousins, etc.

I am on the other hand asking what happened at the bottm, where the first branch took place.


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Europa
Member (Idle past 2219 days)
Posts: 68
Joined: 06-05-2010


Message 87 of 118 (610084)
03-26-2011 5:14 AM
Reply to: Message 79 by Wounded King
03-24-2011 8:58 AM


Re: Becoming Human
Thanks King for the clarification and for your patience.

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.

So, ape-like primate to human being was a slow and gradual transition?
There was no single point at which we can mark the orgin of human beings?

Also ME doesn't say that we are only descended from 1 single human being.

No it does not. But suppose there was a single human being from which we all descended, will we not have an ME?

the MRCA calculations for various other genetic markers extend back well beyond ME

Are these markers also present in everyone alive today?

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 think you misinterpreted what i said. Yes I do mean we all descended from a single human being. But I also mean that ME may not necessarily be the BIBLICAL Eve.


This message is a reply to:
 Message 79 by Wounded King, posted 03-24-2011 8:58 AM Wounded King has responded

Replies to this message:
 Message 100 by Wounded King, posted 03-27-2011 7:03 AM Europa has acknowledged this reply

    
Europa
Member (Idle past 2219 days)
Posts: 68
Joined: 06-05-2010


Message 88 of 118 (610085)
03-26-2011 5:22 AM
Reply to: Message 83 by Taq
03-24-2011 12:44 PM


Re: Becoming Human
For every gene there will be a most recent common ancestor (MRCA), and they will undoubtedly be different MRCA's for many genes.

Agreed.
If all human beings alive today have a particular gene (marker) and if this can be traced back to a point where it originated, it is only obvious that we all descended from that individual. No?


This message is a reply to:
 Message 83 by Taq, posted 03-24-2011 12:44 PM Taq has responded

Replies to this message:
 Message 101 by Wounded King, posted 03-27-2011 7:18 AM Europa has acknowledged this reply
 Message 102 by Taq, posted 03-28-2011 6:59 PM Europa has acknowledged this reply

    
Europa
Member (Idle past 2219 days)
Posts: 68
Joined: 06-05-2010


Message 89 of 118 (610086)
03-26-2011 5:26 AM
Reply to: Message 84 by PaulK
03-24-2011 1:40 PM


Re: Becoming Human
Very easily. Mitochondrial Eve would be one of the descendants of the population which included the first human. And she would, herself be part of a larger population.

Why is it we don't have the evidence for any of the other members of this population?
I mean why is it that we do not have more markers that can be traced to someone who lived during ME's time?


This message is a reply to:
 Message 84 by PaulK, posted 03-24-2011 1:40 PM PaulK has responded

Replies to this message:
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 Message 92 by jar, posted 03-26-2011 10:07 AM Europa has responded

    
Europa
Member (Idle past 2219 days)
Posts: 68
Joined: 06-05-2010


Message 90 of 118 (610087)
03-26-2011 5:28 AM
Reply to: Message 84 by PaulK
03-24-2011 1:40 PM


Re: Becoming Human
A single original pair would be a very severe bottleneck

Yes. But is there any evidence to say it cannot be such a severe bottleneck?


This message is a reply to:
 Message 84 by PaulK, posted 03-24-2011 1:40 PM PaulK has not yet responded

    
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