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Author Topic:   How will creationists react to the first human-chimp hybrid?
NosyNed
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Posts: 9003
From: Canada
Joined: 04-04-2003


Message 79 of 138 (449838)
01-19-2008 11:28 AM
Reply to: Message 78 by Quetzal
01-19-2008 9:02 AM


A question for Quetzal re Y and mtDNA lineages
It means that all of her other female contemporaries either were also the ancestors of all modern humans (because the carried the same mutations) or left no current descendants.
Doesn't it mean that she left "no currant descendants" through an unbroken mother to daughter line? She may well have descendants alive but there may have been a generation of all males between her and us. Correto?
I was explaining the mtDNA Eve and Y Adam to friends awhile ago and this question came to mind:
Is there an initial population size where, over enough time, you MUST get down to a single Y ancestor and singe mtDNA ancestor showing in the resultant population? In other words, is this result just what you would expect if the human (for example) population stays not "too" large for long enough?
I see this happening by pure chance as once a line happens to encounter an all male (for the mtDNA) generation it is gone and over time we would expect the number of threads of mtDNA to dwindle.
Has there been any pop. gen work on this?

This message is a reply to:
 Message 78 by Quetzal, posted 01-19-2008 9:02 AM Quetzal has replied

Replies to this message:
 Message 80 by Quetzal, posted 01-19-2008 12:31 PM NosyNed has replied

  
NosyNed
Member
Posts: 9003
From: Canada
Joined: 04-04-2003


Message 81 of 138 (449860)
01-19-2008 1:42 PM
Reply to: Message 80 by Quetzal
01-19-2008 12:31 PM


Re: A question for Quetzal re Y and mtDNA lineages
"Eve" is the one that did leave descendants.
Pronoun antecedent problems here. My "she" was the one who left her mtDNA in no descendents.
A point of clarification might be good here:
While "Eve: maybe the only one whose mtDNA got through that does NOT mean that many other women don't have descendants alive today. In fact, I may be related to half (or more ) of ALL humans alive 100,000 years ago. Nao?
Not really. I'm not expert at this (pop gen was my second worst course in school, and I have attemptd faithfully to avoid it since), but my understanding is that initial population size doesn't matter - eventually every lineage will coalesce. Remember, we're tracing polymorphisms back in time from current populations. Additionally, it doesn't matter much what the size of the sample of modern populations is - the statistical variance based on sample size, which is usually 1/n, is only 1/logn with coalescent theory (don't ask me why). So either way you look at it, population size doesn't matter.
The "tracing back from current" leaves me with a bit of room for confusion.
Are you saying "initial" == current population size doesn't matter? That makes sense to me.
When I said "initial" I meant the population at sometime in the past. Specifically the time of mtDNA Eve or Y Adam. Does that also not matter? It seems to me that it must matter. At least if it was larger then I must have more time before the lineages coalesce. Obviously a population of 20 million during Roman times will not have coalesced under most circumstances by now. But a population of 1,000 may well be almost sure to have.
BTW: I'm about half way through "Adam's Curse" by Bryan Sykes. It is an excellent read (that is easy) and full of interesting tidbits.
Thanks for the site. I'll have a peek to avoid any more silly questions.

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NosyNed
Member
Posts: 9003
From: Canada
Joined: 04-04-2003


Message 122 of 138 (500132)
02-23-2009 11:02 AM
Reply to: Message 121 by SpicyCurry
02-23-2009 8:49 AM


An aside
Simply put, DNA is quite literally like a blueprint for a house.
This is NOT the place to discuss this at length. But the blueprint analogy is one I took for granted for years until someone here, somewhere pointed out that it is utterly wrong.
DNA is not literally like anything but it is most analogous to a recipe.
A recipe doesn't say to put the bathroom anywhere and it doesn't have little pictures of what to build (though cookbooks put some in for some recipes to help sell the books). It simple says, add this, add that, stir, bake etc. The outcome is not obviously predictable from the recipe (and in my case not what actually comes out sometimes).

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NosyNed
Member
Posts: 9003
From: Canada
Joined: 04-04-2003


Message 126 of 138 (501702)
03-07-2009 2:09 PM
Reply to: Message 125 by ausar_maat
03-07-2009 12:40 PM


Labelling Chromosomes
But now, here's one problem I have, since this thread is about humans and chimps. I'm trying to understand how is it that according to Hiller (2005), the "extra" centromere found in chromosome 2 is related to chromosome 13 in the chimp. Shouldn't that centromere be the one from either chimp chrom 2a or 2b, since they constitutionally form chromosome 2 in man? How did chrom 13 in chimps get in this equation?
I'm not sure I actually remember reading about this but I'm semi, kinda, sorta sure that this is just an historical accident.
The two sets of chromosomes were labeled separately before there was any way to compare them in detail. At the time who cared which one you labeled 1 and a human and 1 in a chimp, no one.

This message is a reply to:
 Message 125 by ausar_maat, posted 03-07-2009 12:40 PM ausar_maat has replied

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 Message 127 by ausar_maat, posted 03-07-2009 3:11 PM NosyNed has replied

  
NosyNed
Member
Posts: 9003
From: Canada
Joined: 04-04-2003


Message 131 of 138 (501782)
03-07-2009 5:31 PM
Reply to: Message 127 by ausar_maat
03-07-2009 3:11 PM


Centromeres
I'm with the others. I don't understand what you confusion is about?????????
If chimp chromosome 13 (aka chimp 2a) (with 1 centromere) and chimp chromosome 14 (aka chimp 2b) (also with 1 centromere) join we'd expect a human chromosome with two centromeres. We would not expect a third.
Explain why you think there would be another one please?

This message is a reply to:
 Message 127 by ausar_maat, posted 03-07-2009 3:11 PM ausar_maat has replied

Replies to this message:
 Message 132 by ausar_maat, posted 03-07-2009 7:12 PM NosyNed has replied

  
NosyNed
Member
Posts: 9003
From: Canada
Joined: 04-04-2003


Message 133 of 138 (501793)
03-07-2009 7:19 PM
Reply to: Message 132 by ausar_maat
03-07-2009 7:12 PM


Re: Centromeres
Hillier made the propostion that there should be 3 centromeres?
Could you explain his reasoning? It doesn't make sense to me.

This message is a reply to:
 Message 132 by ausar_maat, posted 03-07-2009 7:12 PM ausar_maat has not replied

  
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