On 20-7-2009 0:46, clipka wrote:
> andrel <a_l### [at] hotmailcom> wrote:
>> * if we have 30000 genes and we have 98% of our genes in common with the
>> two species of chimp than there are at least 300 ancestors common to all
>> humans since our split of the chimp line, and probably much more.
> 
> According to http://www.genetics.org/cgi/content/full/156/1/297, it's 199
> differences.

That is 199 in the area they searched, which was only about 11000 
basepairs. The total amount they still estimate at 1.2% (and 
http://www.gate.net/~rwms/EvoEvidence.html at 1.6 and 1.7%) which means 
that the actual number of differences between you and that chimp in the 
zoo is more in the 100 million ballpark.

> Furthermore, there are two basic fallacies in this argumentation:
> 
> * Given that the average number of mutations *per individual* is estimated at
> about ~175 (!) in each generation (see aforementioned article - man, I confess
> this sounds crazy!), all these 199 differences might have been acquired in just
> one or two generations.
> 
> * It is not even necessary for all of these mutations to have occurred *after*
> the split of the chimp/human line. Some may have been genetic differences that
> were introduced earlier in the common ancestors of chimps and humans, but with
> each variant prevailing in only one branch.

That is true. That is even true for the number that I was looking for: 
the number of mutations that are present in all humans and not in either 
chimp species. My initial estimate (above) is clearly nonsense, I admit, 
but perhaps someone has a better idea.

> For instance, such a gene may have affected some aspect of visual appearance
> which our common ancestors did not care much about, but which may have had a
> beneficial side-effect for the new 46-chromosome group, therefore becoming more
> and more frequent among it as the groups evolved apart; another mutation may
> then have spread in the 48-chromosome group to consider this visual feature
> unpleasant, further reducing the interbreeding rate and at the same time
> beginning to extinguishing that feature in the 48-chromosome group.
> 
> 
> So all we can really say about it all is that there is at least *one* common
> ancestor to all humankind with any relation to the chimp/human separation: The
> individual to be the first with 47 instead of 48 chromosomes.

I would vote for the inversions too, although they can have occurred 
simultaneously. Yet, I think that is not likely.

There is also that thing that if we would biotechnically separate 
chromosome 2 again along the original lines, would the resulting 
offspring be a person or an animal, human or chimp?

Ethically not permissible of course, but I find the idea of generating a 
line of links between us and our chimp brothers quite appealing. If only 
to annoy the pope and the born again Christians. Though perhaps the 
possibility of creating intermediate chimans (humps?) would be enough to 
have them think again.

Reality check: would my ethics change if there was an intermediate 
(sub)species between humans an chimps? Checking... a bit, but no major 
rebuilding necessary.
How about yours (to the group at large, or should that be a separate 
thread?)?

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