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On 21-7-2009 18:15, clipka wrote:
> Darren New <dne### [at] san rrcom> wrote:
>> Or it's less hard to combine 48 with 46 than you might think. All the data
>> is there, including the tollermerines (or however you spell it) in the middle.
>
> Just happened to stumble across the Wikipedia articles on mules and hinnys
> (citing the latter here):
>
> "A donkey has 62 chromosomes, whereas a horse has 64. Hinnies, being hybrids of
> those two species, have 63 chromosomes and are sterile."
>
> But later on the article reveals that this is an oversimplification:
>
> "Female mules have been known to produce offspring when mated to a purebred
> horse or donkey, though this is extremely uncommon."
>
>
> Duh. Didn't know that horses and donkeys have different numbers of chromosomes,
> too (then again, it was news to me as well that chimps and humans have).
>
> So this makes me think that...
>
> - mutations changing the number of chromosomes don't seem to be as uncommon as I
> had thought
http://en.wikipedia.org/wiki/List_of_number_of_chromosomes_of_various_organisms
is hard to explain otherwise.
> - with mules and hinnys being perfectly viable and typically not showing any
> other defects, and even *not always* being sterile, this gives rise to the
> assumption that having an odd number of chromosomes is an absolutely
> non-dramatic mutation as such (why should *only* the reproductive system show
> issues? and why not always?), and that the sterility is instead imposed by
> other genetic mechanisms "designed" (by evolution) to separate the two gene
> pools.
I guess how dramatic it is, is variable. For those that we know of it is
not an extreme problem. Where 'know of' is the important bit. If the
translocation that resulted in our chromosome 2 would not have been
viable or have been sterile, we would not have known.
You know of trisomy 21 because it is common, viable, and recognizable.
According to wikipedia trisomy 16 is actual the most common, guess why
you have never heard of it.
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andrel <a_l### [at] hotmailcom> wrote:
> > - mutations changing the number of chromosomes don't seem to be as uncommon as I
> > had thought
>
> http://en.wikipedia.org/wiki/List_of_number_of_chromosomes_of_various_organisms
> is hard to explain otherwise.
The Raccoon Dog seems particularly interesting in that respect; anyone knows
whether the subspecies can interbreed?
Hedgehogs (African vs. Woodland) likewise.
Swamp Wallabys and Echidnas have interesting chromosome configurations, too.
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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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On 22-7-2009 23:09, clipka wrote:
> andrel <a_l### [at] hotmailcom> wrote:
>>> - mutations changing the number of chromosomes don't seem to be as uncommon as I
>>> had thought
>> http://en.wikipedia.org/wiki/List_of_number_of_chromosomes_of_various_organisms
>> is hard to explain otherwise.
>
> The Raccoon Dog seems particularly interesting in that respect; anyone knows
> whether the subspecies can interbreed?
>
> Hedgehogs (African vs. Woodland) likewise.
>
> Swamp Wallabys and Echidnas have interesting chromosome configurations, too.
Genetics and male/female seems to be much much more complicated (and
interesting) than what they tough us as school.
Another think I did not know: Broccoli, cabbage, kale, kohlrabi,
brussels sprouts, and cauliflower are all the same species
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andrel wrote:
> Reality check: would my ethics change if there was an intermediate
> (sub)species between humans an chimps?
You mean like Neanderthal? Otherwise, you're going to have to define
"subspecies". :-)
--
Darren New, San Diego CA, USA (PST)
"We'd like you to back-port all the changes in 2.0
back to version 1.0."
"We've done that already. We call it 2.0."
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On 22-7-2009 23:43, Darren New wrote:
> andrel wrote:
>> Reality check: would my ethics change if there was an intermediate
>> (sub)species between humans an chimps?
>
> You mean like Neanderthal? Otherwise, you're going to have to define
> "subspecies". :-)
>
That was meant in the context of reversing some of the mutations that
separate us from the chimps (or retrofitting our mutations in them*). At
some point the 'result' will probably still be able to interbreed with
humans but be a clear subspecies with different characteristics. Halfway
down the process I expect that there will be a true species that can not
interbreed with us, bonobos, or chimps. Unlikely, but possibly, it would
be able to mate with all, which would, I think, technically mean we
would all become subspecies of this human/chimp complex. So that is why
I put '(sub)' in parentheses, because I don't know. I wasn't referring
to Neanderthal or forensis or any other humanoid that has existed.
* you can do experiments on chimps. I think such a breeding experiment
would not even be illegal, contrary to the route starting with a human.
Though somewhere along the line you would hit a legal wall, when the
chimp becomes too human. Can we predict in advance when that will be? If
not, can we afterwards decide that we did cross the line?
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andrel wrote:
> On 22-7-2009 23:43, Darren New wrote:
>> andrel wrote:
>>> Reality check: would my ethics change if there was an intermediate
>>> (sub)species between humans an chimps?
>>
>> You mean like Neanderthal? Otherwise, you're going to have to define
>> "subspecies". :-)
>>
> That was meant in the context of reversing some of the mutations that
> separate us from the chimps (or retrofitting our mutations in them*).
I understand that. Aren't neanderthals between us and the common ancestor of
us and chimps? I.e., didn't cro magnon descend from neanderthal? I guess I
should look that up myself, but...
--
Darren New, San Diego CA, USA (PST)
"We'd like you to back-port all the changes in 2.0
back to version 1.0."
"We've done that already. We call it 2.0."
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Darren New wrote:
> John VanSickle wrote:
>> Darren New wrote:
>>> Well, so much for the old "we've never seen it happen, so it can't."
>>>
>>>
http://www.geneticarchaeology.com/research/Study_catches_2_bird_populations_as_they_split_into_separate_species.asp
>>
>>
>>
>> We haven't seen it happen yet.
>
> Actually we have, dozens of times. This is just an example of "on the
> cusp." But that's OK. :-)
I notice how much of the reasoning here treats things that makes sense
and don't contradict the evidence as if they had actually been observed,
when in fact they have not. For instance, this idea of this being a
cusp. Even if it were, it could not be truly counted as observed until
it has actually passed, in which case we would no longer be "on the cusp."
Regards,
John
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John VanSickle wrote:
> Even if it were, it could not be truly counted as observed until
> it has actually passed, in which case we would no longer be "on the cusp."
Speciation has been observed happening in the wild as well as induced by
people. Based on the induced speciation, people know at least one mechanism
by which it comes about. These birds are subject to one of those mechanisms
right now, according to the researchers.
Of course, maybe it won't happen. But if you're in the final innings of a
World Series baseball game and you're ahead by several runs, it's fair to
say you're "on the cusp" of winning, even if it turns out you lose.
I.e., it's assumed they're "on the cusp", yes, but that's always true when
you use that phrase, since it's predicting the future.
Given that, the article doesn't say "on the cusp".
--
Darren New, San Diego CA, USA (PST)
"We'd like you to back-port all the changes in 2.0
back to version 1.0."
"We've done that already. We call it 2.0."
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On 23-7-2009 1:11, Darren New wrote:
> andrel wrote:
>> On 22-7-2009 23:43, Darren New wrote:
>>> andrel wrote:
>>>> Reality check: would my ethics change if there was an intermediate
>>>> (sub)species between humans an chimps?
>>>
>>> You mean like Neanderthal? Otherwise, you're going to have to define
>>> "subspecies". :-)
>>>
>> That was meant in the context of reversing some of the mutations that
>> separate us from the chimps (or retrofitting our mutations in them*).
>
> I understand that. Aren't neanderthals between us and the common
> ancestor of us and chimps? I.e., didn't cro magnon descend from
> neanderthal? I guess I should look that up myself, but...
>
There is no easy way to know which mutations occured later, so a
complete rollback is impossible. Besides I suggested to start with the
biggest changes (some of them presumably among the oldest) first, so
that the result of that operation would not result in a species that had
ever existed. If cro magnon or neaderthal were a dead end, you can not
reach them even if you knew exactly in what order the mutations arose
starting from our common ancestor until modern humans.
But you knew that.
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