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On Tue, 11 Jan 2011 14:43:59 -0800, Darren New wrote:
> Warp wrote:
>> Of course it is. It's an implicit encouragement from the government
>> for
>> people to follow a religious custom.
>
> Does this mean Black History Month implies you should go out and be
> Black for a few weeks?
>
> (Sorry. Just being silly.)
Silliness is a good thing. :-)
Maybe if more people went out and stood in the shoes of minorities,
though, they'd have a better appreciation for what being a minority in
the US is really like.
Jim
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Warp wrote:
> When the president speaks to the country on a televised official ceremony,
> that's quite different from the president talking with a friend.
Apparently, the Congress requires the President to announce the national day
of prayer. Obama is the most atheist-friendly president we've ever had, afaik.
"""
The Congress, by Public Law 100-307, as amended, has called on the President
to issue each year a proclamation designating the first Thursday in May as a
"National Day of Prayer."
"""
--
Darren New, San Diego CA, USA (PST)
Serving Suggestion:
"Don't serve this any more. It's awful."
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On 12/01/2011 9:06 AM, Warp wrote:
>
> AFAIK snakes have vestigial limbs (usually quite obvious when looking
> at their skeletons).
>
Yes. I said as much. Vestigial.
Snakes are tetrapods and yet you cannot find 5 digits on the end of a
limb in the vast majority of individuals. Some individuals may have
more evidence than the average. Rarely a quite recognisable but non
functional leg. All may have some relic or indication of where limbs
existed in ancestral forms.
The original assertion that 'fingers' always number 5 in tetrapods is
not totally correct.
There is a strong connection between limb development and the overall
foetal development path. And genital development is a big part of that
as well. The 'Homeobox' or 'Hox' genes are what Darren had read about
and the gist of what he said is true enough. All tetrapods (as far as
is known) have 5 'buds' or zones per limb during development that are
eligible to become fingers / toes.
But there are variations in the Hox genes that alter limb development
and are not fatal. There can be other genes involved that modify the
basic structures and even cause them to disappear as the foetus develops.
As shown by polydactylism in humans and cats there can be more than 5
fully formed functional digits on each limb. From what I've read, the
mechanism leading to this is duplication of one of the existing digits
rather than a completely new type of digit. Having an exact copy of a
digit alongside the original doesn't seem to have enough advantage to
overcome the associated risks to the rest of the development process.
Evolutionary development can proceed from a duplicate gene. So long as
it isn't fatal the possibility exists that some other mutation or gene
variant will modify the duplicate some time in the future to be actually
useful.
As a conjecture, there is probably selection for mechanisms that provide
genetic flexibility. A species that has a certain degree of variablity
is more likely to have individuals within it that can survive some
change in the environment than one that doesn't. So evolving the
ability to have mutations and carry variations has its own advantage.
On the flip side, really optimising for a niche may come at the cost of
that variability. Evolution of the mechanism of evolution!
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Le 11/01/2011 23:35, Darren New a écrit :
> Warp wrote:
>> Darren New <dne### [at] san rrcom> wrote:
>>> Warp wrote:
>>>> life on Earth wouldn't exist because
>>>> all bodies of water would freeze from the bottom up, killing all living
>>>> organisms.
I would ponder to "all massive living organisms".
Bacteria & such would be still be fine.
Can a cloud/colony of bacteria develops as an intelligent
being/population and make something fancy ?
>>
>>> Well, unless they evolved in San Diego. ;-)
>>
>> The reference is completely lost on me.
>
> Water outside doesn't freeze in San Diego. It rarely goes below freezing
> here, let alone long enough to make water freeze solid outdoors.
>
If you compress it hard enough, even in San Diego, even oxygen could
freeze...
Water is paradoxal in that at high pressure the more compact form is
liquid rather than solid.
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>> but maybe that's just because we haven't figured out yet what is
>> driving those events, so they just *appear* random to us.
>
> FWIW, the answer to this speculation is "no, we have proven that's not
> the case." :-)
Really? How?
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On 12/01/2011 07:08 AM, Le_Forgeron wrote:
> Water is paradoxal in that at high pressure the more compact form is
> liquid rather than solid.
Water is unusual in having half a dozen distinct phases rather than just
3...
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>> I'm not sure that's as much of a problem as you think it is for anything
>> other than fish.
>
> Well, life on Earth was completely in water for the first... what?
> 3 billion years?
Wikipedia (which is always right) asserts that "life" began 3.8 billion
years ago, and land plants appeared 475 million years ago.
3,800 - 475 = 3,325 million years = 3.3 billion years with no life on land.
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>> ID is not testable. It's so vague that any time someone falsifies it,
>> the proponents can just claim that the theory says something slightly
>> different, and hence is not falsified.
>
> That's a different problem. Denying the evidence of the failed tests
> doesn't mean that it passed the tests. It only means the proponents are
> pushing the concept regardless of whether it has failed the tests.
No, I'm saying that the ID people keep changing their minds about which
theory is the one they're advocating.
You don't change the theory half way through the experiment. That's not
how science works. If your theory is so inadequately specified that you
can change your mind about it every second Thursday, you're doing it wrong.
(But yes, the ID people *also* deny the evidence too...)
> ID is certainly testable: We've found no irreducibly complex
> substructures, we have overwhelming evidence of evolution, etc.
Correction: "Irreducibly complex" merely means that removing a single
component makes the thing stop working. We've found *plenty* of things
that are irreducibly complex. The point is, the ID people argue that
"irreducibly complex" = "cannot evolve", which is false.
All of which is window dressing, really. All of the "evidence for ID" is
actually "evidence against evolution". That's not how science works.
Einstein didn't overturn Netwon's highly successful theory of motion by
saying "hey, I think this is wrong". He did it by offering something
better. ID rests on the sadly mistaken belief that "evolution is wrong"
is the same thing as "ID is right". That's not how it works.
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> This in fact happens. We can even, in many cases, parse out what those
> *where*, sometimes by finding those extra structures still intact in
> other species.
More to the point, biological structures can *change purpose* too.
> And you are dead wrong on the later, evolution **keeps**
> masses of junk, whether it produces a benefit or not.
That too. The human genome has half a dozen broken copies of the globin
gene, for example. (Plus 4 (?) similar but not identical copies that
actually work.)
> The single cell do not, in general, contain mitochondria.
False.
Note carefully that "single-celled organisms" covers a vast variety of
life forms, only some of which are closely related. Many of these
contain mitochondria, and many do not. The fact that they are
unicellular does not correlate particularly well with the presence of
absence of mitochondria.
The distinction you're looking for is between eukaryotes and non-eukaryotes.
> Their genetics are often **far** more streamlined, because
> they can't afford to carry junk around, which doesn't do anything, for
> the reason you describe. It costs resources. Having a sort of "power
> plant" in the cell, whose genetics are 100% geared at producing excess
> amounts of energy, over what is absolutely needed by themselves, allows
> the rest of the genome, in the main cell, to be very sloppy in its
> operations, copying, cleanup, etc. Anything with such an internal power
> plant can afford to keep lots of stuff that does nothing at all, and
> only gets rid of things that are actively defective, usually not by
> deletion, but just by shutting them off, so they do nothing. This allows
> for what, in a single cell, would be egregious errors, such as making an
> exact copy of a sequence, then later having that sequence get mangled
> into a unique function. Its way harder to manage that if you can't
> afford extra copies lying around, where your energy input is drastically
> damaged, if you allow such a copy to happen.
I'm not sure I actually agree with this assessment.
> Most of
> their "changes" are, as a result, point mutation/deletion/addition, not
> the copy of whole sequences.
You got a citation for that?
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On 11/01/2011 07:56 PM, Patrick Elliott wrote:
> Seen at least one statement to the effect that "tree" isn't an accurate
> description at all, but rather the complex braiding you see at a river
> delta. It might split off in totally different directions at some
> points, but a lot of stuff close together is prone to flow back and
> forth between channels, maybe even "drifting" back together, when
> previously separate (though, so far we don't see any obvious examples of
> that).
The tree metaphor doesn't account for "horizontal gene transfer".
Bacteria reproduce asexually. However, they sometimes two cells will
hook up and swap genes with each other (without producing offspring).
Viruses, plasmids and other "transposable elements" can move genes from
cell to cell. (This is how genetic engineering works.)
The human genome actually contains several (mostly broken) viral genomes
within it. Usually a virus infects a cell, gets copied, and the cell
dies. At some point, an egg or sperm cell was infected, and the
infection became permanent. (And, presumably, not too detrimental.)
There's even some suggestion that these virii's ability to evade the
immune system might be how viviparous animals were able to evolve.
(I.e., how an embryo evades the mother's immune system.)
Then of course, the dynamic, ever-changing face of geology and geography
is such that there is an almost never-ending stream of habitats
appearing and disappearing all the time. Lakes dry out and become
multiple lakes, only to later reflood and become a single lake again.
Hydrothermal sea vents spring up, develop their own local tribe of
organisms, and then shut down, while new nearby vents appear.
Heck, black people and white people marrying, anyone?
It must surely happen all the time. It doesn't even require physical
separation. Just any time one group happens to not interact with another
group, and then later starts interacting again.
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