In article <fl8qts$g1o$1@reader2.panix.com>, jdnicoll@panix.com (James
Nicoll) says...

[deletia]

> In my experience, books set after the extinction of humanity fall
> into two broad groups:
>
> We became something better, leaving the Earth for our successors.

[...]

> The other sort of apres-human setting has us shuffled offstage by
> some inherent flaw in our character or some great calamity that we were
> unable to avoid.

If anyone were still writing *science* fiction, the two scenarios would
be combined, one the necessary precursor for the other. Evolution is
pretty well understood. One of the basic laws of evolution is that the
rate of evolution is inversely proportional to the size of the breeding
population. Natural selection is not relevant until it eliminates
alleles from the gene pool. It can not do that while the alleles are
distributed throughout a large population.

In order to evolve, a species has to be dragged through a reproductive
knot hole. That happened to the human race about 200,000 years ago.
Around that time, there were only at most a few thousand of us in the
world, and perhaps just a few hundred. We became isolated from our
precursor species, and were subject to vicious natural selection
pressures. To evolve into another species, you have to flirt very
intimately with extinction.

First you need a catastrophe, where you escape total extinction by the
skin of your teeth. Then you need a really, really hard time that kills
a substantial proportion of each succeeding generation, allowing just
enough of a niche for the fittest to survive. The result, in a
surprisingly few generations, is a new species that will either survive
and thrive, or leave a very few puzzling fossils.

Your guess is as good as mine as to what the successor species to humans
will look or think like, but they aren't going to show up while billions
of people are mucking about. A dinosaur killer sized asteroid would get
evolution moving again, but for the time being, what you see is what you
are going to get.

Incidentally, evolutionary processes are the obvious resolution to the
Fermi Paradox. No biological species can persist by splitting off tiny
reproductive groups. Many interstellar colonies would quickly evolve
into something else, possibly before they even got to their
destination. One obvious survival trait on a generation ship would be a
biological imperative for population control. Without an uncontrolled
population, interstellar colonization starts to look like a huge waste
of resources.

--
For email, replace firstnamelastinitial
with my first name and last initial.

Larry Caldwell wrote:

> In article <fl8qts$g1o$1@reader2.panix.com>, jdnicoll@panix.com
> (James Nicoll) says...
>
> [deletia]
>
> > In my experience, books set after the extinction of humanity fall
> > into two broad groups:
> >
> > We became something better, leaving the Earth for our successors.
>
> > The other sort of apres-human setting has us shuffled offstage by
> > some inherent flaw in our character or some great calamity that we
> > were unable to avoid.
>
> If anyone were still writing science fiction, the two scenarios would
> be combined, one the necessary precursor for the other. Evolution is
> pretty well understood. One of the basic laws of evolution is that
> the rate of evolution is inversely proportional to the size of the
> breeding population. Natural selection is not relevant until it
> eliminates alleles from the gene pool. It can not do that while the
> alleles are distributed throughout a large population.

Maybe, but some experts have reason to doubt it. See
http://johnhawks.net/weblog/topics/evolution/selection/acceleration/accel_story_2007.html

--
Dan Goodman
"I have always depended on the kindness of stranglers."
Tennessee Williams, A Streetcar Named Expire
Journal http://dsgood.livejournal.com
Futures http://dangoodman.livejournal.com
mirror 1: http://dsgood.insanejournal.com
mirror 2: http://dsgood.wordpress.com
Links http://del.icio.us/dsgood

Larry Caldwell <firstnamelastinitial@peaksky.com> wrote:
>One of the basic laws of evolution is that the
>rate of evolution is inversely proportional to the size of the breeding
>population. Natural selection is not relevant until it eliminates
>alleles from the gene pool. It can not do that while the alleles are
>distributed throughout a large population.

....This has enough issues in it I don't know where to start. Natural selection
can go perfectly well without "eliminating" alleles, if new better-adapted
alleles - or even existing better-adapted ones - show up; what do you think
'recessive genes' _are_, anyway? And the rate of evolution is not anything
like mathematically fixed to the size of the breeding population; that would
mean _every_ species that was nearly extinct would be speciating frantically,
while none of the bacteria or viruses could evolve at all relative to
multicellular life forms.

I'm sure there's an idea or two behind this that are what you meant to be
saying, but they're not apparent from this side of the paragraph.

>In order to evolve, a species has to be dragged through a reproductive
>knot hole.

Bzzt. There is no such necessity. Go read your Darwin; even he got this
right. All that needs to happen is that some of the variants of the species
are better-adapted to their current environment than others, _in ways that
are inheritable_. Where "environment" can get pretty metaphysical, since it
includes pretty much anything that gets involved with getting the next
generation out there.

Certainly passing through a bottleneck (the usual term) CAN cause rapid
changes in a species compared to what existed before said bottleneck, but
it is by no means REQUIRED that this happen, in any way, for evolution to
occur. Thinking it is will get you some very wrong mental results.

>To evolve into another species, you have to flirt very
>intimately with extinction.

Wrong. Sorry. Go back and re-read.

Dave
--
\/David DeLaney posting from dbd@vic.com "It's not the pot that grows the flower
It's not the clock that slows the hour The definition's plain for anyone to see
Love is all it takes to make a family" - R&P. VISUALIZE HAPPYNET VRbeable<BLINK>
http://www.vic.com/~dbd/ - net.legends FAQ & Magic / I WUV you in all CAPS! --K.

In article <slrnfngs5d.ma1.dbd@gatekeeper.vic.com>,
dbd@gatekeeper.vic.com (David DeLaney) says...
> Larry Caldwell <firstnamelastinitial@peaksky.com> wrote:
> >One of the basic laws of evolution is that the
> >rate of evolution is inversely proportional to the size of the breeding
> >population. Natural selection is not relevant until it eliminates
> >alleles from the gene pool. It can not do that while the alleles are
> >distributed throughout a large population.
>
> ...This has enough issues in it I don't know where to start. Natural selection
> can go perfectly well without "eliminating" alleles, if new better-adapted
> alleles - or even existing better-adapted ones - show up; what do you think
> 'recessive genes' _are_, anyway? And the rate of evolution is not anything
> like mathematically fixed to the size of the breeding population; that would
> mean _every_ species that was nearly extinct would be speciating frantically,
> while none of the bacteria or viruses could evolve at all relative to
> multicellular life forms.

I don't think you understand what "selection" means. It means denying
reproductive success to inheritable traits. By definition, that means
eliminating alleles. Bacteria evolve rapidly when they are nearly
exterminated. Antibiotic resistance often involves selecting for traits
that would be undesirable in the absence of antibiotics. Bacteria shed
genes that they have developed over millions of years, in order to
survive the hostile environment of penicillin. Of course, this requires
that only a tiny percentage survive each exposure. And yes, they are
speciating rapidly.

Recessive genes are genes that only express when dominant genes are not
present. In many cases, the dominant and recessive genes for a trait
are not even located on the same chromosome, so an individual can carry
a full complement of both dominant and recessive genes for a trait.

Some genes are neither dominant or recessive, like the recently mutated
sickle cell gene, which offers resistance to malaria to anyone with half
a pair and kills anyone with a full pair. It's a classic Mendelian
distribution. Both mom and dad survive to reproduce because they are
XO. One kid ends up OO and dies of malaria. Two kids end up XO and
survive malaria. One kid ends up XX and dies of sickle cell anemia.
This is a classic example of a selection process that does not result in
speciation, because survival requires carrying a full set of alleles.

> >In order to evolve, a species has to be dragged through a reproductive
> >knot hole.
>
> Bzzt. There is no such necessity. Go read your Darwin; even he got this
> right. All that needs to happen is that some of the variants of the species
> are better-adapted to their current environment than others, _in ways that
> are inheritable_. Where "environment" can get pretty metaphysical, since it
> includes pretty much anything that gets involved with getting the next
> generation out there.

Darwin is a bit out of date, but he based his observations on tiny,
isolated populations. He discovered a wealth of unique species on small
islands like the Galapagos, where animals had reproduced in very small
groups, resulting in rapid speciation.

> Certainly passing through a bottleneck (the usual term) CAN cause rapid
> changes in a species compared to what existed before said bottleneck, but
> it is by no means REQUIRED that this happen, in any way, for evolution to
> occur. Thinking it is will get you some very wrong mental results.

In the presence of large and mobile breeding populations, species are
stable for millions of years. When populations are small and isolated,
they can evolve to a new species in a very brief time, on the scale of
thousands, or even hundreds, of years.

> >To evolve into another species, you have to flirt very
> >intimately with extinction.
>
> Wrong. Sorry. Go back and re-read.

There was quite a bit of discussion 30 years ago about the "Punctuated
Equilibrium" articles by Stephen Jay Gould. He pointed out that species
were stable for long stretches of time, followed by a spate of rapid
extinctions and speciation. The biologists and mathematicians solved
the conundrum by pointing out that the rate of allele loss in a large
breeding population makes a glacier look like a formula race car. If
you want to select for new traits, you have to eliminate a large
percentage of the breeding population with each generation. You simply
can't select that rigorously and maintain a large breeding population.

With a mobile breeding population in the billions, the human race is set
to be a stable species for the next 100 million years. When natural
selection gets around to eliminating 20% of the breeding population of
each generation, the human race will be back on the evolutionary fast
track. It would take several centuries, but eventually new survival
traits would become common, and the population would become small enough
to be forced to inbreed. That's the other half of the selection
process. First you select for desirable traits, then you inbreed to fix
those traits, and you have a new species.

--
For email, replace firstnamelastinitial
with my first name and last initial.

In article <477865f0$0$27494$804603d3@auth.newsreader.iphouse. com>,
dsgood@iphouse.com (Dan Goodman) says...

> Maybe, but some experts have reason to doubt it. See
> http://johnhawks.net/weblog/topics/evolution/selection/acceleration/accel_story_2007.html

Interesting. I hope his papers are more rigorous than his blog. For
instance, the mutation for lactase persistence occurred twice, once in
Scandinavia and once in East Africa. It's also not that much of a
mutation, since populations that do not carry either mutation still show
a percentage of lactase persistence.

He also avoids discussing the precipitous drop in human genetic
variability since the last ice age, even though it is clearly visible on
his graphs.

--
For email, replace firstnamelastinitial
with my first name and last initial.

On Sun, 30 Dec 2007 18:38:12 -0800, Larry Caldwell
<firstnamelastinitial@peaksky.com> wrote:

>In order to evolve, a species has to be dragged through a reproductive
>knot hole. That happened to the human race about 200,000 years ago.
>Around that time, there were only at most a few thousand of us in the
>world, and perhaps just a few hundred. We became isolated from our
>precursor species, and were subject to vicious natural selection
>pressures. To evolve into another species, you have to flirt very
>intimately with extinction.

That's how natural selection usually works. I'm not sure it always
works that way. For instance the development of extreme antlers
might have just been so attractive to females that small antlered just
didn't reproduce.

And of course, we now are getting close to being able to artificially
select our genes.

On Mon, 31 Dec 2007 14:42:54 -0500, dbd@gatekeeper.vic.com (David
DeLaney) wrote:

>>And of course, we now are getting close to being able to artificially
>>select our genes.
>
>A-yep. Which, curiously, doesn't take us "out of the concept of evolution" -
>all it does is make more variation possible, by means not usually available
>to species. The selections that turn out to enhance their own ability to be
>passed on will outdo the ones that don't...

But it certainly could be quicker.

Larry Caldwell <firstnamelastinitial@peaksky.com> wrote:
>dbd@gatekeeper.vic.com (David DeLaney) says...
>> Larry Caldwell <firstnamelastinitial@peaksky.com> wrote:
>> >One of the basic laws of evolution is that the
>> >rate of evolution is inversely proportional to the size of the breeding
>> >population. Natural selection is not relevant until it eliminates
>> >alleles from the gene pool. It can not do that while the alleles are
>> >distributed throughout a large population.
>>
>> ...This has enough issues in it I don't know where to start. Natural selection
>> can go perfectly well without "eliminating" alleles, if new better-adapted
>> alleles - or even existing better-adapted ones - show up; what do you think
>> 'recessive genes' _are_, anyway? And the rate of evolution is not anything
>> like mathematically fixed to the size of the breeding population; that would
>> mean _every_ species that was nearly extinct would be speciating frantically,
>> while none of the bacteria or viruses could evolve at all relative to
>> multicellular life forms.
>
>I don't think you understand what "selection" means.

From that statement, I _know_ that you don't understand what the 'selection'
in 'natural selection' means.

>It means denying
>reproductive success to inheritable traits.

Nope. It means "selecting for traits that are more adapted to the current
environment". No part of it necessitates an absolute denial of reproductive
success for ANY organism involved; all that's necessary is that some of them
are MORE successful than others.

Since you're arguing from false premises, and appear to have built an entire
mental structure on them, I am quite unlikely to be able to get through to
you that you're far enough from standard evolutionary theory that you can't
see most of the details from where you are... so have a nice time where you're
standing.

Dave
--
\/David DeLaney posting from dbd@vic.com "It's not the pot that grows the flower
It's not the clock that slows the hour The definition's plain for anyone to see
Love is all it takes to make a family" - R&P. VISUALIZE HAPPYNET VRbeable<BLINK>
http://www.vic.com/~dbd/ - net.legends FAQ & Magic / I WUV you in all CAPS! --K.

On Mon, 31 Dec 2007 11:31:03 -0700, Howard Brazee <howard@brazee.net> wrote:
>Larry Caldwell <firstnamelastinitial@peaksky.com> wrote:
>>In order to evolve, a species has to be dragged through a reproductive
>>knot hole. That happened to the human race about 200,000 years ago.
>>Around that time, there were only at most a few thousand of us in the
>>world, and perhaps just a few hundred. We became isolated from our
>>precursor species, and were subject to vicious natural selection
>>pressures. To evolve into another species, you have to flirt very
>>intimately with extinction.
>
>That's how natural selection usually works.

That's not even how it 'usually' works. It's how it -sometimes- works; most
of the time it works through small differential advantages from variations in
a given species.

>And of course, we now are getting close to being able to artificially
>select our genes.

A-yep. Which, curiously, doesn't take us "out of the concept of evolution" -
all it does is make more variation possible, by means not usually available
to species. The selections that turn out to enhance their own ability to be
passed on will outdo the ones that don't...

Dave
--
\/David DeLaney posting from dbd@vic.com "It's not the pot that grows the flower
It's not the clock that slows the hour The definition's plain for anyone to see
Love is all it takes to make a family" - R&P. VISUALIZE HAPPYNET VRbeable<BLINK>
http://www.vic.com/~dbd/ - net.legends FAQ & Magic / I WUV you in all CAPS! --K.

Howard Brazee <howard@brazee.net> wrote:
>dbd@gatekeeper.vic.com (David DeLaney) wrote:
>
>>>And of course, we now are getting close to being able to artificially
>>>select our genes.
>>
>>A-yep. Which, curiously, doesn't take us "out of the concept of evolution" -
>>all it does is make more variation possible, by means not usually available
>>to species. The selections that turn out to enhance their own ability to be
>>passed on will outdo the ones that don't...
>
>But it certainly could be quicker.

Depends. Bacteria can do something like 100 generations a day, if I recall
correctly... and whatever we end up doing will CERTAINLY have middle management
involved SOMEWHERE.

Dave
--
\/David DeLaney posting from dbd@vic.com "It's not the pot that grows the flower
It's not the clock that slows the hour The definition's plain for anyone to see
Love is all it takes to make a family" - R&P. VISUALIZE HAPPYNET VRbeable<BLINK>
http://www.vic.com/~dbd/ - net.legends FAQ & Magic / I WUV you in all CAPS! --K.

["Followup-To:" header set to rec.arts.sf.science.]
On 2007-12-31, Larry Caldwell <firstnamelastinitial@peaksky.com> wrote:
> In article <slrnfngs5d.ma1.dbd@gatekeeper.vic.com>,
> dbd@gatekeeper.vic.com (David DeLaney) says...
>> Larry Caldwell <firstnamelastinitial@peaksky.com> wrote:
>> >One of the basic laws of evolution is that the
>> >rate of evolution is inversely proportional to the size of the breeding
>> >population. Natural selection is not relevant until it eliminates
>> >alleles from the gene pool. It can not do that while the alleles are
>> >distributed throughout a large population.
>>
>> ...This has enough issues in it I don't know where to start. Natural selection
>> can go perfectly well without "eliminating" alleles, if new better-adapted
>> alleles - or even existing better-adapted ones - show up; what do you think
>> 'recessive genes' _are_, anyway? And the rate of evolution is not anything
>> like mathematically fixed to the size of the breeding population; that would
>> mean _every_ species that was nearly extinct would be speciating frantically,
>> while none of the bacteria or viruses could evolve at all relative to
>> multicellular life forms.
>
> I don't think you understand what "selection" means. It means denying
> reproductive success to inheritable traits.

No, it means differential reproductive success. One allele variant just
has to be less successful than another, not be eliminated.

>> >In order to evolve, a species has to be dragged through a reproductive
>> >knot hole.
>>
>> Bzzt. There is no such necessity. Go read your Darwin; even he got this
>> right. All that needs to happen is that some of the variants of the species
>> are better-adapted to their current environment than others, _in ways that
>> are inheritable_. Where "environment" can get pretty metaphysical, since it
>> includes pretty much anything that gets involved with getting the next
>> generation out there.
>
> Darwin is a bit out of date, but he based his observations on tiny,
> isolated populations. He discovered a wealth of unique species on small
> islands like the Galapagos, where animals had reproduced in very small
> groups, resulting in rapid speciation.
>
>> Certainly passing through a bottleneck (the usual term) CAN cause rapid
>> changes in a species compared to what existed before said bottleneck, but
>> it is by no means REQUIRED that this happen, in any way, for evolution to
>> occur. Thinking it is will get you some very wrong mental results.
>
> In the presence of large and mobile breeding populations, species are
> stable for millions of years. When populations are small and isolated,
> they can evolve to a new species in a very brief time, on the scale of
> thousands, or even hundreds, of years.

Evolution is _much_ broader than speciation.

--
Aaron Denney
-><-

On Fri, 4 Jan 2008 01:57:11 +0000 (UTC), Aaron Denney <wnoise@ofb.net>
wrote:

>["Followup-To:" header set to rec.arts.sf.science.]
>On 2007-12-31, Larry Caldwell <firstnamelastinitial@peaksky.com> wrote:
>> In article <slrnfngs5d.ma1.dbd@gatekeeper.vic.com>,
>> dbd@gatekeeper.vic.com (David DeLaney) says...
>>> Larry Caldwell <firstnamelastinitial@peaksky.com> wrote:
>>> >One of the basic laws of evolution is that the
>>> >rate of evolution is inversely proportional to the size of the breeding
>>> >population. Natural selection is not relevant until it eliminates
>>> >alleles from the gene pool. It can not do that while the alleles are
>>> >distributed throughout a large population.
>>>
>>> ...This has enough issues in it I don't know where to start. Natural selection
>>> can go perfectly well without "eliminating" alleles, if new better-adapted
>>> alleles - or even existing better-adapted ones - show up; what do you think
>>> 'recessive genes' _are_, anyway? And the rate of evolution is not anything
>>> like mathematically fixed to the size of the breeding population; that would
>>> mean _every_ species that was nearly extinct would be speciating frantically,
>>> while none of the bacteria or viruses could evolve at all relative to
>>> multicellular life forms.
>>
>> I don't think you understand what "selection" means. It means denying
>> reproductive success to inheritable traits.
>
>No, it means differential reproductive success. One allele variant just
>has to be less successful than another, not be eliminated.
>
And, just to be clear, the "best adapted" creature is not necessarily
the one chosen for, if a slightly-less adapted creature has more
surviving offspring. For example, a creature that is perfectly
adapted to the environment and has two surviving offspring is going to
be out-competed by a creature that is slightly less well adapted, but
has 6 surviving offspring. (Assuming, of course, that the offspring
show the same characteristics as their parents.)

Rebecca