Re: Iain doesn't understand "Complexity" and presumes a discredited Malthusian premise.
- From: anon1@xxxxxxx
- Date: Sat, 11 Feb 2006 20:02:50 -0800
The problem is not with mere "complexity," but with "specified complexity."
There's no such thing as specified complexity in nature. There's nobody
who specifies at the start of an evolutionary sequence that
such-and-such species *must* evolve in a particular way, such as by
developing feathered wings, or by developing black and white vertical
stripes. Given a particular environmental stress, the species can adapt
to it in any of many different ways, any one of them equally good at
allowing that one species to occupy that particular niche.
There's not even such a thing as a specified niche in nature. There's
nobody who specifies at the start of an evolutionary sequence that
such-and-such species *must* evolve so as to adapt to a particular
specified set of environmental parameters. When some local environment
changes enough that species previously living there can no longer
survive, nothing requires those particular species to evolve so as to
be able to contiue surviving there. In most cases in fact such a change
drives all former residents locally extinct, and some other species
moves in to fill the void.
There's not even such a thing as a specified niche in the more general
sense of requiring some species, any species, it doesn't matter what
species, to colonize a particular new environmental niche. If the local
environment changes in such a way that former residents can no longer
live there, and no other nearby species can live there either, the
niche may go unoccupied for an indefinite time, until by chance some
species from far away happens to venture nearby and discover the niche,
or by chance some species evolves to finally survive in the niche.
Looking from the other direction, there's no thing as guaranteed
survival of any particular species. If the niche occupied by one
species changes so the species can no longer live there, it may simply
move elsewhere and live there instead. If there is no place nearby it
can live at all, it goes locally extinct. If this happens at the last
local niche where the species has lived, it goes extinct globally,
*really* extinct.
Nobody specified in advance that chordates and arthropods would be the
only two phyla of animals that adapted to life on dry land, much less
the particular adaptions each did in order to survive in that new
habitat. IMO arthropods were a natural for life on dry land because
they have an exoskeleton which should help retain moisture while still
allowing locomotion by joint in the exoskeleton. But it's rather
amazing that chordates could also evolve to survive on dry land. (And
in fact it was a rather torturous sequence of adaptions, first lung
fish who lived in the water but could breath air while not in water,
then amphibians who spent childhood in water as if eels but then lived
out of water as adults, and finally reptiles which encased eggs in
leather so they could be laid on dry land and avoid dehydration, and
which didn't hatch until the larval stage was finished and the adult
form was ready to emerge. I wonder which was the transitional form,
leathery eggs which hatched tadpoles which needed to immediately
squiggle to water after hatching, or soft eggs laid in water which
hatched adult forms which needed to immediately crawl out of the water
or swim to the surface of water to avoid drowning.)
As soon as mosses started living above the water line, why didn't
Echinoderms also evolve to scavanage the mosses, and gradually evolve
to live completely away from water (except that little bit of rain
water needed to keep mosses alive)? I see no specified-in-advance reason.
IDers don't have a problem with "specified complexity," they argue
that the neoDarwinian mechanism is insufficient to generate a
biological entity which exhibits such a characteristic.
Given that there's no such thing as specified complexity in the first
place, IDers are talking nonsense.
the neoDarwinian mechanism can only act on some structure or
function which already exists.
Agreed. If a new niche opens, but no existing structure of any local
species is easily/quickly adaptable to allow survival in the niche, the
niche remains unoccupied for a while, maybe for a long time.
After the very first tectonic plate buckling caused some ocean floor to
rise above the water level, forming the first dry land, how many
hundreds of millions of years did it take before some plants or animals
evolved to survive on dry land that was only occasionally moist from
recent rain?
This is one of the reasons Behe rationally argues that the
neoDarwinian mechanism is incapable of generating an irreducibly
complex biological entity which has no function until all the parts are
in place.
I agree with that hypothetical argument, but in fact evolution always
takes some other route, so his point is moot.
NS just tilts the allele frequencies of a species to circumvent
whatever limits the population size at a given moment.
That happens only if there's overlap between some existing allelles in
the local population and some portion of the local environment, such
that some individuals with those particular allelles can occupy that
portion of the local environment. (Think of the beachhead at Normandy
during WWII: Only a small part of Allied forces could occupy a small
portion of the beach, but that was sufficient to start the invasion.)
Then if the local environment is continuously varying with position,
fitness hill-climbing over time can allow the species to occupy more
and more of the local environment.
Iain couldn't produce or measure or observe any force labeled "NS"
which could do any such thing.
What one person can produce or measure or observe is pretty much
irrelevant to the issue of whether natural selection happens or not and
whether if it happens it's a cause of adaption. In fact mutation is
quite sufficient to introduce new allelles that have varying fitness
with respect to variations on the local environment, sometimes forcing
individuals to back off from the frontier, other times allowing
individuals to go where no species-mate has gone before into uncharted
local environment. And then due to competition for food, allelles in
less crowded regions replicate abundantly while allelles in more
crowded regions stagnate or die out, whereby the average is advanced
into the new frontier.
Next he seems to be under the mistaken belief that the goal of the
neoDarwinian mechanism's is to maximize a given population's size.
This is part of a Malthusian notion ...
You seem to be attacking a strawman. All that animals did under the
original Malthusian model was to try to survive themselves (and their
children and close relatives), whereby some were more successful than
others, whereby the more successful ones formed larger clades than the
less successful ones, whereby the average success rate improved over
time due to knocking out the less-successful ones and replicating the
more-successful ones. Maximizing the total population size of the
population isn't a goal, it's just the result of such selection.
Iain applies the concept of Natural Selection as if it were some sort
of naturalistic force with which he could make real deterministic-like
predictions. However only in the most simplistic of situations
(usually controlled experiments and thought experiments) is the
evolutionist able to predict much of anything about the change in
relative frequency of variations within a population let alone about
the emergence of new structures, new systems and new organisms. This
inability to make predictions is true whether or not the time frame is
relatively short or long.
I'll ignore the personal aspects of "Iain", and discuss only the
generally understood theory (as best I understand it anyway). Indeed if
you are expecting precise predictions of what mutations will happen,
hence what new allelles will be available for selection, hence which of
those new allelles will dominate due to the current environment, hence
specifically what direction evolution will go, new-Darwinian theory of
descent with modification via natural selection won't give you such
precise predictions. The best you can get is that if there is really
strong selection pressure, then surely evolution will produce some
adaption to that pressure, we just can't guess what specific allelles
will be responsible for that adaption, or even what general strategy
will be used.
For example, suppose you stress some critters by having their local
habitat get warmer and warmer toward eventually getting unbearably hot.
They might adapt by miagrating away and adapting to some new food that
is available in cooler regions. Or they might adapt by skurrying into
the hot region, grabbing food, and then skurrying back into the cool
region to eat it. Or they might adapt a way to store water and perspire
a lot in the hot region. Or they might adapt a way to pant rapidly to
get rid of excess heat via their exhalations. Or they might change
their metabolism to have stable chemicals at a higher temperature. You
can't predict which adaptive strategy will actually occur, although
prokaryotes tend to change their metabolism, and mammals tend to skurry
or pant or perspire, so the odds would be different depending on what
you started with. If they're human, they might not adapt themselves at
all, but instead engineer a way to bring in water or build shade or
build forced-air ventilation to cool the region back to the nice
temperature it was originally. Some insects also do forced-air
ventilation of their hives, using wings to force the air through.
Iain presumes the long discredited Malthusian notion that populations
must and will expand unabated until they consume all the available
resources unless stopped.
That's almost what does happen. Not all resources, but a vast majority
of easy-to-find resources, get exhausted, which finally starves the
population to reduce its growth. If food rebounds fast enough,
equilibrium is established. If food takes a long time to recover, then
there will be a major decline in population of our discussed species,
which will allow food to finally rebound, which will allow a new
population explosion, i.e. a longterm oscillation in both food and
discussed-species populations.
Iain has yet to demonstrate how the "work arounds" came to exist in
the first place.
Mutations, and sometimes recombinations.
in the case of Darwin's finches the variations in beak size already
existed within the population. All that occurred on the Islands during
Darwin's observations was a change in relative frequency of those beak
sizes.
I don't think you're correct. There was some variation in the ancestral
population, but isolated on the islands new allelles were generated by
mutations, and some of them allowed adaption to new kinds of foods not
previously eaten by finches.
..
.
- References:
- Prev by Date: Re: Carbon 14 Dating Post Mistake
- Next by Date: Re: Scant evolution evidence
- Previous by thread: Re: Iain doesn't understand "Complexity" and presumes a discredited Malthusian premise.
- Next by thread: Re: Iain doesn't understand "Complexity" and presumes a discredited Malthusian premise.
- Index(es):
Relevant Pages
|
