[extropy-chat] Re: intelligent design homework

Tue Aug 9 11:13:38 UTC 2005

--- Robert Lindauer <robgobblin at aol.com> wrote:

> What we're
> trying to get at is 
> large-scale adaptations on the order of
> Rhinoceros-elephant splits 
> where the early rhino-fant was split into to two
> "subspecies" with only 
> mildly different genetic profiles.   The elephants
> got trunks, the 
> rhinos got horns, say.  At some point, though, some
> particular 
> rhinofant is no longer able to reproduce with its
> cousins.

Only pre-genomic era biologists, working entirely on
morphology, would place elephants in the same clade as
rhinos. Phylogenetically, elephants are more closely
related to manatees and sea cows than they are to
rhinos. Rhinos are more closely related to lions and
zebras than they are to elephants. 
http://physwww.mcmaster.ca/~higgsp/Phylogeny.htm

Convergent evolution is a tricky and misleading
phenomenon. But barring your incorrect example, I see
the argument you are trying to make. I will try as
briefly as I can to show you how speciation works.

Lets say you have two related but mating incompatable
species the jabberwocks and the bandersnatches. Now
both bandersnatches and jabberwocks are ferocious
carnivorous reptiles that descended from a common
ancestor: the humble insect eating slithy tove.
At first there are only slithy toves and they live in
an envoronment called the wabe where they gyre and
gimble.

Now the first thing you must note is that there are
several varieties of mutation. Aneuploidy, gene
deletion, gene duplication, chromosomal tranlocations,
transposons, retroviruses, and some simple single base
pair mutations.

Now in any eukaryotic organisms (i.e. anything more
complex than a bacterium or an archaea) a large
majority of the genome consists of intergenic regions
of so-called junk DNA. Which aren't really junk, but
they doesn't encode genes either. Moreover the genetic
code is degenerate and redundant which means that you
can often change the 2 out the 3 bases that code for
an amino acid without changing the amino acid. 

Because of these facts, it is a misconception that the
vast majority of mutations are deleterious. Instead
the vast majority of mutations are silent meaning they
have absolutely no effect on the relative fitness of
the organism. Of the remaining mutations a large
number are minutely beneficial or minutely
deleterious. Only a handful are extremely damaging or
extremely beneficial. 

Keep in mind, I am not talking about dumping plutonium
into the wabe here, I am talking about natural normal
mutation rates which are governed by such factors as
the amount of repair enzymes in germline cells and
other regulatory mechanisms. Now every so often a
slithy tove is born with a mutation in one of its
genes that encodes for a larger sturdier hip that
allows them to run after flying insects on their hind
legs. 

While some others get born with stronger claws that
help them burrow for insects. With no natural
predators in the swampy morass of the wabe, a fair
number of these mutations go by unoticed. And they are
all still interbreeding such that 80% of them are
"normal", 10% have strong hips, and 10% of them
burrow.

Many generations go by and then the weather changes a
little and the wabe becomes a somewhat milder climate.
Now the happy paradise of the slithy toves is lost
because the voracious jubjub bird has moved in to
wabe. Now after several more generations of being
preyed upon by jubjub birds, the wabe is a very
different place. 

The burrowing toves have been succesful because they
could burrow away from the jubjub bird. The running
toves are successful because they can run away from
the jubjub birds. While the poor slithy toves that can
only gyre and gimble are being decimated by the
voracious jubjub birds. So now the population is 40%
burrowing toves, 40% running toves, and only 20%
slithy toves.

While it is still possible for the various toves to
interbreed, they almost never do because the none of
the other toves will stop digging or stop running long
enough to mate with the poor slithy toves. Moreover
the burrowers have evolved an acute sense of smell to
find their food and their mates underground. So male
burrowing toves just LOVE the stinky females because
he can find them in the dark.

While on the surface, the female running toves really
LOVE the big bright colorful males because any male
that can be bright blue in a jubjub bird infested
swamp must really be able to run fast. To neither
subspecies is the slithy tove any longer at all
sexually attractive because well its to busy getting
eaten to mate.

A few more thousands of generations go by. Some
mosquitos bearing west nile virus move into the wabe.
There is a plague amongst the jubjub birds and their
ranks start to thin out. The slithy toves are nearly
extinct now. The running toves have become larger and
faster spending more time running around searching for
prey. The burrowing toves have become larger and have
grown long sharp teeth in addition to their burrowing
grasping claws. 

Futhermore unbeknownst to any of the creatures
concerned because it is a SILENT mutation to the their
respective gene pools, somewhere down the line the
acrosomes on the egg cells of the females have changed
in all 3 species such that they can no longer
interbreed. The sperm just can't fertilize the eggs of
the other species any longer. Not that the burrowing
or running descendants of the toves would want to
since they are so different now any way. 

A few more thousands of generations go by, the slithy
toves are make a slight comeback because the jubjub
birds have all been wiped out. But because of the
progressively cooler climate and the sheer efficiency
of the burrowers and the runners, insects have been
becoming more scarce. Thus the burrowers have become
still larger so that they can eat more types of prey
like the large borogoves, and occasionally the now
rare jubjub birds, the pitiful slithy toves. In short,
they have become full fledged jabberwocks. The runners
have also become larger and more frumious and have
become bandersnatchs, and relish chasing down large
mome raths to feast upon.

     Notice that at no time was there an intelligent
designer or "mules" involved in the evolution of the
ecology of the wabe. Just mutation, environmental
change, and adaptation. 

The Avantguardian 
is 
Stuart LaForge
alt email: stuart"AT"ucla.edu

"The surest sign of intelligent life in the universe is that they haven't attempted to contact us." 
-Bill Watterson

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