Darwinian evolution posits that beneficial genetic variations are
selected for reproductive success gradually, over geologic time, until
ultimately entirely new species emerge. To me it seems to best explain
the phenomena.  Within this context I have four questions:

1. Given that evolution is about adaptive complexity, leading to the
development of complex organs such as the eye, why don't we have
fossil evidence of intermediate forms of eye organs within a species?
I understand that eyes don't fossilize, but bony structures supporting
them do and the eye "socket" must have evolved through intermediate
forms. Why no evidence, except for variously developed eye organs
among different species?

2. Darwinism means gradualism. But in what sense could exceedingly
minute changes over eons be said to confer a survival advantage? For
example, the giraffe's long neck enables it to eat leaves higher up in
trees than can other animals. But if the neck evolved in minute
fractions of an inch at a time, how could such small changes over
immensely long time  confer an advantage that would then be chosen by
natural selection?

3. At the point that an individual of a new species actually evolves,
how does it find a mate to reproduce the new species? By definition,
species cannot interbreed. But wouldn't the odds be prohibitively
great that two or more individuals of a new species, both male and
female, would simultaneosly evolve at the same time and in the same
place?

4. In some sense selective breeding (artificial selection) can be used
to illustrate natural selection. I am puzzled as to how natural
selection accounts for new species. Has artificial selection resulted
in the creation of viable new species? For example, selective breeding
of dogs has produced an astonishing variety of dog types yet they are
all dogs, able to interbreed. One wonders why this long-practiced
selective breeding has not resulted in entirely new species that could
not breed with its parents or cousins but only with another individual
of its own species.

---

Request for Question Clarification by pafalafa-ga on 24 Nov 2006 18:05 PST

monreale-ga,

You've posted quite an intriguing set of questions.  I believe they
all can be satisfactorily answered from a biological viewpoint, but
doing so would take a good deal of effort for all four questions.

Why not just pick one question that's of most interest to you, so a
researcher could focus on that one.

It's not usually the case that four discrete questions on a complex
topic can get answered for the price you've set.


Just a suggestion...


pafalafa-ga

---

Clarification of Question by monreale-ga on 27 Nov 2006 20:32 PST

For:forcelli-ga

First, thanks for your thoughtful and interesting reponse. And rest
assured I am not a proponent of ID.

Your answer to my first question ("eyes") offers examples of light
sensitive organs in various existing species. But I was looking for
fossil evidence of the evolution of the complex eye within a SINGLE
species. Take humanoids. There is plenty of fossil evidence of
humanoids. But as far as I know, there is no fossil evidence of the
evolution of supporting eye structures. Even the earliest specimens
have an eye socket, hence had an eye. In fact, I am not aware of any
such evidence of intermediate eye forms for ANY species and I question
why this should be.

Re: question 2 ("giraffes"), in my view your answer, while not
compelling, is plausible.

Re: question 3 ("speciation", I like your example of the speciation of
populations. Is there fossil evidence you would cite of very closely
related species where one evolved from the other?

Re: question 4 ("dogs"). Here we have a situation where selective
breeding has forced evolution into warp-speed. And yet, despite
physical barriers due to size, all dogs can interbreed. I continue to
wonder why new species have not appeared. But let's shift from dogs
for a moment. Except, perhaps, for the simplest organisms in the
laboratory have we ever observed a new species appear anywhere?

Btw, unless someone else comes along with even better answers, at this
point I think you are the one most entitled to payment.

---

Clarification of Question by monreale-ga on 30 Nov 2006 11:02 PST

This is a second clarification. Note that I've increased payment from $20 to $30.

1.There are numerous examples of variously developed eye-type organs
among different currently existing species. As far as I know there is
NO evidence of the development of increasingly complex eye-organs,
i.e., their supporting structures, within a given species or its
precursors over evolutionary time. Apart from the easiest and most
often cited answer, the scarcity of the fossil record, is there any
other way to account for this?

2. Forcelli's answer is plausible and I accept it.

3. Forcelli's answer is a good one but, again, is there any fossil
evidence of very closely related species where one evolved from the
other?

4. Dogs are a single species sharing a common gene pool. They have
been selectively bred with a resulting astonishing variety of forms
over an infinitesmal span of time when compared to natural selection.
They are reproductively isolated insofar as breeders strive to keep
the breed "pure" and no breeder would artificially inseminate a
chihuhaua with a great dane. Given that this extraordinary variety of
dog breeds have been developed and that they are reproductively
isolated, is there any better answer to the fact that speciation has
not occurred other than simply "not enough time"? And leaving aside
dogs for a moment, what are the best examples that we've observed, in
the laboratory or elsewhere, of speciation actually occurring?

5. New question: It seems to me that none of the scenarios commonly
cited to account for speciation applies to the future evolution of the
human species, apart from a random advantageous, non-deleterious,
mutation (very rare) occuring simultaneously in some isolated human
population (extremely unlikely). Leaving aside the possibility of
humans colonizing beyond Earth, is there any likely scenario that
would lead to our existing human species evolving into a new species?

Just wanted to weigh in (briefly) on number 3. Relationships within a
species can be in flux so that some species-- which is a man-made
term, and Nature will have her fun-- are in the process of splitting.
A species can't come into being instantly, in theory, and so these new
and improved members will always have someone to, um, take out to
dinner.

On a side note, why is everyone so darned impressed with the eye?
Response to light is so amazingly basic that my begonia can do it, fer
goodness sakes, as can Donald Rumsfeld.

Now ears are another case. You wanna talk about amazing, talk about ears.

Mos tof what you ask sounds like a rehash of ID opposition to
evolution, and has been answered in  grea detail on many sites.
For the eye: http://www.pbs.org/wgbh/evolution/library/01/1/l_011_01.html
Giraffe: the idea that there can be no sudden jumps is mistaken. Many
single gene changes can produce dramatic alterations to morphology.
Speciation: markvmd has given the answer. Species are a human concept
and closely related plants and animals *do* interbreed, just not very
often
Dogs: see above. Also, when was the last chihuahua x St. bernard mating?

The eye cannot evolve...It has to be complete to function. At what
stage of evolution does the eye start to work AS AN EYE? Anything
previous and the creature would be blind. How would any creature
survive for the inordinate amount of time that evolutionists claim is
necessary for the 'system' to work?

(Hebrews 3:4) Of course, every house is constructed by someone, but he
that constructed all things is God.

(Romans 1:20) For his invisible [qualities] are clearly seen from the
world?s creation onward, because they are perceived by the things
made, even his eternal power and Godship, so that they are
inexcusable;

Q.E.D.

Whenever I see the handle pugwashjw65-ga in response to a science
question, I get annoyed.
I am annoyed right now.  Q.E.D. Science and religion need not be
mutually exclusive, but when bible-thumping evangalists try to inject
faith into a system of logic, both the scientist and the christian in
me are offended.


Wrong. Wrong. Wrong. Eyes can AND did evolve.

See the work of Dan-Erik Nilsson. 

Start with a flat patch of light sensative cells such as that seen in euglena.

Selection would favor the depression of the light sensative patch into
a cup. This is seen in planarium.

This allows the discrimintation of brightness in directions.

Now, if you constrict the opening (pin-hole camera style) this focuses
light more sharply on the photosensative cells.  Such eyes are seen in
the nautilus see snail.

Now, if you have an overgrowth of the pin-hole, you prevent
contamination, infestation. This is the first stage of a lens. A
division of this into layers, with liquid in between provided better
oxygenation and nutrition, it had the added advantage of functioning
as a bulging lens which now could sharply focus light on the
photoreceptor cells.

The notion that the eye is irreducibly complex is asanine. We can SEE
ealier phylogenies with primative eyes.

What we would consider a sub-optimal eye for us as humans, is
certainly not a sub-optimal eye for a sea slug or a flat worm.

Just because some individuals have a difficult time wrapping their
closed minds around the notion of the evolution of a structure doesn't
in any way shape or form diminish the fact that evolution is a well
supported part of science.

Okay now for the other three parts of your question:

2. Darwinism means gradualism. 

Yes, but this also entails discete changes in phenotype. 
 
For example, the giraffe's long neck enables it to eat leaves higher up in
trees than can other animals. But if the neck evolved in minute
fractions of an inch at a time, how could such small changes over
immensely long time  confer an advantage that would then be chosen by
natural selection?

-- Imagine a longer neck, being selected for slowly over time.  Each
time a longer neck popped up, the animal would have marginal increases
in access to food.  This certainly WOULD take a long time, but with
increases in neck lenght selected for with each marginal increase, it
would be favored over eons.

3. At the point that an individual of a new species actually evolves,
how does it find a mate to reproduce the new species? By definition,
species cannot interbreed. But wouldn't the odds be prohibitively
great that two or more individuals of a new species, both male and
female, would simultaneosly evolve at the same time and in the same
place?

-- Speciation isn't the gray line that the textbooks might have one
assume.  There isn't an over-night shift, but rather a gradual
divergance of one species into two.  There will come a point, perhaps
well after the animals have been seperated geographically, or by
activity rythms, or so on, that they would not be able to produce
viable, offspring.  They could look really different and be
biologically very different by that point. So, an individual alone,
cannot be a new species. A population of individuals can speciate.

4. In some sense selective breeding (artificial selection) can be used
to illustrate natural selection. I am puzzled as to how natural
selection accounts for new species. Has artificial selection resulted
in the creation of viable new species? For example, selective breeding
of dogs has produced an astonishing variety of dog types yet they are
all dogs, able to interbreed. One wonders why this long-practiced
selective breeding has not resulted in entirely new species that could
not breed with its parents or cousins but only with another individual
of its own species.

---Imagine the following:  We start with a population of mammals, that
scurry around on the ground.  There is a mutation which results in the
shift of the active cycle of an animal by a few hours, so that they it
is active later in the day, and also at night.  This animal isn't
geographically, or temporally seperated from the rest of the species
in terms of the reproductive time.  (Lets say they mate in the
afternoons).  This shift of the active cycle is favorable, because
this animal now is active later, when the sun is lower, so predators
have a hard time seeing it. It mates with another animal which is
active on the "normal" cycle, but now, some of the offspring are
active later too.  They have an advantage to survive and mate, because
they aren't eaten as often.  So, this late-shift provides a selective
advantage, and becomes prevelant in the population. This happens again
and again over time, until we have two groups, one which is day-active
and one which is night-active. These animals aren't active during each
others mating times, and hence have a temporal barrier to
reproduction.  They continue to accrue differences over time, to the
point, where if we took one animal from each group, they couldn't
produce offspring with each other (lets say due to immune reactions).

As for dogs, there are certainly some cases where dog breeds are
moving down the line towards speciation. Think about a great dane and
a daschund.  In nature, they cannot mate due to physical constraints. 
Over time, perhaps, even artificial insemination would fail to result
in a viable puppy.  This is a gradual process. and while we have been
interbreeding dogs for years, evolution works on a very long time
scale.

One additional comment:

I am offended as a Christian by intellegent design and anti-evolution
as well as as a scientist here is why:

1) I don't believe in a stupid God.  I don't believe that answers to
life need to be simple.
2) I don't believe that anything can be gained by reductio ad
absurdum. Which is what intellegent design is.
3) Science is based on logic, religion on faith.  One shouldn't be
used to answer the question of the other.  This is a violation of the
logic inherant to the philosophy of science and the philosophy of
faith.
4) This sort of discourse attempts to make scientists look amoral and
religious persons stupid.  Neither is necessarily true.

Forcelli-ga: Just wanted to make sure you saw my "clarification"
above, which I noticed was addressed to another commentator.

BTW, most discussions of evolution specifically disregard domestic
animals and plants.

Speciation has been documented, for example, in the hawthorn fly which
is believed to be undergoing sympatric speciation, a complex process
involving  multilocus genetics, and other animals as well. It has also
been shown in various plants.

As far as the giraffe thing-- a giraffe with a one-inch longer neck
would have had a bit more food than everyone else, allowing it more
time to reproduce (or to be more attractive to the opposite sex) and
thus pass those genes on.  Forcelli-ga is correct about this.

I agree with mikewa that not all dogs can mate.  My chihuahua would
not be able to physically mate with many dog species, and they with
her.

pugwashjw65--  The eye can evolve just as anything else. Evolution is
simply the passing on of traits that allow people to reproduce
better/more.  It makes complete sense that the people with more
attractive or helpful mutations are the ones whose genes are selected
for the next generation.  At some point, there was possibly an eye
that didn't work.  Then someone had a mutation and could see out of
the eye.  That was a very helpful trait and got passed on because that
person could get more food and therefore live to have more children
and more genes passed on, yada yada yada.  Pretty simple stuff.

keystroke and others,

On the topic of which dogs can mate with which, you're absolutely
right that a chihuahua and a great dane can't quite, er, get it
together on the mating front.

However, both dogs can readily mate with intermediate-sized dogs, and
the mid-sizers can then pass genes along to the larger or smaller
populations.

As long as genes can readily pass from chihuahuas to great danes, even
through one or more intermediates, then they are the same species. 
It's the gene transfer more than the physical act of mating that is
key to the concept of a species...at least from a biological point of
view.

Just an FYI,

paf

pafalafa
Yes, of course dogs share a common gene pool, which is why they are
considered one species. The point of the chihuahua example is that
speciation could easily occur if a small population containing only
the extreme forms became isolated

There is only one major anomaly in all the four arguments and I am
really surprized that none of the "experts" could see it. It is the
scale of time over which evolution occurs. (Read Dawkins). You will
never find differential socket designs within the "humanoid" race,
because of the extremely short period of time we've been here (on
earth), a time period in which you will also not find reproductively
isolted human species...even artificial selection would need many,
many generations to allow reproductive isolation...the giraffe
question is a trifle inane, in so much that you cannot only consider
the trophic advantage that a longer organ (!) provides to the bearer;
there will also most certainly be a reproductive (tribak mating)
advantage, among other socially (within  giraffe socities
i.e.)relevant advantages (think akin to plumage in peacocks...) but
again the enormity of the time scale involved is the main clue...and
the query about "the point in time " of the emerge on one species is
extremely inane; please read Origin of Species and try an understand
the conept of the finch evolution; for reporductive isolation to
result in speciaion, a number of other factors must prevail, but apart
from that it is not the differential evolution of individuals (and
hence "male" or "female") that is being anaylsed but the differential
evolution of a population (a collection of individuals, i.e. both
"males" and "females") when comapred with another population with
similar characteristics, geographically separated from each other over
a long epoch (many generational orders).

I apologize if I am a bit aggressive and angered, but I am extremely
astonished at the notions of evolution that people seem to carry
around. I sincerely hope that before opinions are formed and
expostulated (especially about scientific concepts), the facts and
arguments be seriously and diligently studied. I think the closest
answer to the evolution of the a light-senitive receptor that was
later cetralized and co-ordinated with the nervous system was the one
provided by forcelli. And I was shocked to read the counetr question
rasied by the original commentator:why are there no architechtural
differences in eye socket-designs within human"oid"s?

Hi ashimmalhotra-ga,

You may want to temper your anger. An honestly asked question deserves
an objective answer.

I don't know that I'd recommend Dawkins. He's a great popularizer of
science but a mediocre biologist.

It is entirely possible to get radical developmental changes in a
short amount of time (eg thr eye socket example). However, most of
these changes are not advantageous, pleiotropic  (making them not
avantageous or more likely deleterious) and are therefore not passed
on.

Also you may want to do some critical reading on sexual selection.
There is not universal acceptance that sexual selection is responsible
for maintenance of extreme traits (peacocks feathers)

Also I don't agree that asking when speciation occurred is inane.
There are many labs looking at genetic differences between closely
related species to try and determine what was the critical change that
lead to the split.

-dops

I see that my questions have raised some heat as well as light. I
won't respond in kind. Again, I accept Darwinian evolution as the best
current explanation of the phenomena. I have argued against ID within
my own family. Granted, my biological education is limited (I
dissected a fetal pig 40 years ago as a freshman!) so I'll
occasionally use words such as "humanoid" vs "hominid". But I've read
and thought on the subject of evolution and I'm trying to learn more
from you, the experts. Forcelli has come closest to giving me the
understanding I seek so I'd like to see him return to the dialogue but
Im prepared to be closely attentive to anyone. Note that I've
increased the payment from $20 to $30.