Just curious
Don
another board and was wondering what the answers are:
Ten Questions to Ask Your Biology Teacher about Evolution
------------------------------------------------------------
--------------------
ORIGIN OF LIFE. Why do textbooks claim that the 1953
Miller-Urey experiment shows how life's building blocks may
have formed on the early Earth -- when conditions on the
early Earth were probably nothing like those used in the
experiment, and the origin of life remains a mystery?
DARWIN'S TREE OF LIFE. Why don't textbooks discuss the
"Cambrian explosion," in which all major animal groups
appear together in the fossil record fully formed instead of
branching from a common ancestor -- thus contradicting the
evolutionary tree of life?
HOMOLOGY. Why do textbooks define homology as similarity due
to common ancestry, then claim that it is evidence for
common ancestry -- a circular argument masquerading as
scientific evidence?
VERTEBRATE EMBRYOS. Why do textbooks use drawings of
similarities in vertebrate embryos as evidence for their
common ancestry -- even though biologists have known for
over a century that vertebrate embryos are not most similar
in their early stages, and the drawings are faked?
ARCHAEOPTERYX. Why do textbooks portray this fossil as the
missing link between dinosaurs and modern birds -- even
though modern birds are probably not descended from it, and
its supposed ancestors do not appear until millions of years
after it?
PEPPERED MOTHS. Why do textbooks use pictures of peppered
moths camouflaged on tree trunks as evidence for natural
selection -- when biologists have known since the 1980s that
the moths don't normally rest on tree trunks, and all the
pictures have been staged?
DARWIN'S FINCHES. Why do textbooks claim that beak changes
in Galapagos finches during a severe drought can explain the
origin of species by natural selection -- even though the
changes were reversed after the drought ended, and no net
evolution occurred?
MUTANT FRUIT FLIES. Why do textbooks use fruit flies with an
extra pair of wings as evidence that DNA mutations can
supply raw materials for evolution -- even though the extra
wings have no muscles and these disabled mutants cannot
survive outside the laboratory?
HUMAN ORIGINS. Why are artists' drawings of ape-like humans
used to justify materialistic claims that we are just
animals and our existence is a mere accident -- when fossil
experts cannot even agree on who our supposed ancestors were
or what they looked like?
EVOLUTION A FACT? Why are we told that Darwin's theory of
evolution is a scientific fact -- even though many of its
claims are based on misrepresentations of the facts?
wf...@ptd.net
wrote:
>I'm no expert on this but I'm curious ... I saw this post on
>another board and was wondering what the answers are:
>
>
the answer is that this is standard creationist propaganda dealt with
about 10 yrs ago...see the talk.origins FAQ.
>Ten Questions to Ask Your Biology Teacher about Evolution
>
>------------------------------------------------------------
>--------------------
>
>ORIGIN OF LIFE. Why do textbooks claim that the 1953
>Miller-Urey experiment shows how life's building blocks may
>have formed on the early Earth -- when conditions on the
>early Earth were probably nothing like those used in the
>experiment, and the origin of life remains a mystery?
like this crap. those of us who are chemists understand that
miller/urey was designed to be a first approach to evaluating theories
about life's origins....not a definitive 'cause and effect' final
test. i guess this crap shows why creationists have a dim view of
science.
>
>DARWIN'S TREE OF LIFE. Why don't textbooks discuss the
>"Cambrian explosion," in which all major animal groups
>appear together in the fossil record fully formed instead of
>branching from a common ancestor -- thus contradicting the
>evolutionary tree of life?
uh, AFAIK, most textbooks DO discuss the cambrian explosion, and the
fossils dont appear 'fully formed'. in addition, the CE took place
over 5-15 million yrs....not 'suddenly' as creationists say.
>
>HOMOLOGY. Why do textbooks define homology as similarity due
>to common ancestry, then claim that it is evidence for
>common ancestry -- a circular argument masquerading as
>scientific evidence?
i guess when creationists get all pup tent over the idea of 'circular
arguments' they forget a key prediction of evolution was homology. in
fact, evolution was accepted long before darwin based partially on
homology.
>
>HUMAN ORIGINS. Why are artists' drawings of ape-like humans
>used to justify materialistic claims that we are just
>animals and our existence is a mere accident -- when fossil
>experts cannot even agree on who our supposed ancestors were
>or what they looked like?
'materialistic claims'?? have there been any UNMATERIALISTIC claims in
ANY science? physics? chemistry? geology? if so, please provide
details on this earthshattering discovery.
>
>EVOLUTION A FACT? Why are we told that Darwin's theory of
>evolution is a scientific fact -- even though many of its
>claims are based on misrepresentations of the facts?
>
who is 'we'? only if you mean the terminally stupid...
--------------------
To find out who 'wf3h' is, go to 'qrz.com'
and enter 'wf3h' in the field.
John Mott
: ORIGIN OF LIFE. Why do textbooks claim that the 1953
: Miller-Urey experiment shows how life's building blocks may
: have formed on the early Earth -- when conditions on the
: early Earth were probably nothing like those used in the
: experiment, and the origin of life remains a mystery?
unsubstantiated assertion
:
: DARWIN'S TREE OF LIFE. Why don't textbooks discuss the
: "Cambrian explosion," in which all major animal groups
: appear together in the fossil record fully formed instead of
: branching from a common ancestor -- thus contradicting the
: evolutionary tree of life?
unsubstantiated assertion
:
: HOMOLOGY. Why do textbooks define homology as similarity due
: to common ancestry, then claim that it is evidence for
: common ancestry -- a circular argument masquerading as
: scientific evidence?
unsubstantiated assertion
:
: VERTEBRATE EMBRYOS. Why do textbooks use drawings of
: similarities in vertebrate embryos as evidence for their
: common ancestry -- even though biologists have known for
: over a century that vertebrate embryos are not most similar
: in their early stages, and the drawings are faked?
unsubstantiated assertion
:
: ARCHAEOPTERYX. Why do textbooks portray this fossil as the
: missing link between dinosaurs and modern birds -- even
: though modern birds are probably not descended from it, and
: its supposed ancestors do not appear until millions of years
: after it?
unsubstantiated assertion
:
: PEPPERED MOTHS. Why do textbooks use pictures of peppered
: moths camouflaged on tree trunks as evidence for natural
: selection -- when biologists have known since the 1980s that
: the moths don't normally rest on tree trunks, and all the
: pictures have been staged?
unsubstantiated assertion
:
: DARWIN'S FINCHES. Why do textbooks claim that beak changes
: in Galapagos finches during a severe drought can explain the
: origin of species by natural selection -- even though the
: changes were reversed after the drought ended, and no net
: evolution occurred?
unsubstantiated assertion
:
: MUTANT FRUIT FLIES. Why do textbooks use fruit flies with an
: extra pair of wings as evidence that DNA mutations can
: supply raw materials for evolution -- even though the extra
: wings have no muscles and these disabled mutants cannot
: survive outside the laboratory?
unsubstantiated assertion
:
: HUMAN ORIGINS. Why are artists' drawings of ape-like humans
: used to justify materialistic claims that we are just
: animals and our existence is a mere accident -- when fossil
: experts cannot even agree on who our supposed ancestors were
: or what they looked like?
unsubstantiated assertion
:
: EVOLUTION A FACT? Why are we told that Darwin's theory of
: evolution is a scientific fact -- even though many of its
: claims are based on misrepresentations of the facts?
unsubstantiated assertion
:
:
Richard S. Norman
wrote:
>Ten Questions to Ask Your Biology Teacher about Evolution
>ORIGIN OF LIFE.
>DARWIN'S TREE OF LIFE.
>HOMOLOGY
>VERTEBRATE EMBRYOS
>ARCHAEOPTERYX
>PEPPERED MOTHS
>DARWIN'S FINCHES
>MUTANT FRUIT FLIES
>HUMAN ORIGINS
All these questions relate to what textbooks supposedly
claim about evolution.
>EVOLUTION A FACT? Why are we told that Darwin's theory of
>evolution is a scientific fact -- even though many of its
>claims are based on misrepresentations of the facts
One question to ask your creationist about evolution:
Why are all of your questions based on misrepresentations
of the facts?
Here are some particulars:
Have you ever looked at what textbooks actually say?
Have you looked at how textbooks have changed over the decades?
Have you looked at real expositions of evolution in the primary
scientific literature and understood that introductory textbooks
necessarily show only an abbreviated version of current
knowledge?
Dana Tweedy
"Don" <dbi...@elkgrove.net> wrote in message news:3d0b...@207.173.96.5...
> I'm no expert on this but I'm curious ... I saw this post on
> another board and was wondering what the answers are:
Glad to see you realize that there ARE answers to these questions. You
should also realize that many of these "questions" are loaded, and are
misrepresentations themselves.
>
>
> Ten Questions to Ask Your Biology Teacher about Evolution
>
> ------------------------------------------------------------
> --------------------
>
> ORIGIN OF LIFE. Why do textbooks claim that the 1953
> Miller-Urey experiment shows how life's building blocks may
> have formed on the early Earth -- when conditions on the
> early Earth were probably nothing like those used in the
> experiment, and the origin of life remains a mystery?
First of all, the origin of life is not strictly evolution. It's a separate
field of study, referred to as "Abiogenesis". To answer the question,
because the Miller-Urey experiment does show that amino acids can and do
form by natural processes. The origins of life are still a mystery, but
there has been progress in this field, and some promising lines of research
are being followed.
>
> DARWIN'S TREE OF LIFE. Why don't textbooks discuss the
> "Cambrian explosion," in which all major animal groups
> appear together in the fossil record fully formed instead of
> branching from a common ancestor -- thus contradicting the
> evolutionary tree of life?
Loaded question. First of all, most good biology textbooks DO discuss the
Cambrian explosion, and no, not all major animal groups appear together at
this time. Fossils from the Cambrian period do not have, for example any
reptiles, amphibians, mammals, birds, or any land invertibrates. All
fossils are "fully formed" as they are remains of plants and animals that
were alive at one time. No one expects to find a fossil of a less than
"fully formed" organism. Furthermore the "Explosion" took place over
several MILLION years, rapid in geologic terms, but not on an evolutionary
scale.
>
> HOMOLOGY. Why do textbooks define homology as similarity due
> to common ancestry, then claim that it is evidence for
> common ancestry -- a circular argument masquerading as
> scientific evidence?
Again, the question is loaded. Most textbooks do not define homology as
similarity due to common ancestory. Common ancestory is an inference from
homology, not a definition of it.
>
> VERTEBRATE EMBRYOS. Why do textbooks use drawings of
> similarities in vertebrate embryos as evidence for their
> common ancestry -- even though biologists have known for
> over a century that vertebrate embryos are not most similar
> in their early stages, and the drawings are faked?
The textbooks I have seen use photographs, not drawings. Vertibrate embryos
are similar at certain stages, and yes, although Haeckel did fudge his
drawings to support his belief in recapitulation, embryology does give
evidence of common ancestory. It should also be noted that many textbook
writers and editors have been known to be lazy, and copy their material from
earlier editions. This is a failing of the textbook industry, rather than
science.
>
> ARCHAEOPTERYX. Why do textbooks portray this fossil as the
> missing link between dinosaurs and modern birds -- even
> though modern birds are probably not descended from it, and
> its supposed ancestors do not appear until millions of years
> after it?
Because it's a very good example of a transitional fossil, something that
Creationists claim does not exist. Archy may not have been in the direct
line that led to modern birds, but it was similar to the kind of creature
that was. As for the second part of the question, I don't know what
"ancestors" they are talking about.
>
> PEPPERED MOTHS. Why do textbooks use pictures of peppered
> moths camouflaged on tree trunks as evidence for natural
> selection -- when biologists have known since the 1980s that
> the moths don't normally rest on tree trunks, and all the
> pictures have been staged?
Because it's a good example of how natural selection works. The moths were
photographed to show the visibility of the different morphs on different
backgrounds. The moths do rest on tree trunks, at least some of the time,
where they would stand out for predation. No one claimed that the moths
habitually lived on the tree trunks.
>
> DARWIN'S FINCHES. Why do textbooks claim that beak changes
> in Galapagos finches during a severe drought can explain the
> origin of species by natural selection -- even though the
> changes were reversed after the drought ended, and no net
> evolution occurred?
The beak sizes and shapes changing in populations due to enviromental
changes are a good example of evolution. Evolution is not toward any goal
other than immediate survival. How can they claim no "net evolution"
occured, when beak size and shape changed TWICE, in response to the
enviroment?
>
> MUTANT FRUIT FLIES. Why do textbooks use fruit flies with an
> extra pair of wings as evidence that DNA mutations can
> supply raw materials for evolution -- even though the extra
> wings have no muscles and these disabled mutants cannot
> survive outside the laboratory?
Because it shows that change can occur. Evolution is change, not
improvement. It doesn't matter if those flies could or could not survive
outside a lab. They survived IN the lab. Evolution is only concerned with
the "here and now", not survival elsewhere.
>
> HUMAN ORIGINS. Why are artists' drawings of ape-like humans
> used to justify materialistic claims that we are just
> animals and our existence is a mere accident -- when fossil
> experts cannot even agree on who our supposed ancestors were
> or what they looked like?
Because 1. we are animals (wether we are "just" animals is another matter)
2. No one says our existance is a "mere accident" 3. All science is
materialistic, as everything is made up of matter. Please give an example
of a science that is NOT materialistic. Artists conceptions are
illustrations that are known to be speculative, but are based on physical
evidence. Experts may disagree on exactly how to piece together the hominid
family tree, but they agree that we did in fact have ancestors that are more
ape like the farther back towards our common ancestor with Chimps.
>
> EVOLUTION A FACT? Why are we told that Darwin's theory of
> evolution is a scientific fact -- even though many of its
> claims are based on misrepresentations of the facts?
Because evolution is a fact. The misrepresentations are almost exclusively
on the Creationist side. Please understand that an idea can be both a fact
and a theory at the same time.
DJT
>
>
Richard Clayton
You miss the point. Picture a student coming to class with these ten
questions written down to ask his teacher. Imagine him raising his hand
for permission to speak and then reading them off one at a time.
Yes, a high school science teacher could respond that each of them
are mere "unsubstantiated assertions." Better still, the teacher could
explain the logical and scientific fallacies in each one. ("It doesn't
matter whether or not archaeopteryx was a DIRECT ancestor of modern
birds. The tree of life has many branches, not all of which survive
indefinitely. The important thing is that it's a true _transitional
form_-- a bird lacking many typical bird features while also possessing
numerous distinctly reptilian features.")
Now look at it from the point of view of the students. If the
teacher merely dismisses the questions with a reply of "unsubstantiated
assertion," the students will (correctly) interpret that as handwaving.
On the other hand, if the teacher answers each question in careful
detail, the kid with the question list can declare "Wow, evolutionists
sure have to work HARD to answer these simple questions!" In short, this
is the same kind of propaganda used by Gish, Hovind, and their ilk--
they don't give a wet slap about science or honesty; they merely want to
create enough verbal sleight-of-hand to make sure the flock stays
fleeced.
IMHO, perhaps the best response of all for the hypothetical biology
teacher would be to explain why each one of those is a very loaded
question, if not completely dishonest-- similar to asking somebody "Are
you STILL beating your wife?"
($0.02 deposited)
--
Richard Clayton (for...@earthlink.net)
"You were unlucky, but not terribly so. Be thankful, because eventually
you'll be very unlucky. In the end, everyone's score is zero." --
Stephen Lea Sheppard
Boikat
> another board and was wondering what the answers are:
>
>
> Ten Questions to Ask Your Biology Teacher about Evolution
>
> ------------------------------------------------------------
> --------------------
>
> ORIGIN OF LIFE. Why do textbooks claim that the 1953
> Miller-Urey experiment shows how life's building blocks may
> have formed on the early Earth -- when conditions on the
> early Earth were probably nothing like those used in the
> experiment, and the origin of life remains a mystery?
The early conditions were similar.
>
> DARWIN'S TREE OF LIFE. Why don't textbooks discuss the
> "Cambrian explosion," in which all major animal groups
> appear together in the fossil record fully formed instead of
> branching from a common ancestor -- thus contradicting the
> evolutionary tree of life?
Textbooks do address the "Chambrian Explosion". The 'problem" is that the
early "common ancestor" was probably soft bodied, and no likely fossilized,
not to mention, existed so long ago that if the early "trunk" was
fossilized, it also stands a good chance of having been erroded or
subducted, or just has not been found yet. A lot can happen in the course of
a billion years or so.
>
> HOMOLOGY. Why do textbooks define homology as similarity due
> to common ancestry, then claim that it is evidence for
> common ancestry -- a circular argument masquerading as
> scientific evidence?
No, the homology was noticed first, then came the hypothesis of common
descent, and subsequent investigation supported the hypothesis.
>
> VERTEBRATE EMBRYOS. Why do textbooks use drawings of
> similarities in vertebrate embryos as evidence for their
> common ancestry -- even though biologists have known for
> over a century that vertebrate embryos are not most similar
> in their early stages, and the drawings are faked?
>
Because the drawings swere not faked, just exagerated, and because there are
similarities. The whole "faked embryology" claim is an attempt to make a
mountain out of a mole hill.
> ARCHAEOPTERYX. Why do textbooks portray this fossil as the
> missing link between dinosaurs and modern birds -- even
> though modern birds are probably not descended from it, and
> its supposed ancestors do not appear until millions of years
> after it?
Because it contains both characteristics of birds and other theropod
dinosaurs, and the claim of "it's supposed ancestors do not appear until
millions of years after it" sounds like a bogus claim.
>
> PEPPERED MOTHS. Why do textbooks use pictures of peppered
> moths camouflaged on tree trunks as evidence for natural
> selection -- when biologists have known since the 1980s that
> the moths don't normally rest on tree trunks, and all the
> pictures have been staged?
The pictures were "staged" since moths do not normally pose for
photographers.
>
> DARWIN'S FINCHES. Why do textbooks claim that beak changes
> in Galapagos finches during a severe drought can explain the
> origin of species by natural selection -- even though the
> changes were reversed after the drought ended, and no net
> evolution occurred?
Suppose the dorught had not ended?
>
> MUTANT FRUIT FLIES. Why do textbooks use fruit flies with an
> extra pair of wings as evidence that DNA mutations can
> supply raw materials for evolution -- even though the extra
> wings have no muscles and these disabled mutants cannot
> survive outside the laboratory?
1) Citation for lack of muscles?
2) the fact that the malformed fruitfly cna live *in* the lab, yet not
*outside* the lab would seem to support natural selection, no?
>
> HUMAN ORIGINS. Why are artists' drawings of ape-like humans
> used to justify materialistic claims that we are just
> animals and our existence is a mere accident -- when fossil
> experts cannot even agree on who our supposed ancestors were
> or what they looked like?
Because 1) we are animals, but the claim of "mere accident" is misleading.
Besides, the illustrations are designed to show how hominids have changed
through the ages, not to justify materialism or the process by which those
changes came about. The second point is misleading.
>
> EVOLUTION A FACT? Why are we told that Darwin's theory of
> evolution is a scientific fact -- even though many of its
> claims are based on misrepresentations of the facts?
Because evolution is both a fact (a recognized ohenomena), and a theory (the
body of explainations used in an attempt to explain the observed phenomena).
Also, it would be nice to see one true example of a "misrepresention of the
facts" that are supposedly used to support evolution that is current and is
indeed a misrepresentation of the facts, rather than misrepresentations of
the facts by creationist scum.
Boikat
Herb Martin
> teacher would be to explain why each one of those is a very loaded
> question, if not completely dishonest-- similar to asking somebody "Are
> you STILL beating your wife?"
Yes.
Were this to happen to me, I would probably do that
and explain the facts but before the facts there would
be ONE HECK of a HOMEWORK assignment for that
student <GRIN>
If you ask a stupid question you need to help find out
the answer.
And there are stupid questions -- when the student doesn't really
want the answer, is trying to show off, is trying to embarrass the
teacher, is asking a question that is off-topic, or is parroting what
someone else said without engaging the brain are all possible
elements in a stupid question.
> ($0.02 deposited)
I thought we are supposed to pay YOU?
Herb Martin
Try ADDS for great Weather too:
http://adds.aviationweather.noaa.gov/projects/adds
Mike the Vike
extra credit to find the answers on his or her own and report back to the
class on it.
Telling kids the answers is like feeding them fish instead of teaching them
how to fish and survive on their own.
Giving a student who comes in with these questions the answers will make you
look smarter to the other students, but it will not in the long run teach
the student anything.
Adam Marczyk
> another board and was wondering what the answers are:
What other board? We'll go and set 'em straight. ;)
> Ten Questions to Ask Your Biology Teacher about Evolution
Ah, Jonathan Wells, is it? Well, he certainly is no problem to debunk. Here are
the long answers to these questions:
http://talkorigins.org/faqs/wells/
I'll give the abridged versions in this post.
> ORIGIN OF LIFE. Why do textbooks claim that the 1953
> Miller-Urey experiment shows how life's building blocks may
> have formed on the early Earth
The Miller-Urey experiment demonstrates exactly what it was intended to
demonstrate: that the simple chemical building blocks of life (amino acids,
among others) form by themselves very simply under the right conditions.
> -- when conditions on the
> early Earth were probably nothing like those used in the
> experiment,
This is false. Evidence indicates that the prebiotic atmosphere was not quite as
strongly reducing as that used in Miller-Urey, but even a weakly reducing
atmosphere would still be able to produce a lot of simple organic chemicals.
> and the origin of life remains a mystery?
Creationist God-of-the-Gaps reasoning: We don't understand it, so it must be a
miracle. While we don't know the exact reaction pathways, enormous amounts of
progress have been made in understanding the origin of life -- for example,
there is now broad consensus that early life at some point passed through a
pure-RNA stage -- and there's no reason to believe that the problems still
remaining will prove any more intractable than the ones already solved.
> DARWIN'S TREE OF LIFE. Why don't textbooks discuss the
> "Cambrian explosion," in which all major animal groups
> appear together in the fossil record fully formed instead of
> branching from a common ancestor -- thus contradicting the
> evolutionary tree of life?
"All major animal groups" is a flat-out lie. To name just one example, there
were no vertebrates in the Cambrian -- that means no birds, no amphibians, no
fish, no reptiles, and no mammals. There were potential *ancestors* of
vertebrates -- quite bizarre wormlike animals with primitive spinal cords,
nothing at all like what exists today -- but that's it. Similar statements hold
true for other major groups: their distant ancestors existed, but not the groups
themselves. Additionally, the Cambrian animals do not "appear fully formed";
there are possible precursors in earlier rocks, rare but not nonexistent.
If you want to see what we looked like back in the Cambrian, click here:
http://www.nmnh.si.edu/paleo/shale/pwiwax.htm
That spiny-looking, slug-like animal was the only chordate in existence back
then. It was probably our great-great-great-great... etc. ancestor -- yours,
mine, every cat and dog, every bird and fish, every vertebrate on this planet --
probably descended from something just like that.
> HOMOLOGY. Why do textbooks define homology as similarity due
> to common ancestry, then claim that it is evidence for
> common ancestry -- a circular argument masquerading as
> scientific evidence?
This is a loaded question -- it assumes the answer to another question that has
not been asked, namely, "Do textbooks define homology as similarity due to
common ancestry, then claim that it is evidence for common ancestry?" The answer
is no, they do not. A simple, non-circular definition for homology is as
follows: a detailed similarity of organization that is functionally unnecessary.
For example, mammals as drastically dissimilar as humans, whales and bats have
fundamentally similar bone structure in their upper limbs, though adapted to
serve different purposes in each. In each species, our upper limbs terminate in
five bones. In humans, those bones of course are the fingers; but bats have the
same five bones, greatly elongated to become the structure of their wings; and
whales again have the same five "finger" bones, though buried within their fins.
This is exactly what we would expect from common descent -- the same basic
structure in an ancestral species, altered to serve varying functions in its
descendants; after all, evolution builds on what exists rather than inventing
new adaptations from scratch -- and therefore it is solid evidence for common
descent having taken place.
> VERTEBRATE EMBRYOS. Why do textbooks use drawings of
> similarities in vertebrate embryos as evidence for their
> common ancestry -- even though biologists have known for
> over a century that vertebrate embryos are not most similar
> in their early stages, and the drawings are faked?
Actually, while Haeckel did exaggerate his drawings in such a way as to make
them fraudulent (which is why they are *not*, and should not be, used in modern
textbooks as evidence for evolution), he did not invent the similarities
entirely. All vertebrate embryos do develop from similar initial body plans; the
same basic structures in embryos turn into different things in the adult
animals, which is of course exactly what we would expect if later, more derived
species had evolved from earlier ones.
> ARCHAEOPTERYX. Why do textbooks portray this fossil as the
> missing link between dinosaurs and modern birds -- even
> though modern birds are probably not descended from it, and
> its supposed ancestors do not appear until millions of years
> after it?
Obviously Archaeopteryx's ancestors, real or supposed, by definition must appear
before it.
That being said, paleontologists do not believe that Archae was the *direct*
ancestor of modern birds, but rather a side branch that died out. (To put it
another way, it wasn't the birds' parent; it was their uncle.) In either event,
it is still undeniable, extraordinary evidence of the link between birds and
dinos. Creationists do their best to raise a smoke screen, but how can even they
deny the evidence of what is undeniably a small, predatory theropod dinosaur --
with perfect avian feathers?
> PEPPERED MOTHS. Why do textbooks use pictures of peppered
> moths camouflaged on tree trunks as evidence for natural
> selection -- when biologists have known since the 1980s that
> the moths don't normally rest on tree trunks, and all the
> pictures have been staged?
The reason that pictures of peppered moths resting on tree trunks are staged for
the textbooks is that animals tend to be notoriously poor photography subjects,
and often do inconvenient things like fly away when you want to take their
picture. Nevertheless, peppered moths *do* normally rest on tree trunks; the
staged pictures are just a reproduction of what really does happen in the wild.
Wells' claim to the contrary is flat-out false.
> DARWIN'S FINCHES. Why do textbooks claim that beak changes
> in Galapagos finches during a severe drought can explain the
> origin of species by natural selection -- even though the
> changes were reversed after the drought ended, and no net
> evolution occurred?
Because droughts and wet seasons are just simple, short-term yearly cycles.
Evolution works on a longer scale than that, and long-term climatic variations
drive large-scale evolution. In any event, what the observed evolution of the
finches' beaks demonstrate is that natural selection is capable of rapidly
producing new variety to deal with environmental factors. Not much net evolution
occurs now because each species of finch is now adapted to its own niche -- but
if a *single*, unspecialized finch had arrived on the islands millions of years
ago, it would have radiated into numerous subpopulations each with adaptations
for a specialized way of living. That's what the finch experiments demonstrate.
> MUTANT FRUIT FLIES. Why do textbooks use fruit flies with an
> extra pair of wings as evidence that DNA mutations can
> supply raw materials for evolution -- even though the extra
> wings have no muscles and these disabled mutants cannot
> survive outside the laboratory?
I've never heard of experiments producing crippled four-winged fruit flies, but
it wouldn't surprise me -- other experiments have produced monsters like flies
with legs for antennae. Wells probably devotes his time to dealing with these
poor cripples because he doesn't want to deal with the *real* molecular evidence
for evolution -- mutations duplicating and changing existing genes, producing
new adaptations, new information and new functions, increasing fitness and
producing novel means of survival. We've observed everything from bacteria
gaining resistance to antibiotics (which they do through a multitude of methods,
from inventing new enzymes to break the drugs down to literally pumping them out
of their cells) to humans with mutations that make them resistant to injury and
disease (one well-studied mutation, possessed by an Italian family, grants
almost total immunity to atherosclerosis and heart disease; another one gives
its possessors super-dense bones which are almost impossible to break).
> HUMAN ORIGINS. Why are artists' drawings of ape-like humans
> used to justify materialistic claims that we are just
> animals and our existence is a mere accident
Wells apparently can't keep his metaphysics separate from his science. If he
doesn't like evolution because he thinks it's purposeless, that's his decision,
but a) it's only his opinion, science itself says no such thing; and b) many
people disagree with him -- even Christian evolutionary biologists, who see
evolution as not only the true, but also the most fitting, method of creation of
a transcendent god.
> -- when fossil
> experts cannot even agree on who our supposed ancestors were
> or what they looked like?
I wonder what "fossil experts" he thinks he's referring to. The family tree of
humanity is widely agreed upon by paleoanthropologists, as well as the general
line of human descent. Now, maybe he thinks *creationists* are the "fossil
experts" -- but in that case let's see him explain this away:
http://talkorigins.org/faqs/homs/compare.html
While the creationists are adamant that none of these skulls are transitional,
but all are either fully human or fully ape, *they are not able to agree on
which is which* -- which is, of course, *exactly* what we would expect if these
were evolutionary transitions possessing the characteristics of both.
> EVOLUTION A FACT? Why are we told that Darwin's theory of
> evolution is a scientific fact -- even though many of its
> claims are based on misrepresentations of the facts?
Evolution *is* a scientific fact. It is Wells who consistently lies, deceives
and misrepresents in an attempt to cast doubt on one of the most strongly
supported and powerful theories science has ever produced; but when the
deceptions of creationist arguments are exposed and torn away, it is the theory
of evolution that emerges triumphant.
--
And I want to conquer the world,
give all the idiots a brand new religion,
put an end to poverty, uncleanliness and toil,
promote equality in all of my decisions...
--Bad Religion, "I Want to Conquer the World"
http://www.ebonmusings.org ICQ: 8777843
Cyde Weys
"Richard Clayton" <for...@earthlink.net> wrote in message
news:3D0B75A0...@earthlink.net...
> John Mott wrote:
> > :
> > : EVOLUTION A FACT? Why are we told that Darwin's theory of
> > : evolution is a scientific fact -- even though many of its
> > : claims are based on misrepresentations of the facts?
> >
> > unsubstantiated assertion
>
> You miss the point. Picture a student coming to class with these ten
> questions written down to ask his teacher. Imagine him raising his hand
> for permission to speak and then reading them off one at a time.
Unsubstantiated assertion.
> Yes, a high school science teacher could respond that each of them
> are mere "unsubstantiated assertions." Better still, the teacher could
> explain the logical and scientific fallacies in each one. ("It doesn't
> matter whether or not archaeopteryx was a DIRECT ancestor of modern
> birds. The tree of life has many branches, not all of which survive
> indefinitely. The important thing is that it's a true _transitional
> form_-- a bird lacking many typical bird features while also possessing
> numerous distinctly reptilian features.")
Unsubstantiated assertion.
> Now look at it from the point of view of the students. If the
> teacher merely dismisses the questions with a reply of "unsubstantiated
> assertion," the students will (correctly) interpret that as handwaving.
> On the other hand, if the teacher answers each question in careful
> detail, the kid with the question list can declare "Wow, evolutionists
> sure have to work HARD to answer these simple questions!" In short, this
> is the same kind of propaganda used by Gish, Hovind, and their ilk--
> they don't give a wet slap about science or honesty; they merely want to
> create enough verbal sleight-of-hand to make sure the flock stays
> fleeced.
Unsubstantiated assertion.
> IMHO, perhaps the best response of all for the hypothetical biology
> teacher would be to explain why each one of those is a very loaded
> question, if not completely dishonest-- similar to asking somebody "Are
> you STILL beating your wife?"
Unsubstantiated assertion.
Obviously nothing can be proven, and thus creationism is true, evolution is
false, night is day, and when it is day, the sky is green and the grass
blue.
R. Baldwin
"Adam Marczyk" <ebon...@hotmailNOTexcite.com> wrote in message
news:ugn3rfd...@corp.supernews.com...
Frank Steiger
for years. These claims have debunked over and over again. The questioner is
not looking for answers. He (or she) is pathetically trying to convince the
gullible that falsehood is truth. By the way, most or all of these points
are covered in my web site http://home.attbi.com/~fsteiger/creation.htm or
its links to other sites.
"Richard S. Norman" <rno...@umich.edu> wrote in message
news:rknmguc6krgvd687g...@4ax.com...
Herb Martin
news:WgQO8.525$ua4...@nwrddc03.gnilink.net...
> I'd like to nominate this.
> "Adam Marczyk" <ebon...@hotmailNOTexcite.com> wrote in message
I will second the nomination. Before seeing the
POMN suggestion I was about to compliment the
author separately.
Good job Adam.
[And good idea, R. Baldwin.]
--
Richard Clayton
::snort:: You're starting to sound like Philosopher7. (^_^)
--
Richard Clayton (for...@earthlink.net)
"The idea that nothing is provable is very attractive to people whose
ideas are contradicted by every shred of available evidence." -- Steven
J.
Joe T.
"Adam Marczyk" <ebon...@hotmailNOTexcite.com> wrote in message
>
<SNIP>
>We've observed everything from bacteria
> gaining resistance to antibiotics (which they do through a multitude of
methods,
> from inventing new enzymes to break the drugs down to literally pumping
them out
> of their cells) to humans with mutations that make them resistant to
injury and
> disease (one well-studied mutation, possessed by an Italian family, grants
> almost total immunity to atherosclerosis and heart disease; another one
gives
> its possessors super-dense bones which are almost impossible to break).
>
There is also a tribe in Africa that is completely immune to HIV due to a
mutation of a surface protein on their Helper T Lymphocytes.
Cyde Weys
> > Unsubstantiated assertion.
> >
> > Obviously nothing can be proven, and thus creationism is true, evolution
is
> > false, night is day, and when it is day, the sky is green and the grass
> > blue.
>
> ::snort:: You're starting to sound like Philosopher7. (^_^)
Unsubstantiated assertion!
(Of course, you saw this coming, didn't you?)
xyzzy
>I'm no expert on this but I'm curious ... I saw this post on
>another board and was wondering what the answers are:
>
>
>Ten Questions to Ask Your Biology Teacher about Evolution
One question to ask the student who brought this in:
"From which creationist pamphlet are you quoting this?"
I agree with some others who have responded: There's nothing
new with these question, they have been asked many times and
have been answered. I would give this as a homework assignment
to the class, maybe to do a little internet research if they
cannot already figure out the answers for themselves and let
them discuss what they find. Yes, it's silly propaganda, but
also a good opportunity to test whether the students are able
to recognize bamboozle when they see one.
Adam Marczyk
news:ugn3rfd...@corp.supernews.com...
[snip]
Doh - I need to correct myself here.
> > DARWIN'S TREE OF LIFE. Why don't textbooks discuss the
> > "Cambrian explosion," in which all major animal groups
> > appear together in the fossil record fully formed instead of
> > branching from a common ancestor -- thus contradicting the
> > evolutionary tree of life?
>
> "All major animal groups" is a flat-out lie. To name just one example, there
> were no vertebrates in the Cambrian -- that means no birds, no amphibians, no
> fish, no reptiles, and no mammals. There were potential *ancestors* of
> vertebrates -- quite bizarre wormlike animals with primitive spinal cords,
> nothing at all like what exists today -- but that's it. Similar statements
hold
> true for other major groups: their distant ancestors existed, but not the
groups
> themselves. Additionally, the Cambrian animals do not "appear fully formed";
> there are possible precursors in earlier rocks, rare but not nonexistent.
>
> If you want to see what we looked like back in the Cambrian, click here:
>
> http://www.nmnh.si.edu/paleo/shale/pwiwax.htm
>
> That spiny-looking, slug-like animal was the only chordate in existence back
> then. It was probably our great-great-great-great... etc. ancestor -- yours,
> mine, every cat and dog, every bird and fish, every vertebrate on this
planet --
> probably descended from something just like that.
I'm messing up my Cambrian species. Wiwaxia isn't the one that could be our
ancestor; it's thought to be a distant relative of the mollusks. The *real*
Cambrian chordate that could have given rise to the vertebrates is Pikaia, which
you can see here:
http://www.nmnh.si.edu/paleo/shale/ppikaia.htm
(Knew something looked funny when you clicked on that other link, didn't you?)
Thanks to Stewart Hinsley for pointing this out.
C. Thompson
>
> Don <dbi...@elkgrove.net> wrote in message news:3d0b...@207.173.96.5...
> > I'm no expert on this but I'm curious ... I saw this post on
> > another board and was wondering what the answers are:
>
> What other board? We'll go and set 'em straight. ;)
>
> > Ten Questions to Ask Your Biology Teacher about Evolution
>
> Ah, Jonathan Wells, is it? Well, he certainly is no problem to debunk. Here are
> the long answers to these questions:
>
>
> > HOMOLOGY. Why do textbooks define homology as similarity due
> > to common ancestry, then claim that it is evidence for
> > common ancestry -- a circular argument masquerading as
> > scientific evidence?
>
> This is a loaded question -- it assumes the answer to another question that has
> not been asked, namely, "Do textbooks define homology as similarity due to
> common ancestry, then claim that it is evidence for common ancestry?" The answer
> is no, they do not. A simple, non-circular definition for homology is as
> follows: a detailed similarity of organization that is functionally unnecessary.
> For example, mammals as drastically dissimilar as humans, whales and bats have
> fundamentally similar bone structure in their upper limbs, though adapted to
> serve different purposes in each. In each species, our upper limbs terminate in
> five bones. In humans, those bones of course are the fingers; but bats have the
> same five bones, greatly elongated to become the structure of their wings; and
> whales again have the same five "finger" bones, though buried within their fins.
> This is exactly what we would expect from common descent -- the same basic
> structure in an ancestral species, altered to serve varying functions in its
> descendants; after all, evolution builds on what exists rather than inventing
> new adaptations from scratch -- and therefore it is solid evidence for common
> descent having taken place.
>
(snip)
I was quite pleased to see this, as it annoys me to no end that so many
people associate homology with similarity. Similarity is the bane of
evolutionary biologists everywhere. Here David quite clearly makes the
point that similarity is not required; indeed, it can be completely
absent.
S.J. Gould makes this point indirectly in _The Panda's Thumb_. He
describes his surprise when he sees the Panda has an extra digit- 6 in
all. It turns out that the 'thumb' (which the animal uses to strip
leaves from bamboo) is an enlargement of the radial sesamoid bone in the
wrist. It is similar to a thumb but it is homologous to one of our
carpal bones. (You could say the panda's thumbs are analogous to our
thumbs- similar function using different structures).
Darwin went to great lengths to describe homology, except he didn't call
it that. His work on orchids is full of homology: the striking
adaptations of orchids are all based on structural alterations to petals
and sepals.
Finally, I am somewhat surprised that no one has mentioned embryonic
tissues. Of course the ultimate arbiter of homology is which genes are
being activated to produce the structure, but I am unaware that we have
this information for any complex structures. We do know, however, that
homologous structures arise from the same tissues (endoderm, ectoderm,
and mesoderm when present) in the same regions of the embryo. It is a
definitive disproof of homology if it can be shown that the structures
arise from different tissues, or even significantly different regions of
the embryo.
Chris
--
Remove the obvious spam-gagger when replying please.
C. Thompson
>
> Adam Marczyk <ebon...@hotmailNOTexcite.com> wrote in message
> news:ugn3rfd...@corp.supernews.com...
>
> [snip]
>
> Doh - I need to correct myself here.
>
DOH. I think I called you David in my earlier post. Sorry bout that.
John Harshman
Just not true. Homology is usually defined as similarity due to common
ancestry. The question is not whether homology is used as evidence for
common ancestry. Since it's defined that way -- homology, by definition,
results from common ancestry -- the question is whether particular
similarities are homologies. Evidence that they are homologies is by
definition evidence of common descent. And there are many forms of
evidence that similarities are homologous, most particularly their
hierarchical arrangement among organisms.
> I was quite pleased to see this, as it annoys me to no end that so many
> people associate homology with similarity. Similarity is the bane of
> evolutionary biologists everywhere. Here David quite clearly makes the
> point that similarity is not required; indeed, it can be completely
> absent.
I have to disagree. Similarity is a minimum criterion for suspecting
homology. That similarity may be subtle, but unless it's there we have
nothing. Not all similarity is homology, but all homology is similarity.
> S.J. Gould makes this point indirectly in _The Panda's Thumb_. He
> describes his surprise when he sees the Panda has an extra digit- 6 in
> all. It turns out that the 'thumb' (which the animal uses to strip
> leaves from bamboo) is an enlargement of the radial sesamoid bone in the
> wrist. It is similar to a thumb but it is homologous to one of our
> carpal bones. (You could say the panda's thumbs are analogous to our
> thumbs- similar function using different structures).
>
> Darwin went to great lengths to describe homology, except he didn't call
> it that. His work on orchids is full of homology: the striking
> adaptations of orchids are all based on structural alterations to petals
> and sepals.
>
> Finally, I am somewhat surprised that no one has mentioned embryonic
> tissues. Of course the ultimate arbiter of homology is which genes are
> being activated to produce the structure, but I am unaware that we have
> this information for any complex structures.
We do to some extent, especially in comparative studies of the various
homeobox genes.
> We do know, however, that
> homologous structures arise from the same tissues (endoderm, ectoderm,
> and mesoderm when present) in the same regions of the embryo.
This isn't always true.
> It is a
> definitive disproof of homology if it can be shown that the structures
> arise from different tissues, or even significantly different regions of
> the embryo.
No, it isn't. I wish I could summon a concrete example off the top of my
head, but I can't. This isn't quite one, but it's what I can think of: is
the mammalian jaw homologous to the shark jaw?
>
> Chris
> --
> Remove the obvious spam-gagger when replying please.
--
*Note the obvious spam-defeating modification
to my address if you reply by email.
Herb Martin
our
> ancestor; it's thought to be a distant relative of the mollusks. The
*real*
> Cambrian chordate that could have given rise to the vertebrates is Pikaia,
which
> you can see here:
>
> http://www.nmnh.si.edu/paleo/shale/ppikaia.htm
I really appreciate the great links.
The only exposure I had to the Burgess shale was
Gould's book. (Which one was that "This View of Life"?)
> (Knew something looked funny when you clicked on that other link, didn't
you?)
Yes, I didn't recognize her at first.
C. Thompson
Similarities can be homologous, but it is not required. The classic
examples all point up the differences in structures that are homologous:
toe and horse's hoof; bat wing and human hand; porpoise (the mammal)
flipper and bat wing; ostrich wing and penguin wing fer gosh sake.
Strustures are homologous DESPITE the existence or absence of
similarity.
>
> > I was quite pleased to see this, as it annoys me to no end that so many
> > people associate homology with similarity. Similarity is the bane of
> > evolutionary biologists everywhere. Here David quite clearly makes the
> > point that similarity is not required; indeed, it can be completely
> > absent.
>
> I have to disagree. Similarity is a minimum criterion for suspecting
> homology. That similarity may be subtle, but unless it's there we have
> nothing. Not all similarity is homology, but all homology is similarity.
I can agree with the first half of your paragraph. Indeed, similarities
are reason to suspect similarity. It is also reason to suspect
convergent evolution. Things can be homologous and not be similar, even
subtly so. Do you see a similarity between the middle toe of a
salamander and a horse's hoof? The only real similarity is the position
they occupy on the end of the animals' feet, yet they are homologous.
>
> > S.J. Gould makes this point indirectly in _The Panda's Thumb_. He
> > describes his surprise when he sees the Panda has an extra digit- 6 in
> > all. It turns out that the 'thumb' (which the animal uses to strip
> > leaves from bamboo) is an enlargement of the radial sesamoid bone in the
> > wrist. It is similar to a thumb but it is homologous to one of our
> > carpal bones. (You could say the panda's thumbs are analogous to our
> > thumbs- similar function using different structures).
> >
> > Darwin went to great lengths to describe homology, except he didn't call
> > it that. His work on orchids is full of homology: the striking
> > adaptations of orchids are all based on structural alterations to petals
> > and sepals.
> >
> > Finally, I am somewhat surprised that no one has mentioned embryonic
> > tissues. Of course the ultimate arbiter of homology is which genes are
> > being activated to produce the structure, but I am unaware that we have
> > this information for any complex structures.
>
> We do to some extent, especially in comparative studies of the various
> homeobox genes.
>
> > We do know, however, that
> > homologous structures arise from the same tissues (endoderm, ectoderm,
> > and mesoderm when present) in the same regions of the embryo.
>
> This isn't always true.
Ref. please?
>
> > It is a
> > definitive disproof of homology if it can be shown that the structures
> > arise from different tissues, or even significantly different regions of
> > the embryo.
>
> No, it isn't.
By whose definition please?
> I wish I could summon a concrete example off the top of my
> head, but I can't. This isn't quite one, but it's what I can think of: is
> the mammalian jaw homologous to the shark jaw?
Off the top of my head I am not sure. Is a shark's jaw descended from
primordial gill arches? My admittedly hazy memory tells me that they
are. I will have to do some checking. Why don't you just tell me what
you think about it, and the rationale?
Cyde Weys
"Frank Steiger" <fste...@attbi.com> wrote in message
news:GuQO8.57001$6m5....@rwcrnsc51.ops.asp.att.net...
> These are the same old tired propaganda claims that have been kicking
around
> for years. These claims have debunked over and over again. The questioner
is
> not looking for answers. He (or she) is pathetically trying to convince
the
> gullible that falsehood is truth. By the way, most or all of these points
> are covered in my web site http://home.attbi.com/~fsteiger/creation.htm
or
> its links to other sites.
Sorry bub, creationism is still wrong and evolution right.
Adam Marczyk
news:3D0D43...@hotmail.com...
> John Harshman wrote:
[snip]
> > > I was quite pleased to see this, as it annoys me to no end that so many
> > > people associate homology with similarity. Similarity is the bane of
> > > evolutionary biologists everywhere. Here David quite clearly makes the
> > > point that similarity is not required; indeed, it can be completely
> > > absent.
> >
> > I have to disagree. Similarity is a minimum criterion for suspecting
> > homology. That similarity may be subtle, but unless it's there we have
> > nothing. Not all similarity is homology, but all homology is similarity.
>
> I can agree with the first half of your paragraph. Indeed, similarities
> are reason to suspect similarity. It is also reason to suspect
> convergent evolution. Things can be homologous and not be similar, even
> subtly so. Do you see a similarity between the middle toe of a
> salamander and a horse's hoof? The only real similarity is the position
> they occupy on the end of the animals' feet, yet they are homologous.
I would say that "homology" becomes less of a meaningful term in species so
distantly related, and with so much divergence between them, as these. The
example of a shark's jaw being homologous to a human jaw is another instance of
that. Are they homologous? Well technically, yes, if you want to go all the way
back to the origins of the vertebrate body plan; but in practice they've
undergone so much subsequent divergence that there's not really any point in
speaking of them being homologous.
Lane Lewis
>
> IMHO, perhaps the best response of all for the hypothetical biology
> teacher would be to explain why each one of those is a very loaded
> question, if not completely dishonest-- similar to asking somebody "Are
> you STILL beating your wife?"
>
> ($0.02 deposited)
> --
> Richard Clayton (for...@earthlink.net)
Actually the teacher should explain how science works and one should do ones
homework before asking a lot of questions. The student then could go back
and substantiate the questions with evidence (if any). Unlike the original
poster who obviously did no homework at all.
Lane
John Wilkins
Depending on how it played out in the classroom (ie, if anyone else got
involved or interested) I'd get them to look up the originals of a half
dozen textbooks to see what they *really* said, and then look up Wells
and others' comments about them, and each report on a separate question
in class, with questions from the other students. Make it into an
educational experience...
--
John Wilkins
Occasionally entertaining but never educating others
Brian O'Neill
news:_bcP8.40115$uX3....@nwrddc01.gnilink.net...
> > These are the same old tired propaganda claims that have been kicking
> around
> > for years. These claims have debunked over and over again. The
questioner
> is
> > not looking for answers. He (or she) is pathetically trying to convince
> the
> > gullible that falsehood is truth. By the way, most or all of these
points
> > are covered in my web site http://home.attbi.com/~fsteiger/creation.htm
> or
> > its links to other sites.
> Sorry bub, creationism is still wrong and evolution right.
Er, that's what the website says...
--
TIME ELAPSED SINCE I QUIT SMOKING:
Two years, two months, one week, one day, 3 hours, 50 minutes and 46
seconds.
31966 cigarettes not smoked, saving $3,995.80.
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See my Sig File FAQ: http://pages.prodigy.net/briank.o/SigFAQ.htm
David Sienkiewicz
news:aejplu$dn...@baran22.ttnet.net.tr...
> "Cyde Weys" <vze2...@verizon.net> wrote in message
> news:_bcP8.40115$uX3....@nwrddc01.gnilink.net...
>
> > > These are the same old tired propaganda claims that have been kicking
> > around
> > > for years. These claims have debunked over and over again. The
> questioner
> > is
> > > not looking for answers. He (or she) is pathetically trying to
convince
> > the
> > > gullible that falsehood is truth. By the way, most or all of these
> points
> > > are covered in my web site
http://home.attbi.com/~fsteiger/creation.htm
> > or
> > > its links to other sites.
>
> > Sorry bub, creationism is still wrong and evolution right.
>
> Er, that's what the website says...
I get the impression that Cyde is sometimes a bit hasty with his responses.
Frank has been around for a while in talk.origins, Cyde. He hasn't posted
much in a while, but his site is worth a good long look.
C. Thompson
Wow. You folks sure have a lot of extra time in your classrooms. I'm
envious.
Chris Thompson
True. There are, however, other cases. Anglerfish are a good example.
What similarity is there between the lure of an anglerfish and a fin ray?
Certainly there is similarity at the molecular level (there is in the
horse/salamander example mentioned above too) but very little morphological
similarity is evident.
Chris
John Harshman
<ebon...@hotmailNOTexcite.com> wrote:
I disagree. There's a quite practical reason, in that the jaw is one of
the major characters uniting gnathostomes.
John Harshman
> John Harshman wrote:
> >
> > In article <3D0CF8...@hotmail.com>, rockw...@REMOVEhotmail.com wrote:
> > Just not true. Homology is usually defined as similarity due to common
> > ancestry. The question is not whether homology is used as evidence for
> > common ancestry. Since it's defined that way -- homology, by definition,
> > results from common ancestry -- the question is whether particular
> > similarities are homologies. Evidence that they are homologies is by
> > definition evidence of common descent. And there are many forms of
> > evidence that similarities are homologous, most particularly their
> > hierarchical arrangement among organisms.
>
> Similarities can be homologous, but it is not required. The classic
> examples all point up the differences in structures that are homologous:
> toe and horse's hoof; bat wing and human hand; porpoise (the mammal)
> flipper and bat wing; ostrich wing and penguin wing fer gosh sake.
>
> Strustures are homologous DESPITE the existence or absence of
> similarity.
Sorry, but that makes absolutely no sense to me.
> > > I was quite pleased to see this, as it annoys me to no end that so many
> > > people associate homology with similarity. Similarity is the bane of
> > > evolutionary biologists everywhere. Here David quite clearly makes the
> > > point that similarity is not required; indeed, it can be completely
> > > absent.
> >
> > I have to disagree. Similarity is a minimum criterion for suspecting
> > homology. That similarity may be subtle, but unless it's there we have
> > nothing. Not all similarity is homology, but all homology is similarity.
>
> I can agree with the first half of your paragraph. Indeed, similarities
> are reason to suspect similarity.
Did you mean "...to suspect homology." there? Otherwise I don't get your
meaning.
> It is also reason to suspect
> convergent evolution.
It can indeed be difficult to tell the difference. Our main tool for doing
so is by comparing distribution of the character in question to the
distribution of other characters.
> Things can be homologous and not be similar, even
> subtly so.
Do you have a real example of this? (Because the one you give below just
isn't.) How would we recognize homology in the absence of similarity?
> Do you see a similarity between the middle toe of a
> salamander and a horse's hoof? The only real similarity is the position
> they occupy on the end of the animals' feet, yet they are homologous.
In fact there is a considerable, detailed similarity, much of which can
only be seen during development. I repeat: without similarity, there is no
homology. In the usage common among systematists, homology=synapomorphy.
> > > S.J. Gould makes this point indirectly in _The Panda's Thumb_. He
> > > describes his surprise when he sees the Panda has an extra digit- 6 in
> > > all. It turns out that the 'thumb' (which the animal uses to strip
> > > leaves from bamboo) is an enlargement of the radial sesamoid bone in the
> > > wrist. It is similar to a thumb but it is homologous to one of our
> > > carpal bones. (You could say the panda's thumbs are analogous to our
> > > thumbs- similar function using different structures).
> > >
> > > Darwin went to great lengths to describe homology, except he didn't call
> > > it that. His work on orchids is full of homology: the striking
> > > adaptations of orchids are all based on structural alterations to petals
> > > and sepals.
> > >
> > > Finally, I am somewhat surprised that no one has mentioned embryonic
> > > tissues. Of course the ultimate arbiter of homology is which genes are
> > > being activated to produce the structure, but I am unaware that we have
> > > this information for any complex structures.
> >
> > We do to some extent, especially in comparative studies of the various
> > homeobox genes.
> >
> > > We do know, however, that
> > > homologous structures arise from the same tissues (endoderm, ectoderm,
> > > and mesoderm when present) in the same regions of the embryo.
> >
> > This isn't always true.
>
> Ref. please?
I was hoping that someone with a fresher memory of vertebrate embryology
could remind me of such a case.
> > > It is a
> > > definitive disproof of homology if it can be shown that the structures
> > > arise from different tissues, or even significantly different regions of
> > > the embryo.
> >
> > No, it isn't.
>
> By whose definition please?
By the one in common use everywhere in evolutionary biology, to my
knowledge: similarity resulting from common descent. If the tissue source
of a structure changes during evolution while the structure itself is
maintained, homology is maintained too.
> > I wish I could summon a concrete example off the top of my
> > head, but I can't. This isn't quite one, but it's what I can think of: is
> > the mammalian jaw homologous to the shark jaw?
>
> Off the top of my head I am not sure. Is a shark's jaw descended from
> primordial gill arches? My admittedly hazy memory tells me that they
> are. I will have to do some checking. Why don't you just tell me what
> you think about it, and the rationale?
You seem to have erased the part where I explained. The jaws of all
gnathostomes are descended from the same structure. Whether it's a gill
arch is unclear, but shark jaws have two forward elements, palatoquadrate
and mandibular, that are homologous to the quadrate and articular bones in
the jaws of most vertebrates. Over the course of evolution the
contributions to the jaw of these two elements have lessened, from being
the whole front part in primitive gnathostomes to being merely the
articulations in most vertebrates. The rest of the jaw has gradually been
replaced by recruitment of various dermal bones. In mammals this reaches
the extreme, as the quadrate and articular are excluded from the jaw
entirely, and become two bones of the inner ear, malleus and incus. The
mammalian jaw is composed entirely of dermal bones. Different tissue
source, same jaw. Homologous, but from different tissues.
Stephen Poley
<He...@LearnQuick.Com> wrote:
>> I'm messing up my Cambrian species. Wiwaxia isn't the one that could be
>our
>> ancestor; it's thought to be a distant relative of the mollusks. The
>*real*
>> Cambrian chordate that could have given rise to the vertebrates is Pikaia,
>which
>> you can see here:
>>
>> http://www.nmnh.si.edu/paleo/shale/ppikaia.htm
>
>I really appreciate the great links.
>
>The only exposure I had to the Burgess shale was
>Gould's book. (Which one was that "This View of Life"?)
Wonderful Life.
Stephen Poley
Barendrecht, Holland
Chris Thompson
news:harshman.diespamdi...@user-2ivfl90.dialup.mindspring.com
...
> In article <3D0D43...@hotmail.com>, rockw...@REMOVEhotmail.com
wrote:
>
> > John Harshman wrote:
> > >
> > > In article <3D0CF8...@hotmail.com>, rockw...@REMOVEhotmail.com
wrote:
>
> > > Just not true. Homology is usually defined as similarity due to common
> > > ancestry. The question is not whether homology is used as evidence for
> > > common ancestry. Since it's defined that way -- homology, by
definition,
> > > results from common ancestry -- the question is whether particular
> > > similarities are homologies. Evidence that they are homologies is by
> > > definition evidence of common descent. And there are many forms of
> > > evidence that similarities are homologous, most particularly their
> > > hierarchical arrangement among organisms.
> >
> > Similarities can be homologous, but it is not required. The classic
> > examples all point up the differences in structures that are homologous:
> > toe and horse's hoof; bat wing and human hand; porpoise (the mammal)
> > flipper and bat wing; ostrich wing and penguin wing fer gosh sake.
> >
> > Strustures are homologous DESPITE the existence or absence of
> > similarity.
>
> Sorry, but that makes absolutely no sense to me.
Sorry if I was not clear. See below.
> > > > I was quite pleased to see this, as it annoys me to no end that so
many
> > > > people associate homology with similarity. Similarity is the bane
of
> > > > evolutionary biologists everywhere. Here David quite clearly makes
the
> > > > point that similarity is not required; indeed, it can be completely
> > > > absent.
> > >
> > > I have to disagree. Similarity is a minimum criterion for suspecting
> > > homology. That similarity may be subtle, but unless it's there we have
> > > nothing. Not all similarity is homology, but all homology is
similarity.
> >
> > I can agree with the first half of your paragraph. Indeed, similarities
> > are reason to suspect similarity.
>
> Did you mean "...to suspect homology." there? Otherwise I don't get your
> meaning.
Yes, my mistake.
>
> > It is also reason to suspect
> > convergent evolution.
>
> It can indeed be difficult to tell the difference. Our main tool for doing
> so is by comparing distribution of the character in question to the
> distribution of other characters.
Yes, absolutely. My point is that similarity can be due to common descent,
or it can be due to convergence. Thus, similarity is not restricted to
homology. If however, structures are present due to common descent, they
will arise from the same embryonic origins; the odds of it evolving twice
from identical origins by happenstance are, I think, accepted to be quite
low. And development it seems provides stronger evidence of common descent
(or against common descent) than the deistribution of characters across
taxa.
>
> > Things can be homologous and not be similar, even
> > subtly so.
>
> Do you have a real example of this? (Because the one you give below just
> isn't.) How would we recognize homology in the absence of similarity?
In a different post, I mentioned the different appearances of a fin ray in
some fish, and the lure of an anglerfish.
>
> > Do you see a similarity between the middle toe of a
> > salamander and a horse's hoof? The only real similarity is the position
> > they occupy on the end of the animals' feet, yet they are homologous.
>
> In fact there is a considerable, detailed similarity, much of which can
> only be seen during development. I repeat: without similarity, there is no
> homology. In the usage common among systematists, homology=synapomorphy.
I think I see the misunderstanding here. I am talking about similarity in
the end product. Certainly when you include embryonic similarities it is a
different matter. That is what I was driving at when I mentioned embronic
tissues.
>
> > > > S.J. Gould makes this point indirectly in _The Panda's Thumb_. He
> > > > describes his surprise when he sees the Panda has an extra digit- 6
in
> > > > all. It turns out that the 'thumb' (which the animal uses to strip
> > > > leaves from bamboo) is an enlargement of the radial sesamoid bone in
the
> > > > wrist. It is similar to a thumb but it is homologous to one of our
> > > > carpal bones. (You could say the panda's thumbs are analogous to
our
> > > > thumbs- similar function using different structures).
> > > >
> > > > Darwin went to great lengths to describe homology, except he didn't
call
> > > > it that. His work on orchids is full of homology: the striking
> > > > adaptations of orchids are all based on structural alterations to
petals
> > > > and sepals.
> > > >
> > > > Finally, I am somewhat surprised that no one has mentioned embryonic
> > > > tissues. Of course the ultimate arbiter of homology is which genes
are
> > > > being activated to produce the structure, but I am unaware that we
have
> > > > this information for any complex structures.
> > >
> > > We do to some extent, especially in comparative studies of the various
> > > homeobox genes.
Visit the URL I provide.
> > >
> > > > We do know, however, that
> > > > homologous structures arise from the same tissues (endoderm,
ectoderm,
> > > > and mesoderm when present) in the same regions of the embryo.
> > >
> > > This isn't always true.
> >
> > Ref. please?
>
> I was hoping that someone with a fresher memory of vertebrate embryology
> could remind me of such a case.
>
> > > > It is a
> > > > definitive disproof of homology if it can be shown that the
structures
> > > > arise from different tissues, or even significantly different
regions of
> > > > the embryo.
> > >
> > > No, it isn't.
> >
> > By whose definition please?
>
> By the one in common use everywhere in evolutionary biology, to my
> knowledge: similarity resulting from common descent. If the tissue source
> of a structure changes during evolution while the structure itself is
> maintained, homology is maintained too.
I understand that you mentioned above that you cannot offhand recall a case
where 2 species show a structure that is homologous despite arising from
differing embryonic tissues. Can you supply an example of a structure whose
embryonic source changed, despite the continued existence of the structure?
>
> > > I wish I could summon a concrete example off the top of my
> > > head, but I can't. This isn't quite one, but it's what I can think of:
is
> > > the mammalian jaw homologous to the shark jaw?
> >
> > Off the top of my head I am not sure. Is a shark's jaw descended from
> > primordial gill arches? My admittedly hazy memory tells me that they
> > are. I will have to do some checking. Why don't you just tell me what
> > you think about it, and the rationale?
>
> You seem to have erased the part where I explained.
Um, no offense, but there was no explanation in the original.
> The jaws of all
> gnathostomes are descended from the same structure.
Then they are homologous.
> Whether it's a gill
> arch is unclear, but shark jaws have two forward elements, palatoquadrate
> and mandibular, that are homologous to the quadrate and articular bones in
> the jaws of most vertebrates. Over the course of evolution the
> contributions to the jaw of these two elements have lessened, from being
> the whole front part in primitive gnathostomes to being merely the
> articulations in most vertebrates. The rest of the jaw has gradually been
> replaced by recruitment of various dermal bones. In mammals this reaches
> the extreme, as the quadrate and articular are excluded from the jaw
> entirely, and become two bones of the inner ear, malleus and incus. The
> mammalian jaw is composed entirely of dermal bones. Different tissue
> source, same jaw. Homologous, but from different tissues.
>
Well, not exactly. While reading up on this matter, I found what I thought
was an excellent source. It seems to be a transcription of a lecture from a
course titled Evolution and Development at U. of Oregon, and it addresses
precisely this issue.
First, let me make absolutely clear that they make no bones (hehe) about
similarity being a component of homology. Indeed, the lecturer (whom I
believe is one Craig Miller, a guest lecturer in a course taught by Charles
Kimmel, and if you're reading this, Wilkins, Prof. Kimmel plays the banjo)
says there are 4 components of homology: structure (similarity), topography,
connectivity, and development. He makes his points using the skull of an
adult bowfin and a stained zebrafish embryo- a very nice staining job, too
(the bowfin is not pictured).
First off, the URL is:
http://biology.uoregon.edu/classes/Bi355f99/lectures/lecture21.html
Here are some quotes that bear on this problem:
"In all gnathostomes, the jaw forms embryonically as hinged (jointed) dorsal
and ventral cartilage elements in the first (mandibular) arch. The second
(hyoid) arch is also jointed and the dorsal and ventral elements serve to
support the jaw."
"Remember, Chuck gave you four criteria upon which to judge homology
(structure, topography, connectivity, and development). This simple
cartilage stain establishes the first two; the back gill arch cartilages are
very similar in structure (they're cartilage rods, a bit smaller than those
in the anterior arches, but still suspiciously similar) and topographically
very similar to the first and second arch cartilages."
"Morphological evidence can be a very convincing basis upon which to
establish homology, but hopefully Chuck's gotten it into your heads that
development is the most important criterion. A mountain of developmental
evidence also suggests that in gnathostomes, all arches are segmental
homologs. I told you about fate-mapping experiments in which people labeled
individual neural crest cells in an embryo and watched them over time to see
what they made. These and other experiments have conclusively established
that ALL of the pharyngeal arch cartilages derive from the cranial neural
crest."
In contrast, function is described as the "shakiest" form of evidence upon
which to rest a hypothesis of homology. This strikes to the heart of
convergence, and I would be surprised if there was any dispute about this.
But let's take it one step further. It is often said that "form follows
function". Darwin wrote about "descent with modification"- the structure
change! Simply, form is plastic, and if a structure is co-opted for a novel
function, in a mature organism its form can be quite different from what is
seen even in related groups. This does not mean the structures have lost
their status as homologs. As you (correctly) pointed out, there is still
similarity at the developmental level. And unbeknownst to me (although
well-known I am sure to many other readers of t.o., and you mention homeobox
genes above) homology at the gene level can be mapped: see the stained
zebrafish larva at the abovementioned URL: areas of differing gene stain
different colors (quite neat, actually).
So we know that structures can change, and take on novel appearances. They
can be similar due to convergence or common descent. If we have similar
structures, how can we discern homology? As you point out, we can look at
related taxa for some corroboration. However, as Miller points out, the
definitive evidence is developmental. The fate-mapping data he mentions are
a good example. The same cells in embryos of different species give rise to
homologous structures.
I hope I expressed myself clearly here. I freely admit I am not an expert.
Chris
John Wilkins
> "John Harshman" <harshman....@sjm.infi.net> wrote in message
> news:harshman.diespamdi...@user-2ivfl90.dialup.mindspring.com
...
>
> First, let me make absolutely clear that they make no bones (hehe) about
> similarity being a component of homology. Indeed, the lecturer (whom I
> believe is one Craig Miller, a guest lecturer in a course taught by Charles
> Kimmel, and if you're reading this, Wilkins, Prof. Kimmel plays the banjo)
OK. Send him to Australia, and we'll record the MP3 for the Archive...
...
--
John Wilkins
Occasionally making sense
C. Thompson
Ahh, but the sound of that 5th string resounds across the continents....