| Topic: |
Religions > Atheism |
| User: |
"david ford" |
| Date: |
01 Jan 2004 05:19:00 PM |
| Object: |
Similarities & Common Descent |
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
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| User: "Penny Nickels" |
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| Title: Re: Similarities & Common Descent |
03 Jan 2004 01:43:39 AM |
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"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
Penny writes:
Sounds like circular reasoning. But it doesn't alter the fact that
similarities are evidence for common ancestry.
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| User: "Randy Story" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 05:38:11 PM |
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"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
If two bridges have common structural similarities does that mean that they
have common anscentry or common design. I think common design.
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| User: "Denis Loubet" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 08:18:02 PM |
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"Randy Story" <rstorynw@olypen.com> wrote in message
news:vv9bult7875k39@corp.supernews.com...
"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
If two bridges have common structural similarities does that mean that
they
have common anscentry or common design. I think common design.
I would think the structural features of the bridge design were arrived at
by an evolutionary process that involved keeping those features that are
found to support bridges, and eliminating those features that did not.
In other words, trial and error.
--
Denis Loubet
dloubet@io.com
http://www.io.com/~dloubet
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| User: "robpar" |
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| Title: Re: Similarities & Common Descent |
02 Jan 2004 12:03:58 PM |
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On Thu, 1 Jan 2004 23:38:11 +0000 (UTC), "Randy Story"
<rstorynw@olypen.com> wrote:
"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
If two bridges have common structural similarities does that mean that they
have common anscentry or common design. I think common design.
How about there are limits on what will work, and what works is what
is used. In evolution only what works will continue by being passed
on. So common design is limited to what works, and for the most part
works well.
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| User: "Vic Sagerquist" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 06:06:56 PM |
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One day in alt.atheism, Also Sprach Randy Story:
"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
If two bridges have common structural similarities does that mean that
they have common anscentry or common design. I think common design.
Bridges are inanimate, dumbfuck.
--
Vic Sagerquist
aa#2011
______________
The fool says in his heart, "There is no God".
The wise man announces it to the world.
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| User: "mb" |
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| Title: Re: Similarities & Common Descent |
02 Jan 2004 06:09:52 AM |
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"Vic Sagerquist" <address@withheld.com> wrote in message
news:Xns9463A42CC2A8vicman@204.127.199.17...
One day in alt.atheism, Also Sprach Randy Story:
"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
If two bridges have common structural similarities does that mean that
they have common anscentry or common design. I think common design.
Bridges are inanimate, dumbfuck.
........OOOOOOOOOOOOOOOOOOOOOOSH ;-)
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| User: "Nathan Baum" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 07:33:24 PM |
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Randy Story wrote:
"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
If two bridges have common structural similarities does that mean that
they have common anscentry or common design. I think common design.
Bridges are not biological constructs. Significantly, bridges do not contain
any mechanism for self-replication.
A bridge is a phenotype of the genotype that is present within its human
designer(s). Evolution dictates common descent of genotypes, not
phenotypes. Most bridges are a modification of the design of previous
bridges, which is to say that modern bridge genotypes are evolved from old
bridge genotypes.
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| User: "Carl" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 06:12:16 PM |
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Randy Story wrote:
"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
If two bridges have common structural similarities does that mean that they
have common anscentry or common design. I think common design.
But what if bridges self replicated? This of course, does not negate
common design. However, the problem arises when common design is
required to explain subtle and usually predictable non-essential
variations of design. Common descent explains both.
--
Creation Science: the ***** child of Scientism and Fundamentalism.
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| User: "Roadrunner" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 09:39:27 PM |
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"Carl" <no_spam@all.fu> wrote in message news:3FF4B7C3.8030802@all.fu...
Randy Story wrote:
"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
If two bridges have common structural similarities does that mean that
they
have common anscentry or common design. I think common design.
But what if bridges self replicated? This of course, does not negate
common design. However, the problem arises when common design is
required to explain subtle and usually predictable non-essential
variations of design. Common descent explains both.
Bridges are not living material as we know it is it? Would bridges evolve
in better bridges without a creator changing it's design. Dont think so.
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| User: "Matt Silberstein" |
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| Title: Re: Similarities & Common Descent |
02 Jan 2004 12:31:40 PM |
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In talk.origins I read this message from "Roadrunner"
<pegasus@privat.utfors.se>:
"Carl" <no_spam@all.fu> wrote in message news:3FF4B7C3.8030802@all.fu...
Randy Story wrote:
"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
If two bridges have common structural similarities does that mean that
they
have common anscentry or common design. I think common design.
But what if bridges self replicated? This of course, does not negate
common design. However, the problem arises when common design is
required to explain subtle and usually predictable non-essential
variations of design. Common descent explains both.
Bridges are not living material as we know it is it? Would bridges evolve
in better bridges without a creator changing it's design.
Please tell me how to distinguish between bridges
self-replicating and bridges being alive?
Dont think so.
Then start thinking. If bridges self-replicated and, for example,
the longer bridges tended to survive to self-replicate, we would
tend to see longer bridges over time. If you disagree explain
why.
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| User: "Carl" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 11:47:06 PM |
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Roadrunner wrote:
"Carl" <no_spam@all.fu> wrote in message news:3FF4B7C3.8030802@all.fu...
Randy Story wrote:
"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
If two bridges have common structural similarities does that mean that
they
have common anscentry or common design. I think common design.
But what if bridges self replicated? This of course, does not negate
common design. However, the problem arises when common design is
required to explain subtle and usually predictable non-essential
variations of design. Common descent explains both.
Bridges are not living material as we know it is it? Would bridges evolve
in better bridges without a creator changing it's design. Dont think so.
I see you aren't familiar with genetic algorithms.
Here is a textbook, and damn it, it even has a bridge on the cover
http://www.wiley.com/WileyCDA/WileyTitle/productCd-0471999024.html
--
Creation Science: the ***** child of Scientism and Fundamentalism.
Scientism: science will provide the answer to everything
Fundamentalism: we already know the answer
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| User: "Lenny Flank" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 05:57:36 PM |
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Randy Story wrote:
"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
If two bridges have common structural similarities does that mean that they
have common anscentry or common design. I think common design.
Er, I've not noticed any bridges screwing and reproducing little bridges
as descendents. Have you?
<sigh> No WONDER everyone thinks creationists are idiots.
===============================================
Lenny Flank
"There are no loose threads in the web of life"
Creation "Science" Debunked:
http://www.geocities.com/lflank
DebunkCreation Email list:
http://www.groups.yahoo.com/group/DebunkCreation
-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----
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| User: "mb" |
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| Title: Re: Similarities & Common Descent |
02 Jan 2004 06:09:51 AM |
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"Lenny Flank" <lflank_nospam@ij.net> wrote in message
news:3ff4b448_4@corp.newsgroups.com...
Randy Story wrote:
"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
If two bridges have common structural similarities does that mean that
they
have common anscentry or common design. I think common design.
Er, I've not noticed any bridges screwing and reproducing little bridges
as descendents. Have you?
<sigh> No WONDER everyone thinks creationists are idiots.
WHOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO.......
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| User: "Dr. DuFonet" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 10:41:06 PM |
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"Lenny Flank" <lflank_nospam@ij.net> wrote in message
news:3ff4b448_4@corp.newsgroups.com...
Randy Story wrote:
"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
If two bridges have common structural similarities does that mean that
they
have common anscentry or common design. I think common design.
Er, I've not noticed any bridges screwing and reproducing little bridges
as descendents. Have you?
I have stopped eating brains as soon as the news came out.
--
Freedom of thought entails no "Intellectual Property".
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| User: "Boikat" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 05:45:26 PM |
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"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
It depends on how detailed you get with the "similar body structures". The
flipper of a sea turtle and the flipper of a blue whale are similar, yet the
two did not inherit the flipper from a common ancestor.
Boikat
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| User: "Roadrunner" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 09:42:44 PM |
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"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
Not necessarily wrong however the occuring can also be explained by a common
designer. That means you have to assume that the above is correct, you
can't state it being a fact though.
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| User: "Frank Reichenbacher" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 09:29:29 PM |
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"david ford" <dford3@gl.umbc.edu> wrote in message
news:b1c67abe.0401011520.5d1f4671@posting.google.com...
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
The spine of a euphorbia and the spine of a cactus are similar, yet science
believes the structures have quite different origins and do not indicate a
common ancestry.
The flipper of a whale and the hand of a human are dissimilar, yet they
share all the same bones and are derived from the same structures.
Frank
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| User: "Dave Oldridge" |
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| Title: Re: Similarities & Common Descent |
02 Jan 2004 10:05:04 AM |
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(david ford) wrote in
news:b1c67abe.0401011520.5d1f4671@posting.google.com:
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
It's entirely possible that the similarities in question are obtained by
separate means. For example the eyes of cephalopods are evolved from the
primitive eyes of molluscs like those of snails. The eyes of vertebrates
are evolved from the primitive eyes of very rudimentary chordates. Both
eyes have some very similar structures, including eyeballs, lenses,
retina, etc. But there are also differences that reveal their different
origins. For example, the cephalopod eye has the retina in front of the
optic nerves that connect it to the brain. The vertebrate eye has it
behind and has a blind spot where the nerve bundle goes through the
retina. Too see the blind spot, close your right eye. Hold your right
hand with the forefinger up and hold your left hand with the forefinger
up right next to it. Then, focusing with the open left eye on the right
forefinger, move the left hand off to the left. The finger will vanish.
--
Dave Oldridge
ICQ 1800667
Paradoxically, most real events are highly improbable.
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| User: "Woden" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 06:18:25 PM |
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(david ford) wrote in news:b1c67abe.0401011520.5d1f4671
@posting.google.com:
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
I guess that means that birds, insects, bats, and pterodactyls all had a
common ancestor with wings.
--
Woden
"religion is a socio-political institution for the control of
people's thoughts, lives, and actions; based on
ancient myths and superstitions perpetrated through
generations of subtle yet pervasive brainwashing."
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| User: "" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 09:10:03 PM |
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(david ford) wrote:
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
Well, taken out of context, I suppose what's wrong is that the claim
doesn't define similar body structures. What is the context of the
claim?
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| User: "Defininginfinite" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 09:39:02 PM |
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David writes;
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
For instance, the fact that most creatures' eyes, ears, noses and mouths are
all laid out the same. Is this from a common ancestor? No, it's the most
defensive way to have them. Species with their eyes under their mouths, simply
couldn't see well enough to survive... they kept getting food in their eyes:-o
Study hard,
Mark
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| User: "Matt Silberstein" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 06:23:05 PM |
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In talk.origins I read this message from
(david ford):
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
Two organisms are not sufficient, that is why scientists look at
thousands of organisms. "Similarities" is an insufficient
specification, what similarities are we talking about. Again, if
we had a dozen organisms we could begin to discuss a tree. Not
all similarities come from descent, we would want to look at more
details. Of course many of these problems would be resolved if
David did not play games like this and we saw the passage in the
original context. In that case I suspect that many of the issues
would be resolved.
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| User: "TomS" |
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| Title: Re: Similarities & Common Descent |
02 Jan 2004 07:48:39 AM |
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"On Fri, 2 Jan 2004 00:23:05 +0000 (UTC), in article
<uce9vvgfrod00r8vkvh23k8k4njdhroupv@4ax.com>, Matt Silberstein stated..."
In talk.origins I read this message from
(david ford):
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
Two organisms are not sufficient, that is why scientists look at
thousands of organisms. "Similarities" is an insufficient
specification, what similarities are we talking about. Again, if
we had a dozen organisms we could begin to discuss a tree. Not
all similarities come from descent, we would want to look at more
details. Of course many of these problems would be resolved if
David did not play games like this and we saw the passage in the
original context. In that case I suspect that many of the issues
would be resolved.
I have two comments.
First of all, Matt is pointing out something which I haven't noticed
in many of the other responses.
It is *not* enough to note similarity of structures between two
bodily forms.
What we have, in the world of life on earth, is a *nested
hierarchy* of structures. Which points to a "tree" of relationships.
This is what leads us to the idea of a "common ancestry" and
"descent with modification". But not merely this ...
Along with a *mechanism* for descent with modification, which is
non-directed ("random") variations and natural selection.
This combination is what made the Darwin-Wallace contribution
so significant in 19th century biology. People were quite familiar
with the similarity of structures among living things.
Some combination of:
* Nested hierarchy of features
* Non-directed variation in descent
* Selection
is also known in the study of languages (which leads to the hypothesis,
for example, of common ancestry of a great many languages known as
"Indo-European"), and the study of manuscript traditions (which leads
to various hypotheses about reconstructing original texts).
*On a related point* ...
I have this question for people who feel uncomfortable with the
idea of common ancestry, but would prefer "common design":
Why should I feel better about the idea that some "intelligent
designers", or whoever or whatever are responsible for my body's
form ...
Why should I feel better about the idea that they had a common
purpose in designing my body to be so very much like the body of
chimps and other apes?
Why should I feel better about that idea, than about the idea
that my body shares some physical common ancestry with that of chimps?
If the persons (or things) responsible for my body have made my
body with a similar purpose in mind, a similar purpose to the design
that they put into the bodies of chimps (and other apes, other
mammals, other vertebrates, and, indeed, all other living things) ...
What am I supposed to do with this information about the purposes
that they have built into my body? The aims of the design that they
had in mind when designing the human body-type? Does this tell me
that they intended me to behave like chimps and other apes? Does
this tell me that my body is made to act like a chimp's body? Am
I frustrating the goals of these designers, if I don't "act like an
ape"?
You see, I don't see myself as having any obligation to "act like
my ancestors". If my great-grandfather was a horse thief; or my
ancestors back, not too many generations, illiterate peasants who
never took a bath; or my more distant ancestors several centuries BC
were pagan tree-worhsippers or cannibals -- that doesn't tell me
anything at all about what my behavior should be like today. Likewise,
if my ancestors back a few million years ago were more like apes,
that doesn't bother me.
"Ancestry" does not obligate me, not in a way that "purposeful
design" might.
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| User: "MarkA" |
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| Title: Re: Similarities & Common Descent |
02 Jan 2004 06:58:52 AM |
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On Thu, 01 Jan 2004 23:19:00 +0000, david ford wrote:
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
Nothing wrong, as long as you don't try to apply it to people. When you
do that, you are going to inflame some people's "special act of creation"
reflex. Their entire worldview is absolutely dependant on the notion that
man is fundamentally different from other animals. If we "evolved" from
pre-human hominids, that distinction doesn't hold, and their theology
comes crashing down.
The obvious solution is to do what theists have ALWAYS done when the
physical evidence contradicts religious doctrine: persecute the scientist.
Fortunately for all of humankind (including, ironically enough, the
Creationists themselves), society has evolved to the point that theocrats
no longer have absolute authority over everyone's life (unless, of course,
you live in some of the few remaining theocracies, such as are found in
the Middle East). Therefore, they have to content themselves by trying to
rationalize how the evidence in favor of evolution *might be* false, and
further rationalize how weakening the theory of evolution indirectly
strengthens the "theory" that "Goddidit-all-by-magic", which is about as
antithetical to science as anything could possibly be.
--
MarkA
(still caught in the maze of twisty little passages, all different)
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| User: "Pip R. Lagenta" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 07:59:50 PM |
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On Thu, 1 Jan 2004 23:19:00 +0000 (UTC), (david
ford) wrote:
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
Spiders have eight legs and octopuses have eight legs, therefore
spiders and octopuses have a common ancestor that had eight legs?
Uhhh, no.
Define your terms clearly, and try again.
¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,
Pip R. Lagenta Pip R. Lagenta Pip R. Lagenta Pip R. Lagenta
ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø,¸¸,ø¤º°
-- Pip R. Lagenta
President for Life
International Organization Of People Named Pip R. Lagenta
(If your name is Pip R. Lagenta, ask about our dues!)
---
<http://home.comcast.net/~galentripp/pip.html>
(For Email: I'm at home, not work.)
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| User: "Steven Carr" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 06:33:21 PM |
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On Thu, 1 Jan 2004 23:19:00 +0000 (UTC), (david
ford) wrote:
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
I wonder if David has the same number of eyes and heads as his
siblings, and if this could be attributable to their having a common
ancestor?
Steven Carr
steven@bowness.demon.co.uk
http://www.bowness.demon.co.uk/
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| User: "gen2rev" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 06:01:26 PM |
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On Thu, 1 Jan 2004 23:19:00 +0000 (UTC), (david ford)
wrote in <b1c67abe.0401011520.5d1f4671@posting.google.com>:
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
Nothing that I can see. Of course, it all depends on what you mean by
"similar" Are bat wings and bird wings similar? They certainly have
similar functions, but no one is going to claim that their common
ancestor had wings.
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| User: "Penny Nickels" |
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| Title: Re: Similarities & Common Descent |
01 Jan 2004 11:50:26 PM |
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"gen2rev" <gen2rev@crosswinds.net> wrote in message
news:24d9vv4tmcg4nvv29mstrdbq7ajnla4bp4@4ax.com...
On Thu, 1 Jan 2004 23:19:00 +0000 (UTC), (david ford)
wrote in <b1c67abe.0401011520.5d1f4671@posting.google.com>:
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
gen2rev wrote:
Nothing that I can see. Of course, it all depends on what you mean by
"similar" Are bat wings and bird wings similar? They certainly have
similar functions, but no one is going to claim that their common
ancestor had wings.
Penny writes:
Since similar structure is evidence of common descent from a
common ancestor, one must conclude that the wings of a bat
a bird and the flying reptiles which share common aerodynamic
prosperities must have a common ancestor from which they
descended. A flying reptile, no doubt an ancestor of the pterosaur
must also be the ancestor of both bats and birds.
.
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| User: "Steven J." |
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| Title: Re: Similarities & Common Descent |
02 Jan 2004 12:29:22 AM |
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"Penny Nickels" <5cents@bellsouth.net> wrote in message
news:M96Jb.3894$wW5.1019@bignews6.bellsouth.net...
"gen2rev" <gen2rev@crosswinds.net> wrote in message
news:24d9vv4tmcg4nvv29mstrdbq7ajnla4bp4@4ax.com...
On Thu, 1 Jan 2004 23:19:00 +0000 (UTC), (david ford)
wrote in <b1c67abe.0401011520.5d1f4671@posting.google.com>:
What, if anything, is wrong with the following claim?:
If 2 organisms have similar body structures, then they obtained those
similar structures from a common ancestor-- the similarities in the
structures are attributable to common descent from a common ancestor
that had the original version of the structure(s) in question.
gen2rev wrote:
Nothing that I can see. Of course, it all depends on what you mean by
"similar" Are bat wings and bird wings similar? They certainly have
similar functions, but no one is going to claim that their common
ancestor had wings.
Penny writes:
Since similar structure is evidence of common descent from a
common ancestor, one must conclude that the wings of a bat
a bird and the flying reptiles which share common aerodynamic
prosperities must have a common ancestor from which they
descended. A flying reptile, no doubt an ancestor of the pterosaur
must also be the ancestor of both bats and birds.
No, *homology* (detailed similarity of structure not required for similarity
of function -- and whether the degree of similarity is "required" is
determined in large part by the study of disparity of structure among
organisms), when arranged in the nested hierarchy which is expected as a
result of common descent with modification (e.g. the nested hierarchy of
Indo-German languages) is evidence of common descent from a common ancestor.
Similarity of structure can be explained as convergence on a similar
solution to similar problems. There are numerous examples in nature.
The similarities of bat and bird (and pterosaur) wings are required for
flight. Actual homologies are closer between bats and a host of nonflying
mammals, while actual homologies are greater between birds and crocodilians
(or even birds and lizards and snakes) than between birds and mammals. This
is rather strong evidence (supplemented by the fossil record) that the last
common ancestor of birds and bats was flightless. So, for that matter, was
the more recent common ancestor of birds and pterosaurs, although both were
archosaurs.
-- Steven J.
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| User: "" |
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| Title: Re: Similarities & Common Descent |
02 Jan 2004 03:49:13 AM |
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"Penny Nickels" <5cents@bellsouth.net> wrote:
Since similar structure is evidence of common descent from a
common ancestor, one must conclude that the wings of a bat
a bird and the flying reptiles which share common aerodynamic
prosperities must have a common ancestor from which they
descended. A flying reptile, no doubt an ancestor of the pterosaur
must also be the ancestor of both bats and birds.
Hmmm... similar function but not similar structure. If you look at the
wings of bats and birds, you'll see that they're built quite differently
from each other. Forget the feathers and fur for a moment, and just look
at the bones.
.
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