tas8831
Well-Known Member
One of Darwin's arguments in favor of his theory was that of Vestigial Organs.
He wrote of such structures (he referred to them as 'rudimentary' in the 1st Edition):
And here, Darwin nearly predicts the subject of this thread's position (p. 416):
and later (p. 450-451):
But this is about Scadding, a relatively obscure zoologist, who penned an article in 1981 that creationists have been putting on a pedestal ever since.
Or, more accurately, they have been putting a quote, single sentence he wrote in that paper on a pedestal.
An example is here, from that great fibber for Jesus Dr. David Menton at 'Answers in Genesis':
The evolutionist S.R. Scadding, for example, has critically examined vestigial organs as evidence for evolution. He concluded: “Since it is not possible to unambiguously identify useless structures, and since the structure of the argument used is not scientifically valid, I conclude that ‘vestigial organs’ provide no special evidence for the theory of evolution.”
Funny that Menton - nor the hundreds or thousands of other creationists that glowingly paste that quote - thought anything odd about the phrase "special evidence."
As can be seen in Scadding's paper, he actually sees vestigials as good evidence for evolution, but only as homologous structures:
later:
Scadding's major problem, according to one critic, was his idiosyncratic definition of vestigial as being completely useless, and he sadly seemed to employ a common creationist "argument" indicating that a structure that can be claimed to do ANYTHING is thus not vestigial.
Scadding:
These are standard creationist claims.
Naylor, in response:
and more detail:
and so on.
Scadding did eventually respond (1982). He admitted what he had hinted at originally - that what most consider vestigial are actually just examples of homology, and that homology is good evidence for evolution:
Naylor states that ... "[vestigial organs] would still provide powerful evidence for the theory of evolution." I agree with this, but I suggest that this evidence is due to the homologies these organs illustrate and not to their vestigiality.
He stuck to his guns re: vestigiality, but it seems that only creationists care, and only creationists cite his paper as anything other than a short-lived curiosity.
The dishonesty comes from the creationist insistence that Scadding's position (SOLELY the part about vestigial organs not being evidence for evolution) is unassailable, correct, and proves that vestigial organs can be ignored - all the while ignoring in toto his argument that they are just homologous structures which in and of itself is good evidence for evolution.
ALWAYS be wary of creationists bearing quotes.
He wrote of such structures (he referred to them as 'rudimentary' in the 1st Edition):
"Rudimentary parts...are apt to be highly variable. We shall have to recur to the general subject of rudimentary and aborted organs... Thus rudimentary parts are left to the free play of the various laws of growth, to the effects of long-continued disuse, and to the tendency to reversion.
...A part developed in any species in an extraordinary degree or manner, in comparison with the same part in allied species, tends to be highly variable" p. 150-151
...A part developed in any species in an extraordinary degree or manner, in comparison with the same part in allied species, tends to be highly variable" p. 150-151
And here, Darwin nearly predicts the subject of this thread's position (p. 416):
"Again, no one will say that rudimentary or atrophied organs are of high physiological or vital importance; yet, undoubtedly, organs in this condition are often of high value in classification. No one will dispute that the rudimentary teeth in the upper jaws of young ruminants, and certain rudimentary bones of the leg, are highly serviceable in exhibiting the close affinity between Ruminants and Pachyderms. "
and later (p. 450-451):
"The meaning of rudimentary organs is often quite unmistakeable: for instance there are beetles of the same genus (and even of the same species) resembling each other most closely in all respects, one of which will have full-sized wings, and another mere rudiments of membrane; and here it is impossible to doubt, that the rudiments represent wings. Rudimentary organs sometimes retain their potentiality, and are merely not developed: this seems to be the case with the mammæ of male mammals...
An organ serving for two purposes, may become rudimentary or utterly aborted for one, even the more important purpose; and remain perfectly efficient for the other. "
An organ serving for two purposes, may become rudimentary or utterly aborted for one, even the more important purpose; and remain perfectly efficient for the other. "
But this is about Scadding, a relatively obscure zoologist, who penned an article in 1981 that creationists have been putting on a pedestal ever since.
Or, more accurately, they have been putting a quote, single sentence he wrote in that paper on a pedestal.
An example is here, from that great fibber for Jesus Dr. David Menton at 'Answers in Genesis':
The evolutionist S.R. Scadding, for example, has critically examined vestigial organs as evidence for evolution. He concluded: “Since it is not possible to unambiguously identify useless structures, and since the structure of the argument used is not scientifically valid, I conclude that ‘vestigial organs’ provide no special evidence for the theory of evolution.”
Funny that Menton - nor the hundreds or thousands of other creationists that glowingly paste that quote - thought anything odd about the phrase "special evidence."
As can be seen in Scadding's paper, he actually sees vestigials as good evidence for evolution, but only as homologous structures:
Vestigial organs represent simply a special case of homologous organs, i.e. structures similar i.n fundamental structure, position, and embryonic development,, but not necessarily in function. That al1 vertebrates, for example, are built along a common basic structural plan is obvious to any student of anatomy. While homologies between animal species suggest a common origin, the argument, given above asserts that vestigial organs provide special additional evidence for evolution. Our knowledge of anatomy, necessary to identify homologies, is based on straightforward observation of adult or embryonic structure. However, when one begins to investigate the function of these structures necessary to identify vestigiality, the situation is not so clear. In many cases the functions of minor structures are not well understood. Identification of function is often based on experimental procedures, the results of which require some interpretation....
later:
He described these as structures which are of no use to man but were of great, use to his ancestors and hence interprets these observations as supporting common descent. "In order to understand the existence of rudimentary organs, we have only to suppose that a former progenitor possessed the parts in question in a perfect state, and that under changed habits of life they became greatly reduced, either from simple disuse, or through the natural selection of those individuals which were least encumbered with a superfluous part ' aided by the other means previously indicated" (Darwin 1874, p. 24). Darwin never makes entirely clear why this particular class of homologous structures should provide such important support to his theory of descent with modification.
Scadding's major problem, according to one critic, was his idiosyncratic definition of vestigial as being completely useless, and he sadly seemed to employ a common creationist "argument" indicating that a structure that can be claimed to do ANYTHING is thus not vestigial.
Scadding:
I would suggest that the entire argument that vestigial organs provide evidence for evolution is invalid on two grounds, one practical, the other more theoretical. The practical problem is that of unambiguously identifying vestigial organs, i.e. those that have no function. The analysis of Wiedersheim's list of vestigial organs points out the difficulties. As our knowledge has increased the list of vestigial structures has decreased.... Anatomically, the appendix shows evidence of a lymphoid function since the submucosa is rnuch thickened and almost entirely occupied by lymphatic nodules and lyrnphocytes (Cray and Goss 1973, p. L242)....The coccyx serves as a point of insertion for several muscles and ligaments including the gluteus maximus (Gray and Goss 1973, p. 118).... I would conclude that in practice it is difficult if not impossible to unambiguously identify organs totally lacking in function.
These are standard creationist claims.
Naylor, in response:
ABSTRACT: Consideration of examples of vestigial organs and of the nature of scientific
statements (hypotheses) confirms the continued use of vestigial organs as evidence for the
theory of evolution. It is unreasonable to inf er any function for many vestigial
organs. whereas others possess altered or reduced functions. The claim that vestigial
organs cannot be used to support evolution is shown to be false.
statements (hypotheses) confirms the continued use of vestigial organs as evidence for the
theory of evolution. It is unreasonable to inf er any function for many vestigial
organs. whereas others possess altered or reduced functions. The claim that vestigial
organs cannot be used to support evolution is shown to be false.
and more detail:
That the paper by Scadding is seriously flawed is evident even on cursory reading. I shall,
however. rebut the arguments case by case in order to document the strength of the argument
from vestigial organs.
Scadding (p. 173) begins with the assumption that vestigial organs are necessarily non-functional and that they are, in any case, "simply a special case of homologous organs." As a vestigial organ is obviously the homolog of some non-vestigial organ in another. related organism, the second assumption contributes nothing one way or the other to the argument. The first assumption is potentially damaging, but is fallacious on two accounts: first, it is incorrect to state that to be vestigial an organ must be non-functional; and, secondly, there exist organs for which all available evidence suggests that they are truly non-functional....
In addition, there are organs for which all available evidence suggests that the only reasonable
hypothesis is that they lack functions. To argue that someone, somewhere. at some time
may suggest an imaginative function for such organs is to very seriously misunderstand the
structure of science (see also below). Science is concerned with possibilities and
probabilities for which evidence from the material world allows continued testing. Science
does not deal in absolute proof, but with statements that seem reasonable given the
available data (e.g., Popper, 1959)....
Even a cursory glance at the morphological and evolutionary literature shows a plethora of
vestigial and rudimentary structures overlooked by Scadding. Some of these are undoubtedly
functioning in reduced and/or altered manner; for others it is not reasonable to hypothesize any
sort of function. A summary of examples follows:
A Mammals:
1. Teeth in embryos of whale-bone whales (de Beer, 1958).
2. Milk teeth, with replacement buds, in young platypus (Anderson and Jonas, 1967).
3. Upper incisors, which never cut through the gums, in embryonic calves (Darwin in
Stauffer, 1975).
4. Egg tooth and caruncle in some marsupial embryos (Hill and de Beer, 1950).
5. Variable expression of canines in modern horses -- usually present in males and
usually lacking in females (Simpson, .1951).
6. Vestigial incisors in rats, mice, and rabbits (Mose-Salentjin, 1978).
7. Vestigial pelvic bones in whales (Grant, 1963).
8. Rudiment of Jacobson's organ in human embryos (de Beer, 1958).
9. Body hair in embryonic whales and humans (de Beer, 1958).
however. rebut the arguments case by case in order to document the strength of the argument
from vestigial organs.
Scadding (p. 173) begins with the assumption that vestigial organs are necessarily non-functional and that they are, in any case, "simply a special case of homologous organs." As a vestigial organ is obviously the homolog of some non-vestigial organ in another. related organism, the second assumption contributes nothing one way or the other to the argument. The first assumption is potentially damaging, but is fallacious on two accounts: first, it is incorrect to state that to be vestigial an organ must be non-functional; and, secondly, there exist organs for which all available evidence suggests that they are truly non-functional....
In addition, there are organs for which all available evidence suggests that the only reasonable
hypothesis is that they lack functions. To argue that someone, somewhere. at some time
may suggest an imaginative function for such organs is to very seriously misunderstand the
structure of science (see also below). Science is concerned with possibilities and
probabilities for which evidence from the material world allows continued testing. Science
does not deal in absolute proof, but with statements that seem reasonable given the
available data (e.g., Popper, 1959)....
Even a cursory glance at the morphological and evolutionary literature shows a plethora of
vestigial and rudimentary structures overlooked by Scadding. Some of these are undoubtedly
functioning in reduced and/or altered manner; for others it is not reasonable to hypothesize any
sort of function. A summary of examples follows:
A Mammals:
1. Teeth in embryos of whale-bone whales (de Beer, 1958).
2. Milk teeth, with replacement buds, in young platypus (Anderson and Jonas, 1967).
3. Upper incisors, which never cut through the gums, in embryonic calves (Darwin in
Stauffer, 1975).
4. Egg tooth and caruncle in some marsupial embryos (Hill and de Beer, 1950).
5. Variable expression of canines in modern horses -- usually present in males and
usually lacking in females (Simpson, .1951).
6. Vestigial incisors in rats, mice, and rabbits (Mose-Salentjin, 1978).
7. Vestigial pelvic bones in whales (Grant, 1963).
8. Rudiment of Jacobson's organ in human embryos (de Beer, 1958).
9. Body hair in embryonic whales and humans (de Beer, 1958).
and so on.
Scadding did eventually respond (1982). He admitted what he had hinted at originally - that what most consider vestigial are actually just examples of homology, and that homology is good evidence for evolution:
Naylor states that ... "[vestigial organs] would still provide powerful evidence for the theory of evolution." I agree with this, but I suggest that this evidence is due to the homologies these organs illustrate and not to their vestigiality.
He stuck to his guns re: vestigiality, but it seems that only creationists care, and only creationists cite his paper as anything other than a short-lived curiosity.
The dishonesty comes from the creationist insistence that Scadding's position (SOLELY the part about vestigial organs not being evidence for evolution) is unassailable, correct, and proves that vestigial organs can be ignored - all the while ignoring in toto his argument that they are just homologous structures which in and of itself is good evidence for evolution.
ALWAYS be wary of creationists bearing quotes.
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