(0) Before I begin my second reply, I would like to apologize to Mr. Troupe if he felt that I was talking down to him previously; that was not my intent - I was trying to add background and write broadly, with the general reader in mind; I was not directly replying to him. With that still the case, my second reply: (1) What is a species? Mr. Troupe takes issue with my discussion of what a genesis "kind" is and comments on the formation of new species:
"I am NOT saying that the formation of new species is permissible. I am saying that adaptation has not (ever) resulted in the formation of “new” species. For example, there may be many different types of birds, but they are still birds. Adaptation has never (and will never) change that. Neither has countless thousands of “scientifically” induced mutations upon fruit flies ever produced anything but more fruit flies."
I get the impression (I could be wrong) that when I talk about "new species", he assumes I mean drastic changes; something akin to a direct transition from a reptile to bird. I think it would be helpful to revisit the species concept for this discussion; a simple definition is that a species is "[a group of] related organisms capable of interbreeding". We should modify that to read 'capable of interbreeding to produce fertile offspring' since animals like horses and donkeys can interbreed, but the result, mules, are sterile. (As a quick aside, I find the concept of a sterile hybrid to not sit well with the notion of a kind; why should they be only imperfectly able to reproduce with one another? Shouldn't it be more of an all or nothing scenario? Its almost as if they're intermediate in kind to one another...) With this definition of a species now in place, I would like to introduce the concept of a "ring species". If we look at where a given species lives, we will find that it generally stays confined to an area (a range) where its needs are well satisfied (i.e. cacti in the desert, salt-water fish in the ocean, pandas in bamboo forests, etc.). Usually, ranges are more-or-less solid areas, but due to geographical constraints, the range of certain species may take the shape of a ring.
This has occurred in sea gulls in northern latitudes (see image on http://hometown.aol.com/darwinpage/zimmergulls.htm ). To summarize the image:
|northern Europe||northern Europe Herring gull|
|northern N. America||American herring gull|
|eastern Siberia||Vega herring gull|
|mid Siberia||Birula's gull|
|mid western Siberia||Heuglin's gull|
|western Siberia||Siberian lesser black-backed gull|
|northern Europe||Lesser black-backed gull|
Along the ring (i.e. from top to bottom of the list), adjoining varieties can successfully interbreed and there is a continuum of characteristics. However, in northern Europe something odd happens: "the Herring Gull and Lesser Black-backed Gull -- are so distinct that they can't mate with each other although they live side by side." How many species of gull are we describing? If all the gulls except for those in northern Europe were wiped out (i.e. by some natural catastrophe), how many would we be describing then? This is why I brought up the concept of genesis "kind"; If you say that "every winged fowl after his kind" in 1:21 refers to "birds" that is significantly different from saying it means "each bird species". If the former, you can have variation among birds and populations can break off, forming new bird species, but not changing from anything within 'bird kind'. Whereas if the latter, each species is fixed. To a certain extent, it could be that you want to support both at the same time which seems to me like wanting to have your cake and eat it too :) Of course, if you are a young earth creationist, then what I am saying might seem foolish; after all, variation, changes in geographical distribution, etc. often take quite a bit of time to accumulate. I look forward to seeing if Mr. Troupe considers the earth to be ~6K years old (as per Bishop Ussher's chronology; see http://www.lhup.edu/~dsimanek/ussher.htm ) or almost a million times that (see http://www.talkorigins.org/faqs/faq-age-of-earth.html ) or something else entirely. (2) Accidentally on purpose, or, Purposefully accidental A general feeling I got reading Mr. Troupe's reply was that random events weren't really all that random; for example:
"Sterile, sick, deformed and inferior fruit flies! These planned and deliberate mutations have never produced a “new” species."
"Every change (of the Smith name) that took place, was the result of an intelligent, well thought out plan! It was not an accident. It did not “just happen.” It took a considerable amount of conscious effort."
I'll start with the family name example. My intent there was not to make any profound comment about human evolution, but to give a hypothetical example of how changes can accumulate by descent with modification. I used an example of family names because it was *that* which I wanted to track and anyone reading it would be able to grasp the concept. Whereas yes, the individuals changing their names put some thought into what they were doing in the example, the events were independent and not part of some conscious effort to continually alter the family name. For the fruit flies, I find the concept of a 'planned mutation' somewhat amusing; it is as if to say that a lottery with a million people playing somehow plans who the winner will be among those playing (we're talking a fairly run lottery, mind you ;). Historically speaking, scientists who induced mutations in plants and animals had no control over what genes were being mutated. In the gull example I brought up previously, the variations that separate individual varieties are probably significantly more than the individual gene mutations that change eye color in fruit flies. In the case of mules vs. donkeys or horses, there's a chromosomal number mismatch (affecting numerous genes) that results in the hybrid sterility. We should expect then that if researchers were going to try to create new species in the lab (meaning non-interbreeding populations, not necessarily anything majorly different) it could occur quite by accident if there was a significant build up in mutations that prevented the lab population from breeding with the original population from which it arose, but in which the lab population could still breed amongst themselves. At least some of the examples on http://www.talkorigins.org/faqs/faq-speciation.html should qualify as speciation in a laboratory setting without the researchers having caused it in a way other than 'setting up the lottery'. (3) Analogous structures Mr. Troupe raises an interesting point when he says:
"The existence of creatures with different characteristics – or even with the same characteristics of other creatures of a different kind (or species), proves absolutely nothing except the fact that such creatures do exist. Bats are mammals. Birds are fowls. Like fowls, bats have wings, and they fly. A bird characteristic, but not a bird, and not related to a bird."
This is the sort of thing that confounded early attempts at classification; primarily because it is based on what things do rather than their underlying structure. For example, we can form a group of things which walk on four legs: i.e. cats and praying mantises, and those that walk with two: i.e. penguins and people. But I think we can see fairly quickly that these are somewhat artificial categories. The achievement that Linnean classification brought was that it arranged organisms in a "nested hierarchy [...] by diagnosable morphologic criteria" (see http://www.gcssepm.org/special/cuffey_03.htm ). In terms of flight, both insects and birds can fly, but the wings that allow them to do so are completely different in terms of morphology. Thus they are classified separately - the structures are 'analogous'. Similarly, wings occur in three distinct vertebrate groups; birds, bats and the extinct pterosaurs. In all three the forelimbs were used, however, close examination of the bones involved reveals some very distinct differences (see http://www.ucmp.berkeley.edu/vertebrates/flight/converge.html and the three links on the page) The origin of analogous structures should be something of a mystery if a competent creator is assumed; why should there be three different ways of doing the same thing (four if you count insects)? Surely one would be better than the others and thus would have been picked. For that matter, if feathers are so great for flight, why don't bats have them? Why do they use a method similar to the extinct pterosaurs? Why do some insects have four wings, but others only two? Its questions like this that raised nagging doubts a century and a half ago. The evolutionary solution was that pre-existing structures were modified to do the task. As a quick end note to this section, Mr. Troupe mentioned that:
"The oldest known fossil bat is a fully formed bat, virtually identical in appearance to the modern, living bats of today. The bat was not ever, and is not now, a creature in transition."
There have been some good reasons suggested why the predicted fossils have not yet been found (see http://www.ucmp.berkeley.edu/mammal/eutheria/chirofr.html - yet there are some tantalizing hints that its probably just a matter of time). Also, the claim of the first bat fossils being "virtually identical" refers to the ability to fly and ignores some anatomical differences: "The first known fossil bat [...] did still have a few "primitive" features, though (unfused & unkeeled sternum, several teeth that modern bats have lost, etc.)" as per http://www.talkorigins.org/faqs/faq-transitional/part2a.htm l (4) Embryology When I asked a question about how a creationist would answer an embryological question, Mr. Troupe replied:
"There is no explanation required! As stated before, whatever the embryo looks like during gestation proves nothing (and means nothing), except what is actually happening during gestation. If any part of a human embryo happens to look like a tadpole, or a sardine, or a part of something else, or even a similar looking part of the embryo of another creature, again, it does not mean, or prove anything."
While the concept of "ontogeny recapitulates phylogeny" as a scientific law was discarded (by the scientific community) at least a century ago, this does not mean that there's nothing to be learned from embryology. It should be remembered that embryological development is regulated by genes and that genes are inherited. Thus, if two organisms are closely related, we should expect their embryological development to be similar. I suggest a read-through of http://www.talkorigins.org/faqs/wells/haeckel.html and http://www.talkorigins.org/faqs/comdesc/section2.html#ontogeny (5) Definitions Mr. Troupe suggests that I am perhaps intentionally misunderstanding him regarding vestigial organs and repeated his statement that:
"under certain conditions the loss of organs (or their function) can occur. Examples of that are amphibians (or fish) isolated in dark caves, which have lost their capacity see, and in some cases with no eyes at all. But again, this merely demonstrates the concept of adaptation – not evolution. The loss of function of a structure (or even the structure itself) simply indicates the loss of genetic information from the gene pool, which is actually the reverse of what is required for evolution."
I think part of the problem is a definitional one regarding what "evolution" is (and why I wanted to define it early in my first reply). The popular view of evolution, that of progress and increasing complexity, is not consistent with the basic definition I gave (Darwin's, in fact) of "descent with modification". In such a case you can go either way. The most notable 'loss of information' evolution is that of parasites from free-living forms. Another good example would be of snakes evolving from reptiles with legs. Further, I don't think we're using the same definition of "vestigial organ". While Mr. Troupe states: "If these organs were truly vestigial, they would be totally useless.", that is not the meaning associated with it in biology; rather, only that its original function has become severely impaired or lost. Thus cave fish tend to have vestigial eyes which have become useless, while the human appendix no longer houses cellulose-digesting bacteria (see http://www.talkorigins.org/faqs/vestiges/appendix.html ) though if it has taken on a role in the immune system, that would be a gain in function unrelated to its original role. Mr. Troupe also challenges my assertion that the appendix is vestigial based on an analogy: "Some people have had one lung removed, also without ill effect (often, in fact BECAUSE of the ill effect it was causing them)." Yet I think that a distinction can be made; first, if you remove a single lung from a person, the individual will likely not be able to exercise as vigorously (a loss of ability). Second, if you remove *both* lungs, the person will die. This implies that lung tissue is vitally necessary for humans to live and that one's ability is proportional to the amount present. I cannot say the same for the appendix. Curiously, "In most snakes the right lungs is usually the largest and extends for over a 1/3 of the body. The left lung is then VERY small or absent. In effect, snakes only have one lung." (as per http://www.icon.co.za/~mvdmerwe/anatomy.htm#lungs ). Why a creator would have designed some snakes with a small chunk of a second lung escapes me. It seems to me far more elegant an explanation to say that snakes are derived from reptiles with two fully functional (but far shorter) lungs and that over time they evolved a solution to an increasingly long and narrow body. This would also be a 'loss of information' descent with modification, wouldn't it? (6) Archaeopteryx About our extinct feathered friend (I like Archaeopteryx, so I want to spend some more time talking about it ;), Mr. Troupe says:
"Most reputable scientists would say the same thing [as creationists]. Birds are not reptiles. [...] Archaeopteryx is classified as a bird, and is included with the birds. Possessing both avian and reptilian characteristics, this creature was very unusual indeed, but not the transitional form so desperately needed in order to validate the theory of evolution."
We must ask ourselves, what WOULD constitute a transitional fossil if not something like archaeopteryx? Similar to the fossil skull classification website I pointed out last time, it seems to me that to a certain extent, classifying Archaeopteryx as a bird is a choice like saying whether 1.5 should be rounded up to 2 or down to 1. If feathers are your diagnostic characteristic for birds, then Archaeopteryx MUST be a bird. However, it seems that certain bona fide dinosaurs also had feathers (see http://www.time.com/time/europe/photoessays/dino/01.html and http://www.peabody.yale.edu/exhibits/cfd/CFDintro.html ) while if you examine the legs and feet of birds you should notice scales: http://trc.ucdavis.edu/mjguinan/apc100/modules/Integument/hair/scales0/scales.html If you were going to, hypothetically, mind you, say that birds are heavily modified reptiles, what would the transitional critter between the two look like? Could there be a chain of several intermediates with increasingly bird-like characteristics? (i.e. gain of feathers in the first animal and then loss of teeth in the next?). If Archaeopteryx is a bona fide bird, then what would the hypothetical intermediate between it and a reptilian ancestor look like? Relatively shorter limbs and less feathers? Would that differ substantially from what they recently found in China? (7) Final thoughts I hope my writing and the examples that I have chosen have given at least some readers an insight into why scientists feel that evolution is good, epirical ('reliant on observation and experiment') science. If you want to learn more about evolution, please visit http://www.talkorigins.org (especially because my fingers are tired! ^_^;)
Go on to comments: By C. L. "Chuck"
Troupe - 16 Apr 2004
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