Kudos to you, RDK, on the devil's advocate stuff. I was never very good at that myself. Anyway, here we go:
How do you know that the appendix is useless? Perhaps there's a use for it that we just don't know about yet. Declaring that the appendix has no advantageous effect on the human body whatsoever is arrogant and constitutes a science-stopper. Anybody familiar with the discovery of junk DNA knows the dangers of this.
The appendix isn’t useless. We now know that it has endocrine and lymphatic functions in the fetus and in developing children. It also functions as a lymphoid organ in adulthood with activity diminishing throughout life and disappearing past age 60.
http://www.scientificamerican.com/article.cfm?id=what-is-the-function-of-t
Regardless, it is probably a vestigial organ; it most likely had important functions in humans’ ancestors. This is evidenced by the fact that, though it has some endocrine and immune functions, there is no deficiency or problem in people who either have their appendix removed or are born without one (the body is clearly able to compensate for a missing appendix). Thus, whatever vital need it once fulfilled is now satisfied by other organs, even though the appendix itself is still present. Same with any other vestigial organ in other species.
Clearly, nobody’s stopping science!
Then you admit that the emergence of the lung in the case of the mudpuppy isn't a case of new information being created, and rather is an example of shuffling of already existing information?
And even if it is just a shuffling, it would not make any difference! Historically, some of the most notable evolutionary changes have been the result of reshuffling. Duplication of hox genes allowed for more complex morphology, such as that found in vertebrates and mammals. Duplications, translocations, and inversions were responsible for three color vision in humans and four color vision in most birds. A large portion of the human genome consists of transposable elements that have been moved around, altered, and duplicated.
The problem is that evolution purportedly doesn't work that way. You say structures like wings don't pop up in the course of one generation; it happens slowly across many many generations, as the advantageous trait is selected for again and again. The problem is that in the early stages of the wing's development, it would have little to no advantageous power whatsoever. Half a wing does absolutely nothing, and the idea that the precursor to feathers would provide enough advantage to be repeatedly selected for is simply absurd.
Ah, but this argument discounts traits that, while not necessarily advantageous, are not disadvantageous. Thus, there is no selective pressure either for or against them. Such a trait may be propagated, but not selected for. Eventually, you will end up with a bell shaped distribution. In the modern world, height would be a normally distributed trait. You’ll find some people who are very short, some people who are very tall, and a lot of people that lie on a continuum somewhere in the middle. Thanks to modern civilization and infrastructure, height is not actively selected for or against; it’s not as if the majority of short people die because they’re short, or as if tall people are able to survive on account of being tall. Thus, a bell shaped distribution is maintained. This is called variation. In fact, you see it every day in other forms as well. Black hair doesn’t, to anybody’s knowledge, provide any selective advantage over blonde hair, which doesn’t provide any selective advantage over brown or red hair. Then why have these varieties of hair emerged? Because they’re not selected
against. Maybe someday, if the environment were to change such that people with black hair were more likely to survive, then you’d see a shift towards darker hair colors.
Now let’s look at feathers. The first feather precursors and protofeathers started out as hair-like filaments or barbs. Since there was no selective pressure on them, they were neither removed from the gene pool nor actively promoted. Without selective pressure, there was a lot of room for variation. As one paper says:
“Once the minimal structural element, presumably recognizable as a barb, existed, a variety of phenotypes followed rapidly.” (
http://icb.oxfordjournals.org/cgi/content/full/40/4/631)
It is possible that there were some organisms without any protofeathers, some with a lot of protofeathers, and a lot in between. Evolution does not result in every structure having a purpose; as long as a structure or change is not selected against, it may remain in a population even without any apparent use. It is possible that protofeathers had no use and simply propagated the way I described above. Or, it is possible that they did provide some functional advantage over those without protofeathers, as this article says:
“They’re too thin and sparse to have aided in flight or heating, but their length and concentration around Beipiaosaurus’ head, neck and tail suggests a display function.
Feathers, it seems, started as evolutionary bling.”
(
http://www.wired.com/wiredscience/2009/01/dinofeathers/)
Just because we do not know exactly what function they had, does not mean they had no function. It is also to note what this paper says:
“Uncountable numbers of words have been written in attempts to combine structure and function in attempts to reconstruct the primitive feather and explain why feathers evolved; e.g., for flight, insulation, waterproofing, display, etc. (e.g., Feduccia, 1995Go). The arguments often overlook the fact that the entire range of phenotypic plasticity in feathers is generated from a single set of structural proteins, predicated on very few identifiable structural elements, and uniformly produced by a common mechanism. The differences in the morphogenesis of the various feather shapes are small and, to a large degree, correlate with differential growth and a high degree of repeated, but highly similar, events.”
(
http://icb.oxfordjournals.org/cgi/content/full/40/4/631)
It is important to remember that evolution never has an end in mind; protofeathers were not evolved for the purpose of eventually becoming feathers. They appeared by random chance, perhaps without function or perhaps with, and probably went in many different directions (most of which were not useful or selected for). One of those directions happened to be modern feathers. Changing or existing environmental conditions could have selected for those dinosaurs with bigger, “modern-feather-like” protofeathers. These may eventually have been selected for, for a number of reasons, such as the following:
“Some scientists speculate that feathers originated in dinosaurs to regulate body temperature. Just as in living birds, dinosaur feathers would have offered protection from cold and prevented overheating in the sun.”
(
http://nationalzoo.si.edu/Publications/ZooGoer/2005/3/birdevolution.cfm)
And what about the development of wings? There are a number of plausible and likely hypotheses for how wings came about, with a strong argument such as this one:
“After careful examination of the physical demands of pre-powered flight, we agree with Ostrom's (1974) arguments that Pro-avis developed the capabilities for powered flight from a bipedal cursorial habit. It is, however, difficult for us to envision how a structure such as an insect net could have developed lift, thrust, and drag capacities sophisticated enough for powered flight. We propose that a running and jumping bipedal animal that used its forelimbs for balance could be the precursor of animals with powered flight. The evolution of the modern avian wing is best explained as having passed through a series of adaptive stages concerned with the body orientation of a jumping insectivore. Extended forelimbs possessing minute increments of lift offer significant advantages to this jumping animal. Mass movements used for control of the body during a jump are very similar to the aerodynamic movements for control and propulsion used during powered flights. Thus, there is no need for the development of new and different neuromuscular pathways to perform powered flight as must be the case if an arboreal glider is to make the transition.”
(
http://www.jstor.org/pss/2460975)
Other similar studies have been performed that also come up with the most likely hypothesis:
http://biology.kenyon.edu/courses/biol241/bird flight TREE 1999 Hedenstrm_Anders.pdf
Even if we ignore all this, it has still been shown, by molecular genetics and developmental biology, that the wings of modern day birds came from dinosaur hands:
(
http://www3.interscience.wiley.com/journal/109741948/abstract?CRETRY=1&SRETRY=0)
(
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0003325)
Also an excellent read that answers a lot of questions, titled “What Good is Half a Wing?”:
http://www.uwgb.edu/dutchs/PSEUDOSC/HalfaWing.HTM
Funny; I thought natural selection is a mechanism of evolution, and that the two are completely different facets of evolutionary theory. Funny how evolutionists can't seem to agree on anything!
I have absolutely no idea what this means.
You seem to be implying that organisms can will themselves to evolve; almost as if they take an active part in their development. "...have sufficient reason to be on land in the first place"? Could you elaborate on this first?
And if said organisms are perfectly adapted to their marine habitat, what reason would they have to go on land in the first place?
Evolution is not a directed process. It does not “seek to perfect.” Evolution is an explanation for the mechanisms by which organisms become better adapted to environments and ecosystems, which may themselves be changing. Some organisms were clearly better served by mutations that, by chance, helped them survive on air above the water’s surface and eventually on land (which was a previously unfilled niche). Mutations that reduce competition with other organisms and improve survival are generally beneficial and consequently, they are selected for.
Then some might ask, “what about organisms like sharks that have stayed almost the same for hundreds of millions of years? Clearly, if they haven’t changed, it’s because they’re perfect for their environment. Then why did other marine organisms change?”
Sharks are, first of all, not “perfect” for their environment, they are “very well-suited” for their environment. A very important factor is geography. The fish that eventually evolved into land-dwellers and amphibians lived in shallows near land. Not all fish lived in these areas. Secondly, these fish were not “perfect for their environment”; rather, they were “very well suited for the niche they occupied in the ecosystem.” Some fishes, by random mutation, gained structures that gave them an advantage over other fishes in that ecosystem (because they were “very well suited,” not “perfect.” By definition, it would be impossible to improve on perfection). Some of these new structures gave the “improved” fish access to land; in other words, access to an unoccupied niche without competitors. It is no surprise that traits that would allow these new fish to occupy land were selected for.
The likelihood of having pre-existing attributes that allow them to begin the developmental process that takes them from the water to the land is miniscule.
Again, you're ignoring the biochemistry aspect of this. The first stages of the emergence of the "gas bladder" transitioning into the lung would have provided absolutely no selective advantage whatsoever, yet you expect us to believe that it was reproductively successful enough to be carried on through various generations, until it finally developed into a completely different organ?
This is why “pre-existing” attributes never evolve consciously in some sort of direction. It’s not as if the small sac of air was chosen by nature so that it could eventually form a lung. It was a random mutation that underwent either positive selective pressure (it was selected for) because it was useful or, as I explained above, was not under any selective pressure and thus, was neutral and became distributed throughout the population. It could very likely have started out neutral and, as its size increased in some fish, became beneficial and selected for.
Remember, “no selective advantage” doesn’t mean “selective disadvantage.” There is such a thing as neutrality. Remember my hair color example? Additionally, the first stages of the gas bladder may have had some function that we don’t know about. Or maybe it didn’t. But it propagated regardless, just like brunette hair. I don’t see any reason for all these different human hair colors either.
