Posted on 07/02/2005 7:47:33 PM PDT by DaveLoneRanger
I don't know why I bother, either. They have their minds made up, and no facts could ever change them.
Dead wrong. The body of scientific evidence backing evolution is immense.
1.Natural selection and variation has only and always been observed to be limited within the species level.
A total red herring, and also incorrect.
Overwhelming changes in anatomical structure would not be expected within the span of a meager hundred or even thousand years. The success of evolutionary theory does not depend on direct observations of sudden, dramatic changes in physical form (this would in fact undermine our understanding of it). Evolution makes successful, testable predictions of change. One testable prediction of evolution is minor variations and speciation, and speciation in transition, which have been observed:
1) New species variations of certain insects, plant species (via polyploidy), numerous microbes, et.al. have been shown to exhibit genetic speciation; i.e. inability to breed with parent species.
2) Ring species are blatant examples of speciation in transition, where extinction of an intermediate form would result in separate species free to evolve independently.
3) Existence of new species in unique environments that did not exist hundreds of years ago (i.e. read a bit about cichlids in Lake Victoria & Lake Malawi).
2. The homology argument assumes similarity of form could only arise from from common descent.
Wrong again. Discoveries in genetics have proven that homological similarities are correlated by genes. The same genes that are responsible for segmentation in worms are responsible for segmentation in humans. Genes affecting vision in fruit flies have been transplanted successfully to mice, etc.; if this isn't evidence for related ancestry, I don't know what it is you're looking for. Scientists have a quite solid understanding of how genes can replicate and alter to cause morphological variation. Your point about the independent evolution of eyes is quite moot - examples of vision, ranging from primitive light-sensitive cells to the complex eyes of squids (which in many aspects are "designed" much better than human eyes) exist because they are adaptations that result in a tremendous evolutionary advantage.
There should be many thousands of transitional forms...
There are. Anyone who knows anything about fossilization knows it is a scant process; no one would expect forms to perfectly preserve themselves in neat layers, nicely packaged for human discovery. Whale evolution has been demonstrated by transitional forms. No paleontologist ever tried to claim these forms are direct descendants of one another; they are most likely branches resulting from micro(macro?)evolutionary variations from the main lineage, but are still astounding evidence for the transition between land mammals and whales. And they are not the only example of transitional fossils - there are, in fact even better ones, in spite of the tenuous preservation of random fossilization - such as fish evolving to tetrapods, intermediaries between lizards and snakes, frogs and ancestral amphibians, gradual changes within fossil mollusks, at least 10 intermediaries between dinosaurs and birds, and yes:
Transitions between ape-like ancestors and humans are very well known (Australopithecus afarensis, Austalopithecus africanus, Homo habilus, Homo erectus, and primitive Homo sapiens remains with morphological similarities to more primitive forms.) Don't try telling me none of these are transitional forms; they definitely show a progression of ape-like to human characteristics.
The evidence for evolution is blatant and obvious. In fact, given how ubiquitous evolution is in the observable world, you'll have quite a difficult time explaining how it is that life didn't evolve radically over the 3.5 billion years of the observed fossil record; in fact, a well-documented general progression of life is shown through this time. (And please don't try telling me the earth is only a few thousand years old - you're really going to be in over your head if you do that.)
The truth is, evolution has stood up well and is accepted by virtually the entire scientific community (save a very, very, very few fringe extremists). Find me a fossil of a precambrian bunny or a caveman's spear impaled in a dinosaur and you might have something to go on. Evolution has been well-vindicated by science; the verdict is in.
Sorry, the 'Magic Garden Theory' just doesn't hold up to observational scrutiny, and has made no testable, falsifiable prediction that has ever withstood even basic scientific inquiry. Instead of making erroneous criticisms about evolution, maybe you should try to understand it better.
This very question shows an incredible lack of understanding of evolution. Of course, I'd ecpect that from the person who said:
There is no scientific research to prove evolution.
Talk about a tinfoil hat! The world's entire scientific community is engaged in some massive conspiracy?
It's hard to take such ignorance seriously.
You might want to actually read the posts in this thread before jumping into the middle of a conversation.
Which post did I miss?
Actually - that was an uncalled for comment.
Many times people arrive at a thread and respond to the original posting without reading the comments.
I hate when we "eat our own".
Later pingout.
Great.
Probably something similar to what we observe in a lancelet's eyespot, which is basically a collection of photoreceptive cells lining its nerve cord, pointing inward to detect light that passes through its tube-like body.
Human retinas show the same topography and are built with nearly identical genes. Human eyes have rods and cones (analogous to hairlike cilia in a lancelet's eye cells, which it doesn't use for vision) and other structures that have subsequently evolved, most of which have similar analogous structures in the more primitive lancelet (e.g. pigment epithelium), but are not used by the more primitive lancelet for vision, per se.
What does a small fraction of a developed eye give you? Something we observe in nature. We didn't evolve from lancelets, but basic similarities in our structure and genes give some indication of how our eyes evolved and shows how more primitive animals make use of a fraction of an eye. What good is 5% of an eye (give or take a few percent)? Look at a lancelet. It works for them. Like other examples of so-called "irreducible complexity", the eye really isn't one. No real problem for evolution here; in fact, we have a pretty good idea of how the vertebrate eye evolved, in spite of some of the flaws in its design.
Evidence meets the test of scientific scrutiny if it makes testable predictions that aren't falsified by observation. Evolution has succeeded in this regard, many, many, many times. When has any competing theory regarding life on earth done this? I would like to know. (Of course, the entire established scientific world is colluding to suppress alternative theories, right?)
BTW, TalkOrigins is a nice compact repository of info and links, but hardly a place I would rely on solely for knowledge on the subject.
Yes there is. Light-detecting neurons lining the nerve cord serve this purpose and they have the same topography as the photoreceptor cells on a developing vertebrate retina, and they point the same direction (backwards; a practical development for a simple lancelet-like chordate but hardly an "intelligent design" for a verterbrate).
The biochemical process in the eye does not compare to light sensative cellular structures.
What biochemical process are you referring to? Be more specific. The eye basically works like a camera, not by some mysterious unique biochemical process. Light enters the eye through the cornea; muscles contract the iris accordingly, then passes through a lens, through the vitreous humor (pretty much a near-transparent gel) and generates an image on the retina, which light-sensitive neurons, i.e. groups of cells, pass on to the brain. Yes, we have pupils that dilate and contract; we have rods and cones; we have a pigment epithelium; our eyes are definitely more complex than a lancelet's, but work the same way on some basic levels.
It's not an increasing sequence.
It is not a far stretch to consider subsequent evolution of additional structures in the eye. Rods and cones have analogous structures in the cilia of nerve cells. Lancelets have pigmented cells near the end of their eye spot very similar to the pigment epithelium that connects to the retina in the verterbrate eye. Membranes over the pigment cells could begin to take a lens shape, an obvious advantage of selection. Muscles developing to focus this lens would also confer an advantage.
Unfortunately, eyes do not fossilize well, so we may never know the sequence that particular developments of the modern vertebrate eye took place in, but eye evolution is definitely feasible. The argument of irreducible complexity holds no water here, as each of the aforementioned developments could result in an advantage in natural selection.
Try again.
I don't need to. You asked what good 5% of an eye is, and I gave a good example. You just don't like it. There are others, though lancelets might be the most relevant in living biological species.
The still unanswered question:
What successful testable prediction has any competing theory against evolution ever made? (Evolution has made many).
It's spam. But it's really GOOD spam. 8^>
bump to read later
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.