Jzyehoshua writes:
However, I didn't see Dr. Adequate bring up this point. All I was hearing was, "unless you prove you're a scientist you have no room to say anything on this forum", a requirement I'd been unaware of. Naturally this appeared belittling, condescending, arrogant, spurious, and a direct assault on the American ideal of freedom of speech.
Like I said before, pay no attention to Dr Adequate. He gets on everyone's nerves. He gets suspended a lot, too. He apparently enjoys brinksmanship and occasionally the brink gets him.
Perhaps it would have been more accurate if I had said, "What I think Dr Adequate is reacting to..."
Jzyehoshua writes:
My point is that while we keep hearing about the ability of animals to make drastic evolutionary leaps between species, we have yet to see any evidence of it.
I don't think anyone sees evidence of "evolutionary leaps between species." An organism cannot differ genetically from its parent (or parents) by more than the few mutations it might happen to receive as part of the reproductive process. Evolution proceeds in very tiny, incremental steps. Evidence for "leaps between species" would be evidence against evolution.
As the Brothers Winn point out, we've been watching bacteria since the invention of the microscope, and while they have adapted as bacteria, they've never become a new, higher form of life.
Imagine if evolution could actually express desires. Bacterial evolution a billion years ago before there was any multicellular life at all might have thought to itself, "Gee, if I could just team up with other bacteria to form a single multi-celled organism then I could get more food and grow even faster because there's no competition at that size."
Bacterial evolution today might say, "Gee, if I teamed up with other bacteria to form a single multi-celled organism then there's tons of very advanced competition that has had nearly a billion years to evolve great skill competing at that level. Better to remain a little bacteria."
Of course, evolution cannot express desires, and in fact evolution is directionless and just reponds to current environmental factors, but I'm just making the point that the ecological niches for multi-celled organisms are very crowded today, so bacteria gaining a foothold at that level would now be very unlikely. Still, some bacteria do cooperate and so have what could be considered very primitive multi-cellular capability.
But bacteria
*do* evolve. The reason they're so often the subjects of studies is because they evolve quickly due to very short generation times. For example, some species of
E. coli reproduce every 20 minutes.
Same with canaries. They may adapt within an apparent parent species, but do not become an entirely new line.
Canaries evolve too. All life evolves. Reproduction requires the copying of DNA, and the copying process is imperfect. The average human (and probably the average canary, too) has about 100 mutations, meaning portions of their DNA that they did not inherit from either parent but that came about through copying errors.
Bacterial evolution can be easily studied because in short periods of time, like a month, you can get a couple thousand generations and literally billions and billions of reproductive events. Evolution in longer lived species is much more difficult to study in the lab. In a month you would be luck to get one new generation from Canaries. In a year maybe you could have three generations and maybe a couple hundred reproductive events at most, since usually the parents won't breed again until the current brood leaves the nest. Given that each offspring differs genetically only minutely from its parents, canaries aren't going to evolve much in such a small number of generations.
I'm not aware of any evolutionary studies of canaries, but studies of the finches of the Galpagos Islands have been widely publicized, and those finches do change in minor ways in response to environmental changes.
Were we still actively considering parent species as an alternative, which Darwin himself stated as the opposing view, then the evidence would appear telling that this is the case, and an objective examination lead to more thorough analysis of the competing possibility.
The genetic evidence pretty conclusively excludes the possibility of multiple unique evolutionary origins for extant species. I wonder if we could figure out a way to go over that evidence in an on-line discussion. There's a couple biologists here. WK?
However, this has also resulted in certain infamous fossil finds which were falsified (Java Man, Piltdown Man, Nebraska Man). It has also resulted in several surprising mistakes recently, such as the discovery the newly christened 'rat squirrel' was in fact the already existing
Laotian Rock Rat, or that
Homo Floresiensis, aka hobbit man and labeled a missing link, had in fact lived up until modern times and thus could not be an ancestor, or that
Habilis and Erectus lived at the same time and would have to be knocked off the lineage, or that
Ardipithecus Ramidus, older than Lucy, looked nothing like an ape and walked upright. The news has had major press received that the
human family tree is now instead a 'bush' with dead ends everywhere.
Classification can be difficult. Let me explain why disagreements about and changes in classification have no bearing on the theory of evolution using the analogy of a tree. Imagine you and a friend are beneath a tree, and you look up at a clump of leaves in the canopy. You both look at one particular leaf and find if difficult to tell which branch of the tree the leaf belongs to. You and your friend argue about it. You finally climb up into the canopy and discover that the leaf actually belongs to a third reaching branch that neither of you had noticed.
But at no time during this resolution of a difference of opinion did either of you ever doubt the branching nature of trees. Leaves connect to twigs connect to branches connect to bigger and bigger branches and finally to the trunk.
In other words, differences of opinion about which branch a species belongs in does not call into question the nested hierarchy of life. And just as with the tree leaf where you were able to resolve the difference of opinion by climbing into the canopy and conducting a closer examination, we can remove all ambiguity about classification of life by closer examination through sequencing of the DNA.
Of course, with fossils DNA sequencing isn't possible, and so scientists are like you and your friend when you were both on the ground staring up at the leaf. Without the additional information of DNA sequencing there will always be room for disagreement.
Again, not only is there a complete lack of proof for this interspeciary change, but discoveries are beginning to knock out one after another of the missing links that already exist, or else alleged new ones are found wrong.
I think you're probably referring to disagreements over and changes to classification, which I just explained, but if not can you be more specific?
--Percy
™ Version 4.2