- Anything Else -

Not exactly.

Posted by: Floyd ( Darwin Fan Club, Unrepentant Selectionists Association ) on October 05, 1999 at 14:22:38:

In Reply to: Whales have lungs because they were created that way... posted by Nelson on October 03, 1999 at 19:41:28:

: (SNIP) First of all....yes, things adapt to their environment. They have to or they die. Simple. Bacteria do a very good job as you know. However, the point that someone should be making here is this. The bacteria in question is still bacteria. It hasn't "evolved" in to something else. It has just survived by producing those who are resistant to the drug......and so on and so on.....

Actually, what you're critiquing here is not evolution, in the Darwinian sense, but something called "saltation," which is anethema to Darwinian theory. You note that selection is operating, you recognize that variants that are best adapted to their environments persist and multiply at the expense of the less well adapted. You are aware that the variations that make an organism more or less adapted are heritable (i.e. "offspring" get them from their "parents") and you can see that changes in the environment tend to favor different variants within the gene pool of a population. You are, therefore, a very strict Darwinian. Your hesitance to accept this is due to a common misunderstanding about what "evolution" actually means.
"Evolution," in the Darwinian sense, is pretty much as you describe natural selection. Darwin never suggested that fish give birth to mammals or that reptiles give birth to fully-formed birds. In fact, Darwin explicitly argues that this is not possible. Instead, minor changes, like those Farinata details in bacteria, are compounded over the course of many generations, and that populations that inhabit different environments will tend to diverge, genetically, from each other, due to the different changes in their respective environments, and the fact that the appearance of new genetic variants is "random" (Markovian, technically) with respect to selective pressures. Over time, these divergences will add up to the point where the genetic code of one population that is isolated from its sister populations will become so different that reproduction between members of the two populations will be impossible, since the appearance of exactly the same mutant genes in both populations is a statistical "impossibility". This is what "speciation" means.
Farinata used the example of bacteria because they reproduce very quickly, and human observers can view hundreds of bacteria generations within one human lifetime. Other researchers, most notably Lewontin, use the genus Drosophilia, the fly, for the same reason. It's true that, over the course of a hundred or so generations, bacteria won't evolve into elephants or oak trees, but so what? It's not about what the descendants of isolated populations become, but about whether or not they are the same species. Evolution above the species level takes even longer, and because our concept of "genus" is less operationally defined than our concept of species, it is often harder to see. (Paleontologists have this problem all the time. "Is fossil X different enough from fossil Y that we can call it a distinct genus, or just a distinct species of the same genus?" Watch for arguments in paleoanthropology about whether the recent discoveries in the Afar are appropriately called Australopithecus garhi or Homo garhi for example.)

:It's a classic "Peppered Moth" example. I belief in natural selection. It is observable and it has been proven. It is an obvious force in our world. However, natural selection has never changed a lizzard into a bird or anything of the like.

Well, actually, it has. (In fact, probably at least twice!) Recall that any reptile that developed a more effective heat-regulating mechanism would tend to out-compete its conspecifics for resources and mates, and thus leave more offspring. Since the efficiency of the heat-regulating mechanism is based on the genes of the reptile, it is heritable. Within generation G+1, the "children" of the mutant reptile will also be variable, and some of them will have even better heat-regulating mechanisms than their parents, and thus reproduce more. The same will be true at time G+3, G+4...G+n for n generations. If this heat regulating mechanism was in the form of elongated, expandable scales, the form of feathers is an obvious eventual result, since they are chemically identical to scales, but shaped slightly differently. Assume, at the same time, that this reptile was bipedal, as were many of its ancestors, and that it used its upper limbs for stablizing it as it ran. The gradual elongation of its scales (as they approach what we would recognize as feathers) will also tend to offer a slight degree of lift, and thus provide the reptile with an increased ability to jump slightly higher, and thus catch insects or reach fruits that its conspecifics can not. Again, we get differential access to resources, and thus differential reproduction. By generation G+n, we are looking at something that has a basically reptilian skeleton, but posesses feathers and can fly, at least for short distances. In other words, a bird. Now, you are correct that a fully-formed reptile never gave birth to a fully formed bird, that would be quite impossible, but at what point did this evolutionary trajectory stop being a reptile and start being a bird? The answer is that this is an unanswerable question. There is no "transformation" from reptile to bird, and Darwin argued that none is necessary.
In fact, such a transformation would be very strong evidence against Darwin, as it would require the operation of a force unlike any known in nature. An instantaneous transformation like that would actually be impressive evidence in favor of the active interference of a god in the natural world, and against evolution. As you point out, such evidence does not exist.
Also, it's not exactly a "peppered moth" example, since the two variants of moth were not ever reproductively isolated, while the bacteria Farinata discusses were. The mechanics are slightly different, but this is not the place to discuss this issue.

:Whales have lungs because they were created that way...not because they were fish who decided they wanted to breath air on land and then later changed their minds and wanted to live in the water again.

Since we have the fossilized bones of land-dwelling whales, as well as many of their ancestors, I'd like to hear how you account for these remains. I'm not being facetious here. I am really seriously interested in how you would account for these remains.

:I'm making fun now, but think about it. The evolutionist has to have way more "faith" than the Christian who supports a divine Creator.

Actually, no. Evolutionary theory requires almost no "faith" whatsoever, simple observation of the present conditions and extrapolation of those observed conditions into the past is sufficient to account for all organisms, both extant and fossil. The only "faith" needed is the belief that the conditions of the past were in many ways similar to the conditions of the present, and that is much more parsimonious that the assumption that past conditions were dramatically different and included forces that are no longer operating.

Now none of this, as I've said repeatedly (but no one ever seems to listen), has anything to do with whether or not there is an old white guy with a long beard and super powers living in the sky. The Judeo-Christian-Islamic version of a god may, in fact, exist. Science can't address this question, and so I must remain agnostic. IF (and this is quite a big if) there is a being like these religions describe, then "he" uses evolution as part of his "tool kit," just as sure as he uses gravity and electromagnetic repulsion. We see it in action, so if he exists, he's using it.
-Floyd
P.S. check out Foley's Talkorigins website for more details.


Follow Ups:

None.

The Debating Room Post a Followup