posted
I found myself rather annoyed at this essay, actually. I'm currently reading the Shadow series and am frequently impressed by Card's ability to write Bean as well as he does; his rational analysis of given situations, such as the state of the world political/military stage, even when he finds himself henpecked by adolescent hormones, is substantially astute (sure, he's just "predicting" developments Card intends to use -- he's a lot like the character in a movie who hears the audience telling him the killer is in the next room -- but his analysis is so much more than that), so it frustrates me that Card's own analysis isn't similarly so.
The entire first half of the essay is sloppy, unresearched, and practically devoid of anything approaching a real or fair argument. His characterizations of "Darwinist" arguments are oversimplified to the point that they can be presented as obviously wrong. I've never met an evolutionary biologist, or even a layperson who's studied evolutionary biology (or any of the other disciplines that support and even depend on evolution for the science to work) who dismissed sincere, real questions with "name-calling" and "elitism."
There's a difference, though, between asking questions and Intelligent Design. Intelligent Design doesn't say, "that doesn't work, and here's the science of why," it says "that doesn't work because I don't believe it can." ID is unscientific chiefly because its sole source of information is the personal incredulity of the individual rather than falsifiable, testable experimentation.
Also, using Michael Behe's work to defend his position should be an embarassment; I, as a layperson, can out-argue Irreducible Complexity, and that's the cornerstone of Behe's entire argument. He may be a scientist, (a biochemist), but that doesn't mean he understands evolution, and his IC proposal demonstrates pretty well that he doesn't.
The second half of the essay was more sensible, as he seems to be opposed not to evolution but Darwinian evolution, which even Darwin found problems with, some of which he was able to answer and some not. I agree with him; if schoolchildren are being taught Darwinian evolution straight from Origin of the Species, they should stop. They should instead teach modern evolutionary biology. Adding Intelligent Design to the cirriculum isn't the answer to the problem, new textbooks are.
Finally, people who accept evolution as scientific fact are not "evolutionists" or "Darwinists" any more than people who accept gravity as scientific fact are not "gravitationalists" or "Newtonists." Those terms serve no useful function.
Posts: 1 | Registered: Jan 2006
| IP: Logged |
posted
Well, they DO serve to overemotionalize the debate, which is always important, no?
I can't think of any textbook that teaches anything other than that Darwin (and Wallace!) were the fathers of evolutionary theory which has long since developed beyond their authority or conclusions.
Posts: 11 | Registered: Jan 2006
| IP: Logged |
posted
I've had it with this debate. I'm taking my genes, and I'm going home! None of you are invited to my birthday party.
Posts: 9912 | Registered: Nov 2005
| IP: Logged |
posted
Minerva, we've actually known for some time that all sorts of major chromosome level changes can take place without necessarily causing sterility or even death. Human beings have a chromosome that is simply two chromosomes fused together. Since all apes have these two chromosomes as separate, this fusion must have happened sometime after we diverged from other living apes.
In humans TODAY, there are many examples of major genetic changes in chromosome numbers that do not necessarily cause sterility. Females with Down syndrome can reproduce, and pass on the trait 50% of the time. Many rarer chromosome conditions that do not cause so many health and developmental difficulties also allow viable reproduction to take place.
The flexibility of genomes is different from creature to creature depending on their exact genetic structure (making things VERY VERY complicated: far too complicated to explain all the ins and outs in even a small book, much less a post). Mice, for instance, seem to have chomrosome fusions, deletions, duplications and the like happening quite a lot in their various speciations. Plants are exceedingly tolerant (which is why they vary so much in their ploidy: some hybrid plants even have up to six copies of every chromosome!)
Posts: 11 | Registered: Jan 2006
| IP: Logged |
posted
I wanted to address some of the basic points here as well, going back to the points about species vs. genus, and so on. Tarrsk definately covers a lot of the key ground, but I think more can be said about macroevolution in general.
First of all, like Tarrsk said, there is no way to prove definitively that common descent (often refferred to as the "fact" of evolution) was all entirely the result of natural selection, anymore than we can prove that every sunrise in history was the result of earth's rotation.
In fact, this "natural selection explains everything about life" is a common straw man, because no biologist I know of claims that natural selection is the only force acting on the path of history in the common descent of species (even Darwin didn't think so). Any number of macro-evolutionary processes, from the neutral theory, to genetic drift, to mass extinction, to PE and others are thought to play a role (though where and how and when are all contentious matters) and are well within the accepted mainstream. Natural selection, of course, remains the only process proposed that can shape function and add "information" to the genome, and as such retains its central explanatory role as making adaptation, long term functional improvements over time, and other such constructive results possible.
As far as the proof that macroevolution in general happened, that common descent links all forms of life, this conclusion is basically unavoidable given the evidence. There may be, indeed, no more well established fact about the history of our planet. Nothing else aside from geology has such a broad scope of indepedent lines of evidence that all converge in such otherwise inexplicable detail, with the history and evidence spread across the entire globe. While specific historical events and sequences elude us, and may always elude us due to the evidence being destroyed, the general overview is sound. Fossil evidence fits in amazingly well with the patterns of the geographical distribution of life which is itself consistent with the geological history of continents, seas, land barriers, and so forth. The taxonomy of living things unswervingly conforms to the exact pattern that common descent demands: nested clades of traits, "allied" groups within groups.
Adding in the fossil record into this classification system only deepens the relations, fleshes out the already unavoidable implication that similar forms have some relation to each other. Countless transitional fossils, bearing blends of traits that are otherwise unique to different modern groups, strengthen the conclusion.
All of this was compelling enough already until the advent of genetics. Once we discovered ways to delve into the exact mechanisms and records of heredity, the reality of common descent became largely unavoidable. It wasn't simply that genetic studies showed so much in common between different creatures. It was the patterns of relation that the genes spelled out amazingly fit many of the patterns of ancestry that the fossils had already spelled out. That these two entirely different comparisons should match up is simply amazing: unless common descent is true, there is no reason for them to match, not in such detail, not in this particular way. In time, genetic studies even led us to fossils for more unknown historical transistions.
For instance, genetic evidence confirmed what had once been a fringe theory about whales and dolphins evolving from a particular sort of land animals, their closest living relative being the hippo. Once scientists knew this, they knew where to look for the ancestors of the whales (who in modern days range over so much of the ocean that we had never known where they might have started). And, amazingly, this new direction turned up several key transitional fossils sharing traits that are today unique to both land mammals and whales.
Genetics has allowed us to turn on long silenced ancestral genes, such as legs in snakes or the entire missing "adult" stage of the axotol. It has also revealed the mechanics of things like reproductive speciation: how mutations can begin and end the split of one population into two.
There is so much more one could go into to show why common descent is such a certainty: the particulars of hybridism, atavisms, population genetics. Each proof is not just another brick in the wall: it's a piece in a huge multi-dimensional puzzle that fits together in a coordinated way that could never ever happen if many or all the proofs were in error: error has no mechanism for coordination.
But this still brings us back to natural selection as the core of why and how this diversity is acheived, HOW these forms descend from each other with increasing modification. In many cases, especially those beyond the helpful guide of fossils and so far back in history that genetic evidence become confused and cloudy, we don't have much evidence to direct our invesigations. We are left, oftentimes, with many plausible pathways for some feature to evolve, but no way to distinguish what was merely possible from what actually happened.
Nevertheless, it is likewise quite certain that natural selection has been the primary driving force for adaptation and the construction of complex structures. No other explanation has both the potential the capability and the demonstrated means. Natural selection, which has been modeled and reproduced as a design process in all sorts of fields beyond biology, results in very particular sorts of outcomes. Its results tend to be repetative, wasteful, indirect, meandering but also often unpredictably ingenious. And here too, in genes and in physical function, we find that the functions in biology are often not only complex but needlessly, wastefuly complex and almost rube goldbergian. We find them built out of structures that appear to be modified duplications of previously existing structures rather than new parts. We find the history of common descent to be characteristically slow in getting to the point (otherwise obvious good tricks and traits taking hundreds of millenia to crop up)
That's only a sketch, but that's why even a layperson can convince themselves that evolution (micro, macro, common descent) is the best explanation anyones so far come up with, the one that fits the evidence so well that anyone seeking to disprove it faces an uphill climb to discount or explain not just any single piece of evidence or raise a doubt about this or that detail here or there, but the grand convergence of almost all of the physical evidence we have.
Posts: 11 | Registered: Jan 2006
| IP: Logged |
Printer-friendly view of this topic
