In
my
last post, I discussed an analogy, often used by evolutionists,
to show how one species can change into another via tiny mutations
over a long time. In that analogy, the author turned the word
AARDVARK into BASEBALL but changing one letter at a time over 6
generations. It's a gross over simplification and one complaint I
have with it is that evolution is not supposed to be a directed
process. The author of the graph knew he was heading toward BASEBALL
so he only selected changes that made the word more like BASEBALL.
In the real world, natural selection doesn't know the arm is supposed
to become a wing. Instead, natural selection will select a variation
of an arm that is a
more-fit-arm over a more-like-a-wing arm.
Evolutionists
scoff at my criticism. Their usual response is that it's just an
analogy and not meant to be a scientific model of how evolution
works. Evolution, they say, is fine with any outcome. If not
BASEBALL, it could become GIRAFFES or PENGUINS or WHATEVER.
Oh,
really? What, then, is Batesian mimicry except directed evolution?
From Study.com,
we find the following description of Batesian mimicry:
One
well-known anti-predator adaptation
is Batesian mimicry. This describes a relationship where one organism
that is harmless has evolved
aposematic coloration that mimics a noxious species. A noxious
species has some sort of harmful or damaging protection, and
aposematic coloration is a distinctive warning marking that sets the
noxious species apart and makes it easily identifiable. By
imitating a harmful species, the mimic can avoid predation.
(bold added)
In
more ordinary language, this form of mimicry is when a harmless
creature (called the mimic) possesses similar colors/body shape as a
poisonous creature (called the model) which tricks predators into not
trying to eat the harmless creature.
Hmmm.
It seems like they're saying some species evolved specifically to
look like another species for the purpose of avoiding predation.
Design and purpose. It sure sounds like it was intended. Of course,
they can't really be saying that because evolution is not a directed
process. Through random
mutations and undirected
natural selection, some species just happen to strongly
resemble some other, completely
unrelated
species. Yeah, sure. That's it. //RKBentley rolls his eyes//
How
strong is the resemblance? See for yourself. In this photograph,
one bug is a Robber-fly, which may be annoying as most flies are, but
has no sting or bite. The other is a bumblebee. Even with close
scrutiny it is easy to confuse the two.
Certainly
they look alike. How did the mimic evolve to look so much like the
model? Keep in mind, too, that both bugs are believed to have
evolved so the bee did not always look like it does now. Therefor,
the mimic couldn't have just evolved to look like how the bee looked
100 million years ago; it had to evolve to look like how the bee
looks now. So we have a couple of options: maybe the bee evolved
first, stopped evolving, and hasn't changed since thereby allowing
the fly to catch up. Or, maybe both evolved independently over
millions of years and reached their similarity by sheer coincidence.
How fortuitous!!
There
are hundreds of examples of mimicry found in nature. Besides
mimicking dangerous models, some mimics resemble plants or sticks,
like this leaf-tailed gecko. Still others, like the octopus, can
even change its shape and color to match its surroundings. Are all
of these cases coincidental? Or did natural selection guide
the process as if intentionally making the mimic look like the model?
Either option is hard to swallow.
I've
read evolutionists' fanciful stories as they seek to explain what
clearly seem to be examples of design with purpose. No matter how
far fetched their explanations may seem, they prefer their natural
causes over the far more reasonable possibility that they were
created
that way!
I forget where I first read this (Dennett's Darwin's Dangerous Idea, I think, but I'm not going to look it up). Anyway, he cites a hypothetical example: you're taking a tour through the woods, and you find a moth that is perfectly camouflaged to match the forest floor. The tour guide explains that this arose through a process of natural selection: in each generation, the moths that were least conspicuous against the forest floor survived to pass on their genes. Then the tour guide goes on to explain that if the forest floor looked different, the moths would have evolved to match that pattern. This is wrong, or at least not necessarily right; it may be that the current pattern is one of the few that the moth was actually able to evolve. If the forest floor looked different, perhaps some other lineage of insects would have had mutations that made them slightly less conspicuous, and that lineage would have produced a species that was perfectly camouflaged against that different forest floor. The point is, you see the successes of natural selection acting on random mutations; you don't see all the cases where an adaption did not arise, where there simply weren't the relevant variations to select.
ReplyDeleteIt was Dawkins, in, I think, Climbing Mount Improbable, who noted that being camouflaged is a relative matter. Very imperfect camouflage -- a very slight difference in color or pattern from its kin -- might save an organism's life from a predator with poor vision, or a predator with good vision but viewing the scene from a distance in poor lighting. It does not take good camouflage to provide a meaningful (albeit small -- recall that casinos stay in business through small advantages) increase in one's chance of passing on one's genes, and hundreds of generations of iterations of this process can perfect the camouflage.
Or, conversely, a quite small resemblance to some obnoxious animal might make a predator turn after prey that didn't look so dangerous. Perhaps the predator is simply not looking closely enough on many occasions, so a slight resemblance is sufficient deterrent. Or, experiments show that baby animals and potential mates are often attracted to some single small trait of the parent or potential mate, not the whole complex gestalt; one might reasonably surmise that many animals are repelled by some single aspect of a predator or dangerous prey. So a single change that doesn't, to us, make the harmless animal look very much at all like the dangerous one might be enough to convince an entire class of predators to leave it alone, increasing its chances of survival so that later mutations can add yet other traits that deter other predators until the disguise is complete.
The "guidance" is that members of the species that aren't so effectively disguised are more likely to be eaten every generation, so each generation their genes become rarer in the population, while conversely, any gene that improves the resemblance, even slightly, is likely to be conserved and spread through the population. There's no magic and little enough mystery, really.
One further note: in some instances, it's not clear whether we're observing Batesian mimicry (convergence of appearance of a harmless species on a poisonous or otherwise dangerous one) or Mullerian mimicry (convergence of two dangerous species on each other in appearance -- evolution of a sort of standardized hazard signal).
A second further note: why is creation a better explanation? A writer, Tom Scharles, on the Talk.Origins website, noted that we see animals equipped with camouflage to evade predators -- and predators equipped with keen senses to defeat camouflage in prey! You are invoking intelligent design to explain two designs with diametrically opposite and incompatible functions. To what conceivable point? Should we invoke multiple, rival designers? A single Designer working for multiple, rival clients?
Steven J,
ReplyDeleteFirst, as I've said many times, natural selection doesn't compare the current form to the final form. Thinking a slight change that makes the mimic more like the model will be selected is like saying natural selection would prefer the arm that is more like a wing over the arm that is a more fit arm.
Second, the sheer number of examples of mimicry should give you cause to doubt your theory. Remember, it's not just natural selection preferring mimics that most look like the model, it's random mutations that create the colors/shapes that are compared. What are the odds that random mutations over countless generations would give a fly nearly the exact same colors, patterns, and body shape as a bee? Now what of the odds of that happening in a hundred other species?
It's like I said, your side offers “fanciful stories.” You're welcome to believe them but they're hardly scientific. Imagining a possible pathway for mimicry to evolve is not evidence that it happened that way. Conversely, I would say the obvious appearance of design and purpose are empirical evidence for creation.
Thanks for your comments. God bless!!
RKBentley
First, natural selection is not the sort of entity that can "prefer" anything; indeed, it is more of a result than an entity.
ReplyDeleteSecond, there is no "final form," except in the case of lineages that go extinct; you are not justified in assuming that any current species or adaption within a species is the "final form" of a process.
Third, if an arm, by having longer feathers, makes gliding easier (in a tree-dwelling animal), or just makes the animal more attractive to potential mates, then it causes the arm to be more fit. There is no global, absolute criterion for "fitness;" what is fitter in one case is less fit in another. Also, as I pointed out, an arm can become very wing-like while losing little or no utility as an arm, as we know from fossils of Archaeopteryx and Microraptor or Caudipteryx.
Fourth, you persist in arguing as if natural selection and mutation can somehow be mutually exclusive. Random mutations that survive and propagate non-randomly do not constitute a random process. Natural selection works on millions of mutations occurring in each generation, throws most of them away, conserves a few. That does rather more to improve the odds than you allow (the letter-based simulations you discussed in your previous essay are designed to show off the difference between cumulative selection and one-shot random selection; they are not intended as ideal examples of every aspect of evolution).
Fifth, again, the obvious implication of design and purpose that work towards clearly opposite ends (e.g. the predator finding prey and the prey thwarting this attempt) is that there are multiple, competing "designers" -- or one "designer" working simultaneously towards multiple incompatible ends with no overarching purpose. You have not addressed this point.
Sixth, reproduction, inheritance, mutation, natural selection, adaption, and speciation are all observed phenomena. Designers poofing complex new systems into existence without physical mechanisms are not, and invoking such a designer (especially, as noted, as the single simultaneous explanation for designs that are obviously antagonistic) is rather a fanciful story on its own.
Steven J,
ReplyDeleteIn mimicry, I'm assuming the model to be the final form. According to evolution, bees evolved, what, 125 million years ago? If the mimic has perfected its resemblance to the bee, it will be a fleeting benefit if the bee changes form through continuous evolution. Which shines on a light on the problem of how the mimic evolved the resemblance over the million year history of the model's evolution: the model changes – the mimic changes – the model changes – the mimic changes. Alternatively, if they didn't always look alike and won't always look alike, then how fortunate we are to be alive at the precise moment when so many examples of models/mimics exist.
To your point about predators who aren't fooled by mimics, I would say it's a lot easier to understand that than how mimicry could have evolved. For example, some animals have become color blind through mutation. This mutation may result in the host no longer being able to see the camouflage or coloring of the mimic and the body styles are distinct enough that the predator can distinguish the mimic from the model. A single adaptation could help a predator identify a mimic; how is that a problem for creation? It certainly pales in comparison to the problem of how mimicry could have evolved in the first place.
Finally, mutations may be necessary for evolution but they aren't necessary for natural selection. Natural selection is fine testing traits already present in the population. Indeed, that's all it can do. It cannot test traits that don't already exist. Mutations could theoretically add a novel trait to a creature that would then be acted upon by natural selection but, as I've said many times in the past, beneficial mutations are exceedingly rare. There's not a single, convincing example that I've seen. Believe me when I say that I've looked for them. For evolution to happen, novel features would have to appear in nature with regular frequency. If I were an apologist for evolution, I would blog about nothing else than examples of novel features appearing in populations. I wonder why there aren't any evolutionists doing that already? He he he.
God bless!!
RKBentley
Steven J,
ReplyDeleteAdded in edit. I didn't mean to say "beneficial mutations are exceedingly rare." I meant mutations that add new features are exceedingly rare. Color blindness, like I had just mentioned, is a mutation that could be beneficial but it represents a loss of function. I'm looking for convincing examples where mutations add a new feature/function.
Sorry for the confusion. Carry on!!
RKBentley
For sufficiently mild meanings of "exceedingly," beneficial mutations are exceedingly rare. I doubt anyone puts the proportion as high as one percent, and they're generally assumed to be significantly rarer.
ReplyDeleteGain of function mutations are known, though rare. Note that they are not necessarily beneficial; if you're born with a mutant protein that has some previously absent function, it's like being born with some random experimental drug circulating around inside you. The effects might well not be pretty. The only beneficial mutation I know of that is also definitely a gain-of-function mutation is the Flavobacterium mutation (thought to be a case of gene duplication followed by alteration of the duplicate gene) that gave one strain of the aforementioned bacterium the ability to digest nylon waste in the pond where it grew.
If you have some more restrictive meaning of "new feature" (e.g. a new organ or limb), it is even harder to find a clear case (the appearance of cecal valves in the intestines in Italian wall lizards stranded on the island of Pod Mrcaru presumably counts as a "new feature" in these lizards, but related lizards have such valves and it's not clear what -- or whether -- mutations were involved in their appearance, or whether these were "gain of function" mutations).
I note in passing that we have pretty much the same organs and limbs as mice, or even kangaroos (or indeed, even frogs). Evolution does not require the frequent appearance of radically new structures in populations.