Cases Troublesome for Scientists

What cases in nature are the most troublesome for scientists to reconcile with the theory of evolution by natural selection? Are there any at all? Or are they so numerous that a top-10 list would be in order to get started?It seems to me that the case of ornaments for sexual selection is troublesome, because I found two competing explanations: one is Fisher's runaway explanation, and the other says an ornament advertises fittness and good genes because its owner is able to survive despite being handicaped by it. But maybe scientists do not consider ornaments troublesome, and it is only what scientists find troublesome that I'm asking about.Thanks,
IGIT Edited by InGodITrust, : added details

Hi InGodITrust,Could you edit your Message 1 and describe what the two competing explanations actually are? When you're done post a note to this thread or drop me a PM and I'll take another look.

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--	Percy
	EvC Forum Director

Percy, I edited the post. Any good?IGIT

Thread copied here from the Cases Troublesome for Scientists thread in the Proposed New Topics forum.

I think you might find what you are referring to is where scientist disagree. I'm not sure how this is problem. As we don't know all there is to know we can never be 100% sure that you are correct.The problems I antipate on this thread would be best described as competing theoretical standpoints.For example: I would concider 'depression' as an expression of cognitive and behavioural factors. Other disciplines within psychology would have a different formulation.But this is not a problem for science. It justeans we don't know enough to be more certain which theory is most accurate.

I think your example beautifully demonstrates the disconnect between your standpoint and that of a scientist. They are many questions in Evolutionary theory which are either unanswered, or where the potential answers have not been satisfactorily resolved one way or the other. You've given one example, I can throw in some more - the nature of pre-cambian evolution, why and how humans developed such remarkable brains, and naked skins, what patterns of rate change typify evolution, how much do random events influence the large scale pattern of evolution, etc.However, no scientist is going to consider these "troublesome to reconcile with the theory of evolution" (although some might quibble with the 'by natural selection' bit) because they're unanswered questions within the settled question of whether things evolve at all. To give an analogy, historians of the second world war will argue vociferously over how important this battle or that battle was, how much technology played a role, exactly how many Jews died in the camps etc., etc. but no serious 2nd world war historian is going to deny that there was a second world war, or that Britain, Russia and the US where on the same side fighting the Germans or that vast numbers of Jews (and Gypsies and homosexuals) were killed by the Germans in concentration camps, etc.

But how is this "a case in nature troublesome for scientists to reconcile with the theory of evolution by natural selection"? Apparently they have two ways to reconcile the case of sexual ornaments with the theory. This is positively an embarrassment of riches.It would make trouble for the theory if they had no explanation. Having two only leaves us with the interesting question of which is correct. (Note, by the way, that it is possible for one to be correct for one species and one for another, or indeed that it is possible for both to be correct for the same species.)

it is also possible that neither are correct for a species and that there is still a yet unknown mechanism waiting to be discovered.regardless, science is expanding its knowledge base. will we ever know everything? no. but that doesn't mean that the things we do know are invalid.

Okay, fair enough; scientist do not find any cases particularly troublesome. Thanks.My example of ornaments may have been a bad one. I wasn't sure how scientists saw it. But as a lay person, the explanations seem weak. Not just because competing explanations are entertained, but because the explanations seem strained and barely viable. Darwin would not have arrived at his theory by contemplating the crazy plumage of some birds; rather, he had to find a way to reconcile the plumage with his theory.But forgetting about crazy bird plumage, as I now know from your replies that this is not something that is vexing scientists, I wonder about any cases of organisms with features or behaviours that do vex scientists as to how natural selection is responsible. I wonder if, starting with natural selection as a given, there are cases in which scientists struggle for an explanation that fits in.Mr Jack, your reply, "some may quibble with the 'by natural selection' bit" tells me there are cases of evolution for which at least a percentage of scientists struggle to see how natural selection is responsible. This is interesting to me, because I had thought that scientists attributed all evolution to natural selection, aside from the chance asteroid wiping perfectly good species. But in the aftermath of the asteroid, or other upheaval, don't scientists believe that natural selection guides all evolution of the survivors?

That's not quite what I said. The consensus view is that natural selection is the primary factor in evolution, and certainly the only one that is actually capable of producing meaningful adaption, however there is disagreement over the extent to which non-selective forces are important in determing the path of evolution. I think all evolutionary scientists accept that there are non-adaptive features of evolution (from genetic drift to pleiotropy) but there is disagreement as to their influence.But, again, these are disagreements about the details not the overall picture.

Okay, thanks Mr Jack. I need to look into the non-adaptive features when I get time.IGIT

"Crazy plumage of some birds" is one of the pieces of evidence Darwin used to support his theory in Origin of Species. This is from the section on sexual selection: So Darwin quite obviously contemplated crazy bird plumage while formulating the theory of evolution. Natural selection is what produces adaptation, so you're seeking characteristics for which evolution has produced reduced overall adaptation. I can't think of any such characteristics off the top of my head, but there must be some, and scientists probably wouldn't try to explain them using natural selection. I think it was WK who already mentioned a couple other factors that contribute to the path of evolution, like genetic drift and pleiotropy.--Percy

And this points out the failure of InGodITrust to understand even the basics of evolutionary theory. It is somewhat ridiculous to point out examples of sexual selection and wonder how they are explained by natural selection. The mechanisms of evolution are not limited to merely mutation and natural selection (even though InGodITrust didn't mention mutation). There are several mechanisms of evolution that have been observed. Some of those mechanisms tend to increase genetic diversity (and thus change allele frequencies in a population) while others tend to decrease genetic diversity (and thus change allele frequencies in a population). Mechanisms that increase genetic diversity are mutation, gene flow, movable elements (transposable elements), and recombination. Mechanisms that decrease genetic diversity are natural selection, genetic drift, biased variation, and nonrandom mating (sexual selection).Sexual selection isn't a problem for natural selection. In fact, such sexual traits as "crazy plumage of some birds" developed, not because it is beneficial to survival, but because it lends differential reproductive success, i.e., females prefer such displays. And while such displays may not be helpful to survival, they may be offset because such displays are typical of exceedingly fit individuals that can overcome the disadvantages and survive to reproduce. After all, it is survival to reproduce that is important and not pure survival.

OK, could you please tell us what you're trying to get at? So far, all this thread seems to be getting at is that you are trying to find some way to doubt that natural selection is responsible for evolution, but that does not preclude the fact that species have indeed evolved. So then, are you seeking to disprove only certain mechanisms for evolution, or are you seeking to disprove that evolution has even happened?Describing the obvious to you, there are two very different questions involved here:
1. Did and do species evolve? (AKA "the fact of evolution")
2. By what mechanisms did they evolve? (AKA "the theory of evolution")Which question are you concerned with? Are you by any chance aware that not knowing how something happens has absolutely no effect on whether that something actually happens? The fact of something happening is independent of attempts to explain how it happens. Is there some part of that that you do not understand? Because it very much looks like that is the case, that you indeed do not understand very basic concepts.Know the enemy and know yourself. What part of that do you not understand? You are still keeping your eyes tightly shut and firing blindly in all directions hoping to inflict some kind of damage on evolution, but all you ever succeed in hitting is your own foot. Each and every time you attempt something like this.Instead of repeatedly shooting yourself in the foot, shouldn't you instead try to learn something about evolution?

An excellent point. As an example, we have no idea as to why an apple falls to earth, we only observe that it does. We label our lack of understanding "gravity."