Darwinism Cannot Explain The Peacock

Hi, Arriba.Welcome to EvC!I'm glad that you've brought this to our attention: it's an interesting study with very relevant results for the evolution-vs-creation debate.However, I'm a little dismayed by the way you've drawn conclusions. I haven't read the Ioannidis article you talked about, but, based on your paraphrasing of the article's conclusions, I think you have fallen victim to the same biases you discussed, and of which you accuse evolutionists.For example, you seem to have exercised confirmation bias by sharing with us the paper that rejects the sexual-selection hypothesis of peacock feather trains, but have neglected to mention the following papers, which have upheld modified versions of the sexual-selection hypothesis: -----The first paper shows that feather-train length of male peacocks is, in fact, correlated with some measures of male fitness. However, they found no evidence that feather-train length directly influences female mate preferences. So, perhaps feather train is a side effect of the real selective signals?The second paper shows that ornamentation does indeed have a positive impact on reproductive fitness, but with considerably less precision than was previously thought. So, fine-scale variation in ornamentation does not influence female decision, but large-scale variation does.The third paper shows that other characteristics of the peacock can potentially modify the peahen's decision-making process: specifically, the crest on the male peacock's head is correlated better with some metrics of health and fitness than is the feather train, and may provide a finer-scale stimulus in female mate preference.The final paper deals with wolf spiders, but shows that in some settings, complex ornamentation has less benefit than in others. These peafowl studies are generally conducted on feral peafowl outside their native range, so it isn't unreasonable to suggest that the physical environment has influenced the peafowls' behavior.-----In combination, these papers indicate that the feather train does play a role in sexual selection, but that role is not as simple as scientists used to think, and we do not really know what that role is yet.The story is not complete. But then, in science, the story never is complete: we're always working to improve our knowledge, and we don't stop trying to improve our knowledge when one study raises difficult or uncomfortable questions.This is a fantastic find, Arriba, and one that will certainly lead to important improvements on our understanding of how nature works.-----I would like to pose one question to you: how do you explain how peacocks survive with a handicap like that feather train? The evolutionary explanation is that it provides some benefit that outweighs the disadvantage. We do not know what that benefit is, but, based on the Theory of Evolution, I predict that such a benefit does exist and will eventually be found. What alternative prediction do you propose, so we can test our competing hypotheses?Edited by Blue Jay, : Rewording.

Yes, I certainly agree that this could happen: cheating, lying and stealing are viable and often successful strategies in the wild, just as they are in human society.Of course, as the theory of sexual selection goes, certain traits indicate fitness precisely because unfit individuals can't replicate them, but I'm not well-read enough on the relevant literature to determine how prevalent a "faker" phenomenon might be. You seem to be aware of some examples: I would definitely be interested in reading them, if you were willing to share them.But, if we consider the possibility of "faker" peacocks, then wouldn't this potentially explain why the feather-train is only weakly correlated with female preferences? Perhaps the feather-train only establishes a baseline filter for fitness, and the females are capable of scrutinizing other factors to separate "fakers" from genuinely fit males. The studies I cited upthread all seem to mesh well with this hypothesis, so would you be interested in applying for some funding to test that hypothesis with a little bit of research? Do you think the Discovery Institute would fund an opportunity to disprove a Neo-Darwinian sexual selection theory?-----If you were claiming that sexual selection is invoked too often in biology research, I would agree: every hypothesis is invoked by researchers in more cases than it actually applies to. But, science is a trial-and-error process: there is no way to be confident that you've correctly developed or applied a hypothesis until a significant amount of research has been done. So, it's no surprise that we're wrong a lot.-----And, finally, I pose the same question to you that I posed to Arriba: How do you propose that peacocks with feather trains survive in spite of the apparent handicap of giant feather trains?-----P.S. You'll notice that I put a space in my name now: without the space, it's apparently slang for something that I'd rather not use as my screen name.

Hi, Petrophysics. Since you made it personal by inserting my name into your examples, I am obligated to state that neither case is very much like reality, because, in reality, Blue Jay is in a happy and monogamous relationship with a beautiful woman, and would not have sex with any of the women you described in your silly examples. Okay, now that the silliness is aside, let's examine the scenario. Both cases are, in principle, the same: you allowed a subject to choose from a range of potential mates, and the subject selected the "best" of the options presented. As such, I think they both match reality equally well.You might understand it better if you treated the females in your examples as active participants, rather than objects to be selected. You see, for a female, the investment into reproduction is typically higher than for males, so the consequences of poor choices are also higher. That means there is more reason for sexual selection to favor choosy females than to favor choosy males.

Reality check. Here are "profile" pages for four female chimpanzees at a sanctuary in Uganda: CindyBeckyKatieMeganNotice anything relevant to this conversation in those photos? Hint: Beards. And moustaches.----- Any story that fits the available evidence would serve as a good hypothesis, yes.So, if men routinely preferred beefy women with big noses over dainty women with little noses, then you could very well hypothesize that sexual selection has favored beefiness and big noses. But, since that's not the case, you probably shouldn't hypothesize that.In the same vein, if peahens preferred to mate with males who had their feather-trains cut, then you could hypothesize that sexual selection does not explain why males have big feather-trains. But, since that's clearly not the case, I'm uncertain why you would hypothesize that.

Hi, Bolder-dash.We may be getting a bit far from the topic, but I think this conversation is still related, so I'll pursue it a little further. But, this isn't the point I was trying to refute. Your original point was: Now, your point seems to have changed into "None of them have facial hair that looks like a human's beard if they haven't shaved for 15 years."If your point is that chimpanzee beards are different from human beards, then say, "chimpanzee beards are different from human beards"; and don't say, "chimpanzees don't have facial hair."But, even if your point was that chimpanzee beards are different from human beards, I still think you're wrong: those chimpanzee beards look a whole lot like human beards to me, and I do see mustaches (admittedly, not very dense mustaches; but there is hair on their upper lips).It's true enough that your photos of human men had much longer beards and much thicker mustaches than these chimpanzees have. But, I wasn't arguing that females chimpanzees had more facial hair than human men do: I was pointing out that female chimpanzees have beards. And so do female orangutans and female gorillas.Remember when you were completely incredulous about RAZD's idea that human "hairlessness" is due to sexual selection? This is what you said: And, you were right: RAZD was suggesting that there was a time when all the females had significant facial hair. This is supported by the observation that, in all of the purported close ancestors of the human species, females do, in fact, have significant facial hair.If I didn't know better, I would think RAZD was actually selecting the fairy tales he believes in based on how well they fit with available evidence. What kind of asshole chooses his fantasies that way?Edited by Blue Jay, : My links to the orangutan and gorilla photos were screwed up.

Hi, Arriba. "Regression to the mean" is a phrase I'd heard before, but I never knew what it was. I spent a little time pottering around on the internet, trying to understand the idea. I'm still not sure I understand it, but the it seems to be only marginally more substantive than the claim that the "gold-standard" p-value of 0.05 isn't sufficiently stringent to prevent false positives: I don't see how it amounts to the grandiose condemnations of the entire biological sciences that you believe it to be.----- Well, no, it wasn't a smaller effect size that they reported: it was the scale at which the difference was important. What they reported was that there is a natural range in certain feather-train characteristics, and females don't discriminate between these natural values. But, if feather-train characteristics deviate outside that typical range, females do discriminate.----- If all you can do is appeal to your own ignorance, then you have nothing to offer: should the need arise to appeal to ignorance, we already have plenty of our own lying around to appeal to. Nor are we afraid to admit it.No, fear of the unknown isn't what distinguishes us: we both have admitted that we don't know what's going on with the peacock feather-train, and neither of us seems to be on the verge of a major life crisis because of it. Where we differ is in our prognosis for the state of our knowledge in the future.Your position seems to be that ignorance is perfectly acceptable as a long-term strategy. Basically, not only do you not know, but you have no intention of even trying to find out. And, that's perfectly fine: there's no particular reason why you should have to know what peacock feather-trains are for.But, several researchers would much prefer to alleviate their ignorance. So, they are using the current understanding of the world and currently-accepted "best-practice" reasoning to try to learn more about peacock feather-trains, and are hoping that, in the process, they might even help improve on our current understanding and on our "best practices."You claim to have discovered fundamental flaws in both our current understanding of the world and in our currently accepted "best practices." But, as usual, you provide no alternative ideas that are demonstrably better. Until somebody can find a hypothesis that is clearly "right," all we can really do is try to decide which of our current hypotheses is "least wrong."-----So, let me ask you again: why do peacocks have long feather-trains? And, how do they manage to persist when they have such an apparent handicap?

Hi, Bolder-dash. Forgive me if this gets too personal and too far off-topic, but I'll be damned if I'm going to let you jerk me around in a debate like you clearly want to.You make far too many points and spend far too little time elaborating on each one. So, I make no attempt to engage them all. For example, you managed to squeeze four distinct topics into the 109 words of the post I am currently responding to:

1. Male chimpanzee sexual preferences
2. Adaptive value of mustaches
3. Variable neoteny in human females
4. Pro-evolution bias in science

This is a classical "Gish gallop." You make too many points for me to answer, and when I pass over some of them, you accuse me (and, in this case, all my colleagues) of intellectual dishonesty. In this case, you are also using it to deflect attention away from the comically wrong claim you made about chimpanzee facial hair.Well, guess what? You were wrong: female chimpanzees have beards. I have presented photographic evidence of this. If you will clearly concede that you were wrong on this point, then I will proceed to engage the rest of your argument.Edited by Blue Jay, : As much as I disagree with a person, I feel it a basic act of decency to spell his name correctly

Hi, Bolder-dash.Again, I am fully willing to move on to the next phase in our discussion, but if you are unwilling to concede a simple point about whether or not female apes have beards, then what guarantee do I have that the discussion won't just become recursive the next time I mention ape beards?You'll notice that, upthread, Larni was able to admit that his claim ran afoul of photographic evidence, despite his pro-evolution bias. You wish to have a discussion about "bad science biases"; but your case is hopelessly lost if you cannot even match the level of intellectual honesty your audience can clearly see in your opposition.

Hi, Arriba. I'm flattered that I come off as so worthy of responding to! I feel that you've come to this conclusion in error, but I have lots of dissertation writing to procrastinate, so I won't complain. I am personally in great need of remedial math classes, and will consequently not make much effort to challenge you mathematically, despite not knowing what your credentials are. But, I happen to know that the poster you're referring to has advanced credentials in mathematics, so, due to my current biases, I am inclined to think that his post was not made in ignorance.----- This is common knowledge. But, from my perspective, you are making claims about certainty, while nobody else is. I support the sexual-selection hypothesis, not because I am certain that it is correct, but because I have yet to see any alternative hypothesis that explains the evidence as well as sexual selection does.----- Okay, I am not very knowledgeable about math or statistics, but you clearly didn't do any Bayesian statistics there: you just used the prior probability, instead of attempting to infer a posterior probability, which would have improved on your estimate and given you the ability to attach an uncertainty to it. All you actually did was name-drop Bayes and then pretend that math backs up your questionable decision to define your level of skepticism arbitrarily.I arbitrarily decide on an a priori probability one order of magnitude higher, and am therefore only 9.153% skeptical. Actually, I think we technically only get one significant figure, so I'm just 9% skeptical.----- Here are some flaws in your argument:

1. Your mathematical "proof" is based on a couple of assumptions, which means it's not a "proof," but a "model."
2. The arbitrariness of your assumption calls into question the validity of your comparison with coin-flipping.
3. You did not attempt to account for the uncertainty associated with the inference from your model, so you cannot even state that your 8.47% likelihood differs significantly from the 50% a coin-flip would yield.
4. Neither you nor anybody else has quantified how well proponents of science claim that science works, so you can't have "clearly shown" anything relative to that value.
5. Also, you cited a single blog post, not "numerous non-replicated studies."

If your argument is so full of holes that a mathematical dunce like Blue Jay can tear it apart, then perhaps you should reconsider your absolutist stance on "flawed methodologies."----- Well, if I had an alternative idea that is demonstrably better, I think I would respond by showing it to him. But, who knows? Ever since you showed me how flawed empirical hypothesis-testing is, I can only be approximately 8% confident that my current hypothesis of my own personality is accurate, so we might as well flip a coin to determine how I might respond.If, on the other hand, I have no alternative ideas that work better, what, exactly, could I say to him? "Um... maybe you could try something else that doesn't work?" Would that convince you to change your ways?----- Indeed.I am unclear where this tirade on truth came from. I have no trouble accepting that scientific conclusions come with rather large uncertainties, or that they are consequently wrong with very high regularity: what I have trouble with is that you seem to want us to stop doing science, but don't have any real insights into what we could do instead to avoid our current quandary.I can only conclude that you are recommending that we give up trying to learn things. I cannot see how that would be an improvement on our current situation, but perhaps you could show me.----- Your arbitrarily-inflated skepticism has turned you into quite the cynic. I hope you at least believe that we are clever enough to have concluded that participating anonymously in this debate is highly unlikely to have positive influences on either our sex lives or our status in the scientific community.

Hi, Bolder-dash. I'm not trying to monkey around: I'm trying to understand why photographic evidence that appears very clear to me does not seem clear to you.Can you please describe exactly how chimpanzee beards differ from human beards? I honestly don't see what it is about their beards that makes you think they're so vastly different that they don't have any meaning to this discussion.Also, I screwed up some "url" codes in my earlier post, but I have now fixed the problems that ruined my links to a female orangutan and a female gorilla. Orangutan beards are particularly interesting. I certainly can't deny the "bumbling" thing: we are, after all, relying on our meager human faculties to try to make sense of the wonders of the universe, so the fact that we suck at it isn't itself a very meaningful criticism. Science bumbles along like a toddler learning to walk; but, as I've been trying to explain to Arriba, there's really nothing for it: all we can do is keep bumbling around and do our best to learn from it as we go.If you know of a better way to figure out what a peacock's feather-train is for, please enlighten us. And, if all you have is "turn to Jesus" or "read the Bible," then, surely one of you who has already turned to Jesus should already know what a peacock's feather-train is for. But, since neither of you is willing to answer this question, we can only assume that turning to Jesus hasn't magically imparted this knowledge on you, either. And so, we choose to continue bumbling, because, even though it's difficult and inefficient, bumbling can potentially get us a useful answer. I agree. As you rightly stated, the number of handicaps and hardships an organism can survive is very large, and there are a very large number of viable strategies for survival. But, as you have consistently failed to grasp, our paradigm is not "survival-only": our paradigm includes many separate processes of selection, some of which have very little, if anything, to do with "survival" at all.Survival is a bare minimum standard of fitness. If you survive famines, parasites, predators, injuries, birth defects and natural disasters, but do not leave any offspring, your genes do not contribute to the future gene pool, and so, in evolutionary terms, you are a "failure," or a "dead end."So, clearly, there should be selection for more than just basic "survival": there should be selection for things with little relevance to survival, but relevance to other metrics of success. There should be selection for anything that improves an organism's chances for successful reproduction. In fact, if the Theory of Evolution is correct, then successful reproduction, and not survival, is the "gold standard," so we should expect to see many examples of organisms whose drive to reproduce outweighs their drive to survive.That's where we come up with the conundrum of the peacock. The feather-train is clearly a liability for the peacock, and surely it would be easier to survive without it. Why would an animal have such a trait; and how is it that they continue to thrive, despite having this unnecessary liability?I would like to hear your ideas on this. I think the feather-train somehow increases the peacock's chances of successful reproduction, even though I don't know how.But, what do you think?
Do you think that peacocks simply suffer insignificant levels of predation, and thus the actual, realized liability is quite low?
Do you think God somehow designed the Indian ecosystem such that long feather-trains are not a liability?----- I don't deny that it's a confused mess. But, given that there are no universal principles that force animals (or humans) to behave in clear, consistent, perfectly rational patterns, what else would you expect? Why would expect perfectly consistent behavior in such a complex system?For example, for humans, women with large breasts and wide hips are considered attractive; but, a long, slender stomach is also considered attractive. So, "idealized" women in fiction frequently have both (e.g., Jessica Rabbit, Betty Boop, Barbie, etc.), which seems like an architecturally unsound arrangement.How do you explain this sort of behavior, except under a context of inconsistent, contradictory signals?

Hi, Arriba. I don't understand where you came up with this 10/100,000 figure: it seems like is was a figure specific the schizophrenia-gene-polymorphisms example, so I'm not clear on how those odds are relevant to our current discussion. No, actually what I didn't notice is that your math formula was Bayes' theorem: it was a math equation, so my eyes just glazed over when I came to it. My apologies for my failure, and for my subsequent sarcasm about it. I have reason to contest several of these reasons:Reason 3: Peacocks from both groups were handled in the same fashion (minus the clipped feathers), so we can almost certainly rule this one out (or at least weight it very low).
Reason 4: This still suggests that females select mates based on feather-train attributes, doesn't it?
Reason 5: You're slicing your hypotheses really thin here; I see no reason no distinguish this from Reason 1.So, the way I see it, you only really have 2 possible explanations, or 3 if you let Reason 4 stand. I'm a little confused as to what you think you're doing here. Aren't you just using the principle of insufficient reasoning to do the same thing that you already did with Bayes' theorem, i.e., estimate P(H|E)?

Hi, Arriba. Again, the control group was captured. The study began with 11 experimental males and 11 control males. Most of the control males did not lek or mate, so they included data from males outside of the original study design to serve as additional controls. These males were not captured over the winter, but they had been captured in previous winters, and the data collected over those previous years showed that capture during the winter had no effect on mating success in the subsequent mating season. Dakin's group also included a meta-analysis of all studies done on eyespot number in feral peafowl populations. In this analysis, it was concluded that natural variation in eyespot number had no impact on female preference; but, deviation from the natural range in eyespot number did impact female preference.Interestingly, the natural range of variation seems to be largely due to damage, rather than to genetics. So, selection on that scale would not be meaningful for evolution, anyway. You mean you haven't even read the papers yet!?I have access to all the articles listed via institutional subscriptions, and I've read them all except Petrie's rebuttal. Good grief! I didn't realize I was so desperate to procrastinate writing my dissertation! Now I feel guilty.Did you at least read Takahashi et al. (2008), before lauding it as a grand refutation of Darwin's peacock hypothesis? Petrie is listed as the second of four authors on that manuscript. In my experience, that means she was neither the mastermind (last author) nor the actual writer (first author) of the paper, but an invited co-author. But, maybe bird people do that differently from bug people.Still, you're reading too much into it, which is a bad sign.
Admittedly, my choice of procrastination fodder might also be a bad sign, so perhaps it's time for me to drop it and get back to my work.

Hi, Arriba. The vast majority of points you might ever want to make can be made effectively without referring to Nazis. You should really read the papers: this is not, in any way, analogous to the feather-clipping these peacock researchers did. What they did is clip off the 20 outermost eyespots.See, the feathers of a peacock train overlap one another. So, you can cut the eyespots off a feather without leaving a gaping hole in the peacock's train, because the neighboring feathers overlap it. And, because the eyespots are never on the outermost edge of the feather-train, the "damage" only manifests as a gap between the feather-train edge and the outermost eyespots.As you can from the photos below, that gap varies quite a lot naturally:Page not found – Macaulay Library
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If a Peacock Loses His Tail Feathers, Do They Grow Back? | HowStuffWorks
Files - Wikimedia Commonseacock_Dance.jpgSo, clipping a peacock's feathers doesn't make them look "mutilated": it makes them look like a peacock with a smaller feather-train.By comparison, amputating a nose doesn't make somebody look like someone with a small nose: it makes them look like somebody with a gaping open wound instead of a nose. There are no rules about how you come up with a hypothesis. You just have to come up with predictions that arise from it, and with a way to test those predictions. Einstein came up with the prediction, and some other physicists tested them.Science.Edited by Blue Jay, : Disable smilies so my photo links would work