Or, "Charles Darwin Lied."* Part one of an at-least-three-part series.
Calvin has a hairier face than most.First, a disclaimer: while I have a modest background in science, that science is not biology, and I am by no means an expert in these matters.
(1) There are a whole host of aspects to life that, while wonderfully aesthetic, imply no obvious reproductive advantage. One can still attempt to explain them through the framework of natural selection and random mutation, and indeed many do attempt so, but these attempts often strike me as strained, and are circular themselves inasmuch they seek to offer evidence for evolution.
A few examples:
- Forgive me for allowing most of the details to escape me, but I remember reading several years ago about a prize awarded to a man for thinking of an explanation for why people aren't nearly as hairy as other apes.
His prize-worthy idea? Perhaps mothers preferred babies who were less hairy and were thus more likely to care for them.
That's it.
My problem with this reasoning is that it could be used to justify any trait unique to humans. Who knows what would be possible if our great-grandmothers had different tastes! Perhaps we would all be able to sing "Do your ears hang low?" with much more gusto. Perhaps Chewbacca would exist in reality and not in myth. - The peacock's tail is a prime example of what is called "sexual selection:" the trait makes the peacock no more fit physically, indeed less so, but nevertheless makes him more fit in the evolutionary sense because peahens are impressed by peacocks with more impressive tails. The tails are said to signal fitness, perhaps because the man is able to survive despite the handicap.
The logic strikes me as just a bit twisted. He proves he has good genes by surviving despite having bad genes (which give him a functionally useless display of feathers).
(And why should peahens prefer mates with more impressive tails to begin with? Would this trait itself not have to evolve?)
Another challenge is presented by the knowledge that it seems peahen mate selection is rather independent of peacock tail impressiveness. For the evolutionary argument to hold up in light of this knowledge, peahen preference toward impressive tails must have evolved some time ago, then evolved away again after the men had gone through all the effort of evolving their tails. Women are so hard to please.
Consider, for a moment, an alternative explanation: Peacock tails are beautiful, and this fact has something to do with their origin.** - As a final example, consider breasts in women, a topic upon which my male readers should have no trouble focusing. Believe it or not, their presence presents a significant challenge to evolutionary theorists.
The story is similar to the puzzle of why we aren't so hairy. Put simply, most female mammals develop breasts only after giving birth, and their breasts remain only while nursing. Only in human women do they develop first and for always at adolescence, then further around the time of birth. Breasts in other mammals are decidedly unattractive to males, since they signal that the female is not in much of a state to bear young.
Why should this be so? There are evolutionary ideas. Perhaps breasts evolved so that babies would have an easier time nursing. I think it was Stephen Jay Gould who posited that they developed so men would have an easier time getting used to mating face-to-face (which raises the question of why people evolved the propensity to mate face-to-face). Evidently, our great-grandfathers much preferred their wives' posteriors to their faces. Men are so insensitive.
But these ideas are just speculation. In short, there is no good reason why this trait ought to evolve, from a Darwinian perspective. One can posit, "There must have been a good reason, because this trait clearly evolved!" But that is circular reasoning and placing faith in Nothing.
And so I say, only one third in jest, is it not evident that breasts are a great gift from God to men, women, and babies alike?"I made you flourish like a plant of the field. And you grew up and became tall and arrived at full adornment..." (Ezekiel 16:7a).
In short, the world is full of incredible beauty, and this beauty is very difficult to explain with a framework that only rewards survival, like a society of Van Goghs which cares nothing for its artists.
Rather, it is evident to me that many things are beautiful because they were made with beauty in mind.**
*Not especially true, as there is a world of difference between lying and simply being mistaken. But it goes well with another recent post of mine.
**This, of course, requires that beauty exists in an intrinsic, objective sense.***
***This, of course, requires that there exist someone with the authority to set such a standard. You can see where I'm going...
7 comments:
Although I'm sympathetic to your position, I find the fossil and genetic evidence for evolution pretty compelling. However, you have a good point about sexual selection arguments. They don't seem to work too well.
Incidentally, do you consider evolution irreconcilable with Christianity?
Maybe peahens have bad eyes?
Jonathan - Well, the fossil and genetic evidence would seem to present a succession of increasingly complex species, which is not inconsistent with an evolutionary narrative. However, an evolutionary narrative is not the only narrative with which it is not inconsistent.
I would say some aspects of the fossil record seem quite inconsistent with an evolutionary perspective, which depends on gradual, slight change over very long periods of time. The most striking example is the Cambrian Explosion, where all of the animal phyla alive today (and a good many that aren't) appear in a geologic blink of an eye.
Evolutionary theorists respond with "punctuated equilibrium," saying evolution happens rarely but rapidly. My understanding of this idea is that it presupposes evolution in order to explain evolution in light of the fossil record. In other words, bunk. I am aware of no mechanism by which natural selection and random mutation could do their magic on these time scales.
As for your second question, I'd like to think that I reject the theory of evolution on its own merits, not because my Bible requires me to. I don't find it necessarily irreconcilable with Christianity (though I have a problem with humans coming from apes), but as you can see in my post, I think it casts a disparaging light on the considerable portion of reality it fails to explain (i.e. beauty; the reduction of altruism to self-interest).
In addition, evolution provides many the great escape from God for which they search. Before it, no one had offered a plausible-sounding atheistic explanation for humanity's origin. It more than anything else allows atheists to purport to have the intellectual high ground.
So, irreconcilable? No. In its ground state, at odds? I think so.
Nick,
I think you are mistaking what fitness actually means. You talk about physical fitness separate from fitness "in the evolutionary sense," and tie it into survival.
Fitness actually has a specific meaning when talking about evolution. It is, simply, how well you pass on your genes. In other words, it's your ability to have successful offspring. So, survival really doesn't have much to do with it (a man who dies at twenty but fathers 3 children is considered more fit than a man who dies at 90 - i.e. survived longer - but only had 1 child). Of course, if you don't survive to child-bearing age, than you aren't fit at all, so they aren't entirely divorced.
Using your peacock sexual selection example, it's not that the tail signals fitness because the peacock was able to survive with such a cumbersome tail. The only factor in fitness is offspring, not survival. There's also the concept of the "Sexy Son." A female will choose a mate to maximize her fitness - the idea is that the female chooses a male whose sons will also have the desirable trait (nice big peacock tail), meaning that female's genes are more likely to be passed along. I don't necessarily buy it, but it is a concept within evolution.
Finally, for your breast example, I haven't given much thought about the evolution of female breasts, but their main purpose (arguably) is to provide milk to their children. It would be desirable, then, to have more/bigger glands, which would require bigger breasts. In the evolutionary sense, then, breast size might indicate the capability of the mother to nurture offspring.
Also, I'd like to know where it was shown that peahen selection was independent of peacock impressiveness. That certainly sounds interesting
Nick,
You may be correct that the fossil and genetic evidence is less strong than I understand it to be. I'm certainly no expert on the matter. However, my understanding is that the following facts hold:
(1) Evolutionary theory makes strong predictions about the rate of genetic drift and speciation as a function of time.
(2) Observed genetic differences among modern species correspond to the dates of divergence suggested by the fossil record.
(3) Observed genetic differences among modern species correspond to dates of divergence implied by geographic distance. (For instance, bird species on island A are genetically closer to bird species on nearby island B than to birds on the mainland.)
I find these facts pretty compelling.
Pat - I was aware of the proper definition of fitness. However, your comment made me realize my reasoning included an assumption that doesn't necessarily follow.
My assumption was that the peahen's preference would be related to physical fitness - that she prefers a larger tail because it would be indicative of a man who was stronger in other ways.
You could say the preference is unrelated to physical fitness, perhaps to the peahen's own aesthetic preference. But that seems like it would be detrimental to the survival of the peacock species as a whole, and would be selected against.
In that case, you're still saying the peacock has his tail because it's beautiful. The difference is in the beholder.
Yes, I should have posted my source for saying that peahens don't actually seem to prefer males with more impressive tails. I'm going pretty solely off this blog post.
If I understand what you're saying about breasts (and please correct me if I do not), you suppose that larger breasts could signal a higher capability to nurture young, and thus have a good reason to be preferred by men. Well, my understanding is that milk production capacity is rather independent of breast size - that smaller-breasted women can give just as much milk, without dealing with back problems or other potential hangups of larger breasts.
My point is simply, if all breasts re for is nursing, then the way other mammals do it makes the most sense, and there's no reason why humans should evolve something different.
It seems to me that evolution requires everything to be functional; if it doesn't aid in procreation, then it should be left behind. But there is a great deal that exists and yet is not functional in this kind of way. And I am very glad that many of these things exist.
For an excellent talk that highlights many aspects of human sexuality which appear to be gifts rather than adaptations, listen here.
Jonathan - Wow, I have heard almost nothing of those facts. I'd be interested to read more. They would indeed seem to be strong empirical evidence for evolution.
Perhaps an important thing to keep in mind is that genes are far from the whole story when it comes to an organism. Note the oft-cited statistic that chimpanzees share an absurd percentage of our DNA. While the genomes may be nearly identical, it's clear in the final product that we are much more than 1.5% different than chimps.
As I understand, the human genome project has been a bit of a failure because of the simple fact that one gene can code for more than one protein - in other words, genes do not map a function to proteins.
I've read that to fully understand life we would need to sequence the proteome, a task which at present is far beyond our capabilities.
I say this only to indicate some mild skepticism of genetic drift as a direct indicator of speciation.
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