Monday, May 19, 2008

Peacock's Trail

It might be suggested, in a somewhat violent image, that nothing had happened in that fold or crack in the great gray hills except that the whole universe had been turned inside out. I mean that all the eyes of wonder and worship which had been turned outwards to the largest thing were now. turned inward to the smallest. The very image will suggest all that multitudinous marvel of converging eyes that makes so much of the colored Catholic imagery like a peacock's tail. (GK Chesterton, the Everlasting Man)

The cock stopped suddenly and curving his neck backwards, he raised his tail and spread it with a shimmering timbrous noise. Tiers of small pregnant suns floated in a green-gold haze over his head. Flannery O'Connor.

You probably already know of our family fondness for peacocks. Liam photographs them at his college, and has written one into a story he is working on. When I am talking to him on the phone on Sunday afternoons, while he strolls in the meadows below his campus, often the conversation is punctuated by comments like:

There's one up on the roof!
The others are looking up at it. They look concerned.
It looks concerned, too.
Now it's flying down.

Then you hear the background pea-chicken chorus that Flannery O'Connor transcribed like this:

Lee-yon, lee-yon,
Mee-yon, mee-yon!
Ee-e-oy ee-e-oy!
Ee-e-oy ee-e-oy!

She calls it a "chorus of jubilation" but filtered through a cell phone they always sound like cats yowling plaintively, to me.

For Flannery O'Connor they evoked mystery and manners. When I talked to the Dominican priest who lives near the peacocks on the campus, he told me that they like to perch on his roof and sometimes early in the morning, just as he is waking up, he hears them run heavily down the roof to land on the ground. The combination of respect for mystery and pained admiration for manners in his voice was quite indescribable.

I read in Stanley Jaki's book Savior of Science that Darwin wrote in a letter to a friend, Asa Grey:

"...and now trifling particulars of structure often make me very uncomfortable. The sight of a feather in a peacock's tail, whenever I gaze at it, makes me sick!"

This struck me quite forcibly, that his reaction was so different from the wonder and amusement that these pheasant-folk inspire in my children, one of my favorite writers, and the priest acquaintance.

I went on a "peacock trail" online and found this much more appreciative passage in Darwin's Descent of Man:

The Argus pheasant does not possess brilliant colours, so that his success in love appears to depend on the great size of his plumes, and on the elaboration of the most elegant patterns. Many will declare that it is utterly incredible that a female bird should be able to appreciate fine shading and exquisite patterns, It is undoubtedly a marvellous fact that she should possess this almost human degree of taste. He who thinks that he can safely gauge the discrimination and taste of the lower animals may deny that the female Argus pheasant can appreciate such refined beauty; but he will then be compelled to admit that the extraordinary attitudes assumed by the male during the act of courtship, by which the wonderful beauty of his plumage is fully displayed, are purposeless; and this is a conclusion which I for one will never admit.

While I was looking for more thoughts upon peacocks and evolution, I found this site called The Third Evolutionary Synthesis. It's interesting because it contains all sorts of evolution-related material, including some critiques. I haven't looked enough to see whether it is weird marginal stuff or not. More central to my topic are the peacock feathers on the page's banner and these postscripts of the review of Johnson's Darwin on Trial.

In the postscripts, the webmaster mentions that Johnson critiqued Darwin's views on peacocks and sexual selection.

(Quoting Johnson)"what I find intriguing is that Darwinists are not troubled by the unfitness of the peahen's sexual taste. Why would natural selection, which supposedly formed all birds from lowly predessors, produce a species whose females lust for males with life-threatening decorations?" (p.30).

Biologists now have good explanations for the peacock's tail. It is called the handicap principle. It is beautifully and accessibly described in a book by A. and A Zahavi(1997,1999) 'The Handicap Principle - A Missing Piece of Darwin's Puzzle'. In short: the long tails of male birds reliably demonstrate to females that those males are healthy and can afford such handicap. It can only be a reliable signal when it is a handicap. Females prefer strong males because they produce healthy children.
The Handicap Principle -- hey, there is another peacock tail on the cover!

Some people apparently don't think the handicap principle explains things sufficiently. I followed the trail a bit further and found this book, displaying another peacock-tail decor on its cover: Darwin Misread Miss Peacock's Mind.

It apparently makes the case that the handicap principle or Darwin's aesthetic appreciation explanation is too much like anthropomorphism:

But beyond this, many present-day students still maintain that at least part of the explanation for the origin of fancy males involves female choice. In support of this, some authors resort to many highly convoluted anthropomorphic interpretations that outdo even those of Darwin. Birds are seen as possessing a knowledge of population genetics in near mystical proportions. The female can evaluate the "fitness genes" of a male on the basis of intricate plumage designs, following a principle of "handicaps."

Mr. Darwin Misread Miss Peacock's Mind develops the idea that attraction of a female to a male warrants a straightforward stimulus-response interpretation. The female is driven by response to a food stimulus. The food may be found in the territory of the male or may be pictorially represented on the plumage of the male. The female obeys the laws of plain, old-fashioned home economics! Courtship-feeding is seen as a method of bringing together creatures of similar tastes and physiologies. The ensuing mate selection results in genetic specialization to differing food niches, finally resulting in species formation.

Hmm, that seems stretched to me. Home economics? Isn't that anthropomorphizing a bit too?

A National Geographic article puts forth another explanation in: How Did the Peacock Get His Tail?

A study published earlier this year in the journal Behavioural Ecology shows that a male's plumage is a direct indicator of the strength of his immune system; a signal to females of his internal workings.
It goes on to say that showy feathering may show lack of parasitical infestation, a survival trait that will be passed on to Mrs. Peacock's sons and daughters. However, the article goes on to say that the evidence on this is inconclusive. Infested peacocks often continue to have showy plumage to the very end stages.

This post on Peacock's Feathers: Darwin's Nightmare has some spectacular pictures of albino peacocks, and makes the point that things like feathers and eyes seem to be "irreducible" -- it is difficult to even imagine them evolving in stages.

The peacock's tail remains a mystery even after it is analyzed, and a related but even more mysterious thing is the paradoxical power of the brown peahen. Even more mysterious and paradoxical is the power of that"galaxy of gazing, haloed suns" has for a human mind, not leastly Darwin's.

1 comment:

Anonymous said...

Sometimes ID reminds of the time I was reading the A Beka science book for 3rd grade (we were attempting to do MODG's 3rd grade that year). The book is very appealing. Lots of beautiful photos. Anyway we were in the chapter about the ocean and it was going on in a scientific vein about the water cycle, etc. Then it got to the question of why the oceans are salty and the text said, "because God made it so."

Huh? Did God make the water cycle too? Yet we got to discover how and why that works, why can't we inquire into why seas are salty? To me that illustrated the inappropriate mix of theology and science. The appropriate mix, for me, is to assume God underwrites everything and science is there to discover how He did it. Science is for discovering nature, theology is there for discovering the supernatural.

I think the mystery of the Peacock's feathers is quite fascinating!