Journal Topics

Of Butterflies, Peacock Tails and Poppycock

To his credit, Charles Darwin recognized there were instances of extravagant beauty in the living world that could not be explained by his original theory of evolution by natural selection, so in The Descent of Man he developed his theory of sexual selection to fill the explanatory gap. There he argued, in essence, that the butterfly has extravagantly colored wings, the better to attract a mate, reproduce and pass its beauty pageant qualities on to future generations.

Darwin’s theory of sexual selection is brought in to explain problems like the peacock’s tail. While Brad Pitt’s good looks might have no survival-of-the-fittest downside, a peacock’s pride and glory can get him killed. His enormous tail slows him down, making it easier for predators to catch him. So why would nature select for bigger and bigger peacock tails? Because, according to Darwin’s theory of sexual selection, pea hens are attracted to them.

The theory has a superficial plausibility, but a problem emerges if you scrutinize it long enough. Imagine you have a population of pea fowl. Most of the peahens select their mates in the standard natural-selection way—according to how fast the peacocks can take off, by how well they can handle themselves in a fight with other peacocks, that sort of thing. But over a serious of generations a line of peahens develop with a pronounced artistic streak, leading them to start sidling up to peacocks with bigger, brighter tail feathers. So far, so good. We now have peahens selecting for big, bright tail feathers, which presumably will tend to lead to bigger and brighter peacock tails in future generations. But the question is: Why would natural selection prefer these pea hens with their impractical disposition over pea hens with survival-oriented selection criteria? In other words, why would these artistically inclined peahens evolve in the first place? Darwin’s theory of sexual selection doesn’t give us an answer. It moves, rather than solves, the problem of the impractical peacock tail.

Common reason would urge a person to at least consider the possibility that a great artist lay behind the many instances of extravagant beauty that we find in the living world, but for many Darwinists, common reason has been ruled out of court ahead of the evidence.

Questions:

1. Often times the more attractive animal is the healthier, fitter animal. And certainly these animals will generally have an easier time finding mates and reproducing. How is this age-old insight different from what Darwin was claiming with his twin theories of natural selection and sexual selection?

2. Socio-biologist Edward O. Wilson emphasizes that even the works of artistic genius need to be explained in purely evolutionary terms. How might this view transform the way people think about great art, music and literature?

3. The investigative rule known as methodological materialism insists that scientists only consider natural causes for natural phenomena, never intelligent design. Is this more reasonable or less reasonable than being willing to follow the evidence wherever it leads, even if the evidence points to intelligent design?

— Jonathan Witt

Jonathan Witt, Ph.D., is a senior fellow with Discovery Institute’s Center for Science and Culture and co-author of A Meaningful World: How the Arts and Sciences Reveal the Genius of Nature (IVP Academic, 2006) and Intelligent Design Uncensored (IVP Books, 2010).

Listen to Hank Hanegraaff’s interview with Jonathan Witt on the design and genius of nature featured on the September 20, 2011 Bible Answer Man broadcast.

CRI also recommends: Jonathan Witt, “Darwin vs. Beauty: Explaining away the Butterfly,” Christian Research Journal, 34, 5 [2011]: 42-43. (This issue is forthcoming). CRI also offers United States and Canadian residents a 1 year (6 issues) subscription to the Journal for $39.50 US. A 1 year (6 issues) foreign subscription is also available for $79.00 US. Click here to subscribe.