Sculpting Species

Today on Facebook, someone posted the comment: "nothing evolution designs is rational." This got me to thinking along the following lines. I'm not so sure that statement is true. I don't mean to turn this into a word game by twisting definitions to suit my purpose, but let me try to recast that phrase for purposes of discussion: "because none of the adaptations that have resulted in an increased chance of survival is the result of ???" The result of what? Conscious deliberation? Is that the only thing that can possibly qualify as logical or rational. What about suitability for a particular purpose? Is it a rational or logical outcome if something is repurposed to fill a role that suits its particular nature?

Take feathers, which first appeared on the evolutionary stage as an insulator, a role they're well suited for. But when they chanced to also confer an increased survival advantage by enabling the organism to briefly take to the air, were not their particular properties really being put to a use even more striking than insulation? I think one could argue that it is a rational use of the feather to enlist it in the task of flying.

To design is a deliberate act. It is natural and easy to speak of evolutionary processes in terms that suggest the exercise of a conscious will because organisms so often display such an elegant commingling of form and function. But it is a misleading metaphor and one that contributes to peoples' reluctance to acknowledge its role in speciation. 

I think sculpting is perhaps a more apt analogy for how evolution actually works. We've all seen examples of a block of stone turned into a beautiful statue. No one doubts that these works of art are deliberately created by human artists. But beautiful works of art and magnificent creations can also be created by nothing more than the constant movement of water or air on rock. 

The exigencies of survival exert a similar influence on species of living organisms over time. A tiny random change gives a slight survival advantage to an organism and the genetic code that produced that change is passed on. Later, another tiny random change results in another improvement and is likewise introduced into the species' genome. Other random changes occur that are neutral or harmful to the organism and thus do not confer a survival advantage. Over a very long time and many, many generations, these tiny random changes that pass through the sieve of natural selection gradually accumulate. In invisibly tiny increments they refine the contours of the species, outfitting it ever more perfectly to make a living in its particular ecological niche. 

The reason we know this works is because we have used the principle of exerting selective pressure of our own manufacture, exploiting the gradual accumulation of random mutations to create countless varieties of dogs. All it takes is time and enough genetic variability to give us options.

So to circle back to the original point: I think there is a type of inevitability to evolution. Given a particular set of ecological conditions, species will gradually acquire traits that make them increasingly fit to occupy a particular niche in that ecology. For me, there is a beautiful, but perhaps unconventional rationality in that process.