Saturday, January 9, 2010

Evolution and the Pitfalls of Teleological Thinking

Of Pelicans and Purpose

This morning, the Washington Post reported an incident where the Maryland Department of Natural Resources seemingly defied the forces of natural selection by saving pelicans that failed to fly south for the winter. My first reaction was the same as the article's title implied: "What exactly is the purpose of this? It's one thing to protect and rescue animals threatened by humans, but we shouldn't be rescuing animals who themselves fail to adapt". I very quickly thought better of that sentiment. Not out of any great sympathy for the pelicans, mind you. But because I realized that I made two primary mistakes: (1.) I wrote humans out of the evolutionary narrative, and (2.) I assumed that the death of this flock of pelicans was somehow an underlying "purpose" of evolution, such that avoiding that purpose would constitute an unnatural distortion of the natural order of things. I'll start with my second mistake first. This assumption of mine is at it's base a teleological argument - an argument that identifies a purpose or design for which a given thing (in this case natural selection) exists to achieve. I made the mistake of thinking "natural selection is meant to kill off those who will not adapt, so by preventing the fulfillment of this purpose the Department of Natural Resources is somehow violating evolution - or the purpose and design of evolution". This is the wrong way to think about it. Natural selection doesn't exist for any purpose or design. It is simply a description of what occurs. Organisms exist in an environment. If organisms are not adapted to survive in that environment, they will not survive. The organisms that do survive will be better adapted to survive in the environment. That is all natural selection is. It's really a tautology. There is no "purpose" to derive from it, and there is no agency involved either. Therefore, natural selection can't be "violated", simply because an animal that I thought shouldn't have survived ended up surviving.

As for my first mistake, I also wrote human beings out of the evolutionary narrative. I don't want to get too sentimental or hyperbolic, but I think it's safe to say that human beings are the pinnacle of natural selection (at least here on Earth). We've evolved a number of exceptional faculties that have allowed us to be fruitful and multiply; to fill the Earth and subdue it. One of these faculties is compassion, or altruism. We willingly do things for others, and we do so out of an emotional reaction of concern for their plights (sorry Ayn Rand - no thousand page novel or faux-philosophical exposition is going to change that). Moreover, our compassion and altruism is evolutionarily fit. We're not the only organisms to develop this sort of selfless disposition. Ants do as well, in case anyone feels too proud of themselves over the accomplishment. So how is it a "violation of natural selection," if a trait embedded in the human species by natural selection lead us to save a few stray pelicans? This isn't to say that the actions of the Department of Natural Resources don't have consequences. It's simply to say that when we think about those consequences, we need to think about it in a co-evolutionary way. Could the rescue effort hurt the pelican's chances of survival later? Sure. These pelicans have only demonstrated that they are capable of surviving if humans are there to rescue them. If they are allowed to breed with other pelican populations, future generations may be less capable of surviving without human aid. It's perfectly appropriate to identify that as a potential consequence. We just need to be careful when we assign either meaning, intention, or design to it.

Intention and Evolution
A good source for thinking about teleology and evolution is philosopher Daniel Dennett, who works with the philosophy of mind and the philosophy of biology. He is a strong critic of people who impute purpose to natural selection, or any sort of intentionality in evolution (i.e. - statements such as "X evolved Y to accomplish Z"). However, in looking things up for this post I realized that Dennett is more nuanced on these questions than he first appears. This is an interesting response by Dennett to two critics that is especially illuminating. I like this statement especially: "nothing without a great deal of structural and processing complexity could conceivably realize an intentional system of any interest"

His point isn't that intentional adaptation cannot occur, but simply that the natural selection that we have observed to date generally precludes it, and that any intentionality of any interest would have to be ridiculously complex. This raises two questions: one of intelligent design, and another of directed evolution (well, really one question, but I suppose with two actors). Dennett is an atheist, and so you would think he would slam the door on intelligent design. I think this piece is interesting because he actually insists on leaving that door open (i.e. - he refuses to be baited by the critic that demands Dennett "pick a side" on the teleological question). Nevertheless, of course he still expresses serious doubts. Just because he's open to the prospect of intentionality doesn't mean he thinks we've experienced intentional adaptation.

It also gets to the point of directed evolution, since most of the argument deals with issue or purposive adaptation (i.e. - "X evolved Z to accomplish Y"). Again, Dennett essentially rejects this sort of intentionality, but he doesn't entirely reject the possibility of it. This is another area where you better believe humans are going to (and have already) pioneered. We already intentionally evolve our environment. Rather than letting the characteristics of the species change in response to the pressures of the environment, we have changed the environment to better fit the characteristics of our species. That is innovative, but all sorts of organisms do that too. The ability to force your environment to adapt is an evolutionarily fit trait, after all. What is more exciting (and perhaps somewhat chilling) is the prospect that in the future we will direct our own evolution at the genetic level. This is fundamentally eugenics, and it's not something to be taken lightly. But it's also not something to be entirely written off. We have a bad history of eugenics in the past, but that shouldn't prevent us from thinking about directed evolution in the future. When directed evolution matures, perhaps I'll write another blog post about the need to be more open to a teleological perspective on evolution than I had been in the past.

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