ThoughtStorms Wiki

Review of a book criticising adaptionism :

The problem is, without adaptionism, evolutionary biology is about as exciting as rote-learning the names and dates of the kings and queens of England : "And then Richard was replaced by Henry. And then the leopard got it's spots."

I believe that Adaptionism is what makes evolutionary biology a science rather than a laundry-list of changes that happened. It's the thing that lets us make cross-species and cross-time comparisons. I'd go further and argue that teleology is the only thing that allows any kind of history to be a science in an interesting way.

To be clear, it's not that there isn't science in biology without teleology. There's plenty of chemistry and mechanics to be done. We can look at proximal causes and constraints on the growth of certain protruberances from the body. We can study the mechanics of how muscles work and why bones don't break and the weight of the body.

But to give any meaning to it. To give this bundle of mechanical and chemical systems any kind of semantics, you have to introduce function. We have to refer to what the organs are and what they're for. The same is true for any system in the body. And, more relevantly to this discussion, any behaviour the animal displays.

It's this talk of purpose that makes sense of different situations throughout history and lets us make comparisons between species and times. When we think of two behaviours as "parenting" or "parasitism" or "agressive signalling" we can compare them as examples of the same class of phenomena when we encounter them in different species. Without such classes defined by purposeful talk, we have very little : we can say that the animal moves, and that's that.

This need for function equally occurs when we want to investigate the kind of meaningful causality in history that opponents of adaptionism want to highlight. Because causality at the grand scale in biology is precisely the causality of systems adapting to the constraints on them, and opportunities afforded to them, by their environment.

Now, that isn't to say we can't recognize constraints due to physics, chemistry or historical canalization. And no adaptionist seriously suggests we ignore such constraints or thinks that the nature has a blank slate to draw on. In fact, much interesting work in evolutionary research concerns exactly the dynamics of adaption and the sequences and orders which adaptions happen. And when the anti-adaptionists are pointing out some interesting cases of constraints or dynamic patterns, this is very interesting.

But there's no sense that this offers an alternative research strategy. A strategy devoid of adaption and purpose would see evolution as a chapter of accidents without sense or meaning.

Of course, there are plenty of adaptionist hypotheses that are wrong. But there are plenty of causal hypotheses that are wrong too. Being able to make wrong hypotheses isn't a sympom of weakness in a scientific framework, it's a sign of expressivity.

From what I read the book is critisizing 'extreme adaptionism' for it's oversimplification, not the whole adaptionism argument.


Just noticed this quote from Wilson and Sober :

One of the virtues of the adaptationist program is that it can be employed with minimal knowledge of the physiological,biochemical and genetic processes that make up the organisms under examination. For example, imagine studying the evolutionary effects of predation on snails, seeds and beetles. Suppose you discover that for all three groups, species exposed to heavy predation have harder and thicker exteriors than species not so exposed. The property "hard exterior" can be predicted from knowledge of the selection pressures operating on the populations. Since the exteriors of snails, beetles, and seeds are made of completely different materials, there is a sense in which these materials are irrelevant to the prediction (Campbell 1974, Wilson 1988). That is why Darwin was able to achieve his fundamental insights in almost total ignorance of the mechanistic processes that make up organisms. Adaptationist explanations have the power to unify phenomena that are physiologically, biochemically and genetically quite different .


Adaptation brings in function which brings in MultipleRealizability

I read this some time ago, but I'd forgotten it. But must clearly have been an influence on my thinking about adaptionism.


See also :

CategoryBiology, CategoryEvolution, CategoryArtificialLife, CategoryFunction, CategoryScience