intelligent exaptation

At The Hive of Lost Memories, a post on “the evolution of grocery bags” provides a superb example of exaptation, from outside the realm of biological evolution:

Plastic or paper? I first heard of the question after a couple of days of my arrival to the United States when I was out with my brother for Thanksgiving grocery shopping. I was confused and did not know what to say to the bagger. We did not have such luxurious option in Vietnam. We brought our own grocery bag to the market. And while I was thinking which one would do a better job, my brother yelled out from behind “plastic”. I turned to my brother with a weird puzzled look on my face and without even asking, my brother whispered making sure no one could hear him “they can be used as trash bags later”. After all it is not about which bag is a stronger bag but more about what else we can use them for after all that groceries are unloaded. …

In their argument for “Intelligent Design” [ID] IDoloters claim that some things (most notoriously, the bacterial flagellum) are so complex that they could only have occurred through conscious, purposeful design: They argue that there could be no adaptive advantage to evolutionary stages leading up to the complete mechanism, since it would not function until it’s all there in its complete form, so it must have been brought into existence, complete, in that final form.

This ignores the principle of exaptation, which recognizes that elements that later become parts of a complex feature or mechanism have adaptive advantage performing other, perhaps unrelated functions, in their earlier stages.

Ironically, this post itself is an example, insofar as the memes embedded in the post on grocery bags originally had no function in the discourse over evolutionary biology; but if people read this post, those memes will come to be disseminated performing functions unrelated to their earlier adoption in the post on grocery bags.

The intelligent blogger who wrote the grocery bags post did not have in mind the function of illustrating exaptation for the ID debate. The fact of that post being written by an intelligent blogger, and maybe this post too, is irrelevant to the basic principles of variation, distribution, adaptation, and exaptation that are seen to operate, as well, without conscious foreknowledge and purpose.


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