Front-loading and Preadaptation

Cooption, the process by which traits switch function, is something we predict to be important from the hypothesis of front-loading evolution. The Design Matrix lays out a step-by-step case for the logic of front-loading that leads to the realization that cooption is entailed by front-loading. Functional shifts are the very strategy that would work in an attempt to design the future through the present. This is a subtle, but important, point to grasp. Cooption is not some add-on to the front-loading perspective. Cooption is a prediction given that front-loading would not work without it.

Yet there is a simpler way to help people understand that cooption is, at the very least, a process that fits very comfortably within a teleological framework. It is the simple fact that cooption is tightly linked to preadaptation. Stephen Jay Gould sought to replace the word ‘preadaptation’ with the word ‘exaptation,’ where an exaptation is a character that retains its ancestral form while taking on a new function. And the process by which the trait switches function is called cooption.

The concept of preadaptation has been recognized by many to possess distinct teleological connotations, which is why non-teleologists have sought to replace it. This point is easily established:

Mechanism aside, there is a glaring problem with the word “preadaptation” itself. It is teleological; that is, it implies there is a direction or purpose to evolution (to make the trait adaptive), when in fact it is impossible to predict with any degree of accuracy the future of a biological character based on its current state. Evolution does not solve future problems. – McLennan, D. The Concept of Co-option: Why Evolution Often Looks Miraculous Evo Edu Outreach 1:247–258.

exaptation v. (formerly preadaptation) adoption of a character that had one use in an ancestral form into a new, different use in a descendant form.

Some biologists dislike the term ‘preadaptation’ as it could imply an intentional plan, which is contrary to the nature of evolution. Some alternative terms that have been suggested include “co-option” and exaptation.

pre-adaptation Adaptation evolved in one adaptive zone which, quite by chance, proves especially advantageous in an adjacent zone and so allows the organism to radiate into it. No selection for a future environment is implied. The concept is very similar to exaptation, but is often thought to have teleological implications.

preadaptation implies teleology

Gould and Vrba (1982) offered a terminological scheme through which they asserted that one can clarify differences between adaptations due to natural selection for their current role, and various aspects of such features that were not built by selection for their current role, but became useful for it after their inception. These authors argued that this was partly an effort to replace “preadaptation”, a concept they considered teleological.

So, as you can see, preadaptation is a concept with teleological implications. To see why it is that front-loading predicts cooption, simply consider front-loading as a state where the original cells were endowed with a set of preadaptations that would channel and guide subsequent evolution.

The hypothesis of front-loading evolution would thus predict that significant transitions in evolution would depend on preadaptation.

One response to “Front-loading and Preadaptation

  1. kornbelt888

    “The hypothesis of front-loading evolution would thus predict that significant transitions in evolution would depend on preadaptation.”

    Veering from nascent proto-science into genuine science here?

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