Evolution: a different view (Introduction)

by dhw, Monday, May 04, 2015, 18:40 (3490 days ago) @ David Turell

dhw: ...exaptations would also be inventive adjustments to existing organs.
DAVID: Exaptation's appear thousands to hundred of thousand years before any use is found for them. That is a key issue in the idea of pre-planning. 
dhw: I can't find any definition that supports this view. On one website I found the following definitions:
1. a process in which a feature acquires a function that was not acquired through natural selection. 
2. a feature having a function for which it was not originally adapted or selected. -DAVID: This point (1) fits my definition of appearing ahead of time for no good reason and not used at all. -Where do you see (hundreds of) thousands of years before the feature had any use? The existing feature acquires a new function, that's all.
 
dhw: 3. a morphological or physiological feature that predisposes an organism to adapt to a different environment or lifestyle. 
4. predisposition toward adaptation.-DAVID: These points are also part of a differing definition which has to do with adaptation of an existing part to new function, like the panda thumb.-The first two definitions entail innovation, whereby existing features acquire new functions (no mention of the feature being useless for thousands of years), the last two definitions entail the ability to adapt as opposed to innovating.
You go on to quote various examples of writers referring to alternatives (features which “had some other use or no use at all”) - which I'll come back to - and an experiment proving that organisms might be able to eat foods never before encountered - an ability which you say is “existing, but not used at all until a need arose”. In this case, the organism's existing digestive mechanism could clearly adapt, so are you saying it never used its digestive system before?-I have a problem with your concept of uselessness. Even now there is a huge kerfuffle over “junk” DNA, which suddenly scientists are finding serves a useful purpose. How does anyone know that the features which changed their function were useless before? The examples mentioned - feathers, fins and limbs, the lowered uvula, digestion - do not relate to anything originally useless.
 
However, I am not trying to teach you something you already know. When you confront me with your “proofs”, I try to test them. You wrote: “There are two definitions and some confusion between adaptation and the two types of exaptation. I use the one you don't like because it implies pre-planning as you have noted.” It seems to me that there is enormous confusion, your two types involve innovation and adaptation, and both fit in just as well with an autonomous inventive mechanism as they do with pre-planning. Perhaps if you can explain to me how you know Lucy did not use her lowered uvula to make sounds intelligible to her peers, and how you know that whatever examples you can think of were useless (hundreds of) thousands of years before they became useful, it would help.-xxxxxxx-I'll have to deal with the Tattersall quote (also used in your first book) and the Gould quote another time.