Evolution: a different view (Introduction)

by David Turell , Saturday, May 02, 2015, 21:50 (3492 days ago) @ David Turell

dhw: ...exaptations would also be inventive adjustments to existing organs.
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> > 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. 
> > And: You totally miss the point about exaptation's. They appear well before any use of them is found and they are not necessary at the time of appearance. That is the definition of them.
> > 
> > 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. 
 
 This point (1) fits my definition of appearing ahead of time for no good reason and not used at all. Please re-read in my book (S vs R) pages 130-131 for further discussion. The larynx and other changes are right on point.
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> > dhw: 3. a morphological or physiological feature that predisposes an organism to adapt to a different environment or lifestyle. 
> > 4. predisposition toward adaptation.
 
 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.
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> > dhw: None of these definitions suggest features that have hung around for thousands of years doing nothing. If anything, they seem to suggest innovative use of existing features.- Wrong interpretation of the first type of definition:
 
 "While an exaptation is co-opted from another or no apparent use, an adaptation is constructed by natural selection for its current use, Gould and Vrba wrote." Note the bold. It has both meanings, and there are many examples of both.
 
 "Others, however, have found the concept of exaptation difficult to separate from adaptation. The philosopher Daniel Dennett writes in his book, "Darwin's Dangerous Idea" (Simon & Schuster, 1995): “If you go back far enough, you will find that every adaptation has developed from predecessor structures each of which had some other use or no use at all.'” (my bold)
 
 "A recent study, published in Nature, used a computational method to examine the potential for exaptation within metabolisms. The researchers concluded that every adaptation, in this case the ability to live off glucose, was accompanied by multiple, potential exaptations, or the latent ability to use other fuels. This result implies that if an organism is put into an environment offering only a food it had never before encountered, that organism may be able to eat the foreign food just fine and so survive. This result indicates that many beneficial traits may have gotten started as exaptations, the researchers write." 
 
 {In other words, existing, but not used at all until a need arose.} ( my comment) 
 
http://www.livescience.com/39688-exaptation.html -"Thirty-one years ago, Gould and Vrba suggested that repetitive DNA sequences known as transposons, which originated from viruses, might serve no direct function at first, but may be used to great advantage later on. Since then, research has shown that transposons played an important role in the evolution of pregnancy. “They come from viruses, but they can be utilized for something they are not built for,” said Günter Wagner, an evolutionary biologist at Yale University and Andreas Wagner's former doctoral adviser. The two are not related." (my bold)-https://www.quantamagazine.org/20130904-evolution-as-opportunist/
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> > dhw: How do you imagine these early hominids communicated? Do you not think they made sounds? And do you not think their lowered larynx would have helped them to make different sounds using their own particular “language”? Or do you mean Lucy had no idea she could one day learn to speak English?
 
 She had no idea. Look at my book or read " The Ape That Spoke", by John McCrone, 1991. I have it well annotated. DHW, I feel you are in a funny mode, trying to teach me what I already know. Is this the way to defend agnosticism? 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.