Evolution: convergence or parallelism (Introduction)

by David Turell @, Thursday, August 10, 2017, 18:34 (11 days ago) @ dhw

QUOTE: "The idea of contingency is perhaps best based on palaeontologist Dolf Seilacher's theory of constructional morphology. In this, features such as the elephant's trunk or the osprey's habit of catching fish with claws rather than beak result from three factors: adaptation (the selective component), evolutionary history (organisms must work with what they've inherited) and construction (how the material properties of living structures empower and constrain their form). From there, history takes over. Evolution is not a preordained, inevitable narrative. Neither is it a crapshoot, with random particulates disporting themselves until something works. Rather, it is like the game Monopoly. Where you go next is in part determined by where you are now; who you are is where you've been (your acquisitions); where you can go is determined by the throw of the dice, with limited possibilities and probabilities."

dhw: I would go along with the statement that evolution is not a preordained, inevitable narrative, since the vast higgledy-piggledy bush, with all its comings and goings, so clearly depends on what appear to be random changes in the environment. However, there is no mention here of the biggest problem of all, which is innovation. Every new organ that distinguishes humans from bacteria had to be invented. Ignoring the problem does not make it go away. But perhaps that is unfair and the author does tackle it – I can only comment on what is contained in the review.

DAVID’s comment: This is in direct contrast to Simon Conway Morris who firmly believes convergence is built into evolution. However this book (despite its atheist approach) fits my thought that there are built in patterns which would produce parallel developments.

dhw: It stands to reason that organisms faced with similar problems will find similar solutions. Maybe parallelism is a better term, but that’s a minor issue. “Built in patterns” are a crucial factor in the theory of common descent, since they provide the evidence of commonality. A theist might argue that his God provided all the patterns and preprogrammed or dabbled all the variations, or he might argue that his God provided organisms with the ability to invent and vary the patterns all by themselves. An atheist might argue that a limitless number of random combinations eventually resulted in one that led to life and the ability to invent and vary patterns. And an agnostic wrestles with the insoluble problem of origins, shakes his head, and admits to being clueless!

Comment: There are lots of clues; you just don't like them.


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