Inference and its role in NS (General)

by xeno6696 , Sonoran Desert, Monday, January 24, 2011, 04:05 (5054 days ago) @ dhw

dhw, I really wish I could add diagrams to my posts here...
> MATT: It's in the language of biologists; an event that begins the process is called "selective pressure." While the organism is under pressure, it must find a way to adapt, behaviourally or molecularly. 
> 
> If an organism is already perfectly adapted, it doesn't need to change. What you call "adapt molecularly" is the point at issue, because without that mechanism (plus the mechanism that produces innovations such as sex), there can be no evolution. What you have is therefore three stages, two of which speak for themselves: 1) if organisms don't adapt to the conditions they will die (selective pressure); 2) some organisms adapt/change/innovate; 3) those that have changed appropriately survive (natural selection). Phase 2 is the one that causes us all the problems.
> -At core, is selective pressure. I understand evolution to be destructive as well as constructive; selective pressure is the cause that moves an organism to continue to survive or become extinct.-We need to consider what Dawkins is saying here. For natural selection to explain the "whole of life," we need to define what it is that it is selecting for. Ultimately we know that it is genes that are being selected for. I will have to dig up the name of the experiment done in the 1980's, but the experimenters deliberately knocked out a bacteria's natural ability to digest lactose. They then cultured these bacteria and reintroduced them into a lactose-rich media. What ended up happening was that the bacteria appropriated machinery that performed some other function, and used that (inefficiently) to again be able to ingest lactose. In this case the selective pressure was lactose, and the selection was for the new gene. -As far as natural selection is concerned, it does not matter whether or not we know exactly how the bacteria did what it did. We know its beginning state, its end state, and that the mechanism of change was in co-opting a different gene. -Modifying "what are we selecting for" the answer becomes clear: Selective pressure operates against only the genetic material that came before that date. The mechanism for change relies solely upon the collective history of the organism. Natural Selection explains both why organisms live and die out, and why we have the diversity we have today. Natural Selection works against existing genes to accomplish all of this. I think this is complete as I can be in regards to the Dawkins/Pigliucci formulation, without stepping into their heads. -So I think your #2 above is answered as it can be. In the Dawkins view, your question gets pushed all the way back to abiogenesis, because life is defined as a recursive function that consistently relies upon its prior states. Explanations such as the exact mechanisms that created eyes or sex are seen as only filling in the details of what is explained by what I discussed above. -I agree that it's the corner-cases that raise red flags. I unfortunately will have to wait for biologists to answer these questions more completely.

--
\"Why is it, Master, that ascetics fight with ascetics?\"

\"It is, brahmin, because of attachment to views, adherence to views, fixation on views, addiction to views, obsession with views, holding firmly to views that ascetics fight with ascetics.\"