Science vs. Religion: (Chapter 4) (Humans)

by xeno6696 , Sonoran Desert, Wednesday, July 27, 2011, 20:42 (4867 days ago) @ dhw

dhw--Tony & David too for that matter,
> MATT: I've mentioned the Beta-Lactamase experiment in which Barry Hall knocked out the gene that allowed a bacteria to digest lactose. A small population (that no longer had any recollection of lactose because of the knockout) modified a protein that allowed them to consume lactose again. This is an example of creation of a new function by random mutation and natural selection only.
> 
> I have a different interpretation of this experiment, so do by all means correct me. Firstly,according to your account it wasn't a "novel protein", but a modification of a protein to replace a missing gene. As I see it, this shows that a particular bacterium found a way to revert to type in order to aid its chances of survival. It is an example of adaptation, not innovation, and did not lead to a new species of bacterium. The mutation can hardly be called "random", since it involved a very specific adaptation to restore an ability that was clearly integral to its nature. How this shows the creativity of NS is beyond me. Does the experiment prove that NS can create new organs and new species? Of course not. If the pressure to survive actually created means of survival, no creature would ever die! The great question is how the bacterium managed to modify the protein, and that is the core of our disagreement. You "see no reason at all to assert that Natural Selection isn't enough", and yet even your own analysis of the case shows the vital role played by mutation. Without mutations (or changes of some kind) everything would remain exactly as it was, and there would be nothing for Nature to select from! 
> -The beta-lactamase function was NOT integral to the species. Several generations continued with the bacteria moving along just fine--only more slowly as its only means of getting energy was pyrolysis. Pyrolysis (if memory serves) delivers 2 ATP molecules for every 1 ATP expended, but the Beta-Lactamase allows for a much greater payout. (Not sure if it allows for Krebs or not, but I don't think so.) -At any rate, you seem to be arguing that the Bacteria could somehow remember what was removed from its genome, and that some other mechanism other than random mutations caused the new protein to be created. The protein created WAS new. It was not the same Beta-Lactamase that the organism began with, and was not found in wild-types. Hall collected sequence information from each generation of bacteria over time, and the gene sequence changed in a manner consistent with random mutations, ie frame-shifts and recombination mistakes that ultimately ended up in a creation of the new protein. On this particular experiment, I think it clearly demonstrates that some beneficial changes CAN come by chance. (Not ALL. But at least ONE.) -Your next charge is that this isn't a case of evolution, but I think your thrust is misguided; you should be attacking the fact that it is an example of "microevolution" and not an example of "macroevolution." Of this charge, you are absolutely correct. However, biologists, if they had found two strains of E. coli in the wild that had two different types of beta-lactamase they WOULD be considered different species. As I said before, evolution as viewed by working scientists is this statement: "A change in the frequency of Alleles from generation to generation." -David, if you claim epigenetic mechanisms were at work here, the door is open for you! This is exactly one aspect you can argue: the changes look random, but there is epigenetic machinery at work that was slowly working to restore a lost function. It's a testable hypothesis, but until that work has been done, Natural Selection stands. Again, I accept Natural Selection here because a better (testable) explanation doesn't exist. I won't accept another explanation until the work has been done--I agree that epigenetic mechanisms will be an important creative force for evolution, but I won't support it until it's been explored. -> In your post to Tony, you quite rightly emphasize that "Evolution is clearly more complex than pure random mutations." Yes indeed. And it is clearly more complex than Natural Selection, which does not CREATE anything.-And I challenge that, still by what I said above. If an organism is under stress and its body's response is to alter its chemistry, and that chemistry is passed on to its offspring, then we just had an event of "evolution by natural selection."

--
\"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.\"