Natural Selection and what it didn\'t do for dogs... (Evolution)

by dhw, Monday, January 25, 2010, 12:04 (5415 days ago) @ xeno6696

MATT: What exactly do we mean by mutation? I ask this because the variations allowed by sexual reproduction itself is typically the cause of genetic changes. [...] 
Do I understand that both you and David would contend that the combination of sexual reproduction and natural selection are insufficient to describe life's diversity? If so, exhibit A: Dogs.-Life's "diversity" is too vague for me. My wife tells me there are 25,000 cultivars of daffodil alone! I don't suppose there are that many types of dog, but a daff is a daff, and a dog is a dog. If we're going to talk of variations, every individual specimen is different too, whether flower, animal or human. -The problem as I see it is twofold: 1) innovation, and 2) complexity. Your dogs may be different, but they still have all the organs and basic doggy characteristics of other dogs, and your new breeds are no more and no less complex than your old ones. There is nothing new here ... merely variation. But while you're thinking of dog to dog, I'm thinking of prokaryote to eukaryote to dog, duck, elephant, grasshopper, diplodocus, dormouse, eagle, crocodile...all the way up to Matt. And while you're thinking that it's all thanks to sexual reproduction, I'm thinking prokaryote to eukaryote to sexual reproduction, the senses, the circulatory system, the digestive system, the nervous system, the brain.... -Mutation as I understand it is the production of something new. My starting point is always the primitive forms of life, and then I try to figure out how they evolved to us, the most complex that we know of. The list of necessary innovations is colossal. If you bear in mind that these systems never existed, that the original mechanisms had to figure them out from scratch ... blindly unconscious though they were, and working solely through individual organisms going from one generation to another ... the inventiveness is too immense for us even to imagine, over no matter how many millions of years. And bear in mind that those individuals had already survived and reproduced, so they didn't actually NEED to come up with anything new. I have no idea how much of this innovation is due to random mutation and how much to the influence of the environment on the genetic makeup, or the response of the genetic makeup to the environment, but as I said before, the origin of adaptability in itself is an unexplained mystery. I don't know why you say that "the reason the forms of life we see are here, is because of a selection event. It explains adaptation." I would put it the other way round: adaptation explains why we see the forms of life we see. Natural selection gives precedence to the best adapted forms.-The argument relating to innovation is the same for complexity. Why should a light-sensitive nerve become an eye? If the nerve itself conveyed an advantage, that doesn't mean it needed to improve itself. Natural selection certainly couldn't improve it. All natural selection could do is ensure that the most sensitive nerves survived and were passed on, but what was passed on would still only have been a light-sensitive nerve. And we're not even considering the complexities of how a nerve comes to be a nerve and comes to be connected to the most complex of all the innovations, namely the brain. -This is the point at which one can only speculate. We know that all the organs did come into existence. We all agree that the simple did become more complex (although many simple forms of life have survived unchanged, so change is far from inevitable). But we don't know how, and mumbling the magic formula "evolution wooj wooj natural selection" explains nothing. How the mechanisms that drive evolution have been able to invent, refine their inventions, and add more innovations to their inventions, is still beyond our comprehension. One explanation (for those of us who believe in evolution) is that they were designed and programmed, with possible interventions made by the programmer. Another is that they all came about originally by chance, with a large number of interventions again made by chance. I think both versions accept that anything useful in a particular environment is likely to survive (= natural selection). David is convinced of the first theory, George of the second, and I'm left groping in the dark.