Are mutations truly random or are they guided?

Most mutations are deleterious, so your conclusion that the cell guides processes that usually hurt or kill it makes no sense.The true driving force behind evolution is natural selection, the originator of adaptation. Random mutation is merely one source of variation that natural selection draws upon as it molds populations of organisms toward better adaptation to their environment through successive generations.--Percy

Hi Bolder-dash,Given that we don't know everything and never will, there will always be questions for which we have few or no answers. Concerning examples of positive mutations in mammals, I'd be surprised if we know of very many. Mammals have very long generation times and very complex morphologies and functions, and mapping genes to morphology and function is a lengthy process. Random mutations are far more likely to be deleterious than advantageous. Their deleterious nature can be very extreme, even fatal, while their advantageous nature can be only subtlety incremental, and this is because large changes are bound to be bad.But as Dr Adequate alluded earlier, population genetics tells us that mutation rates are consistent with evolutionary processes. This was all worked out in the 1920's, and it resulted in what is referred to as the Modern Synthesis, or the synthetic theory of evolution, which is the merging of genetics with the theory of evolution. Prior to the work of the population geneticists it was considered possible that genetics would not prove consistent with evolution, thereby bringing Darwinian evolution into question, but the research revealed that they reinforced each other. Your concerns that mutation rates are not consistent with evolution was addressed nearly a century ago.Advantageous mutations are easier to identify in organisms that have a very short generation time. Some bacteria reproduce as often as every 20 minutes, but identifying advantageous mutations is still very difficult, because the advantage is usually very subtle. Identifying bacteria that look identical to all the other billions of bacteria but that reproduce 1% or 2% more successfully or that survive 1% or 2% more successfully is very difficult. That's why experiments often involve drastic environmental changes, because positive mutations can be identified simply by looking at bacteria that didn't die.--PercyPS - Problems with moderation should be taken to the Report discussion problems here: No.2 thread.

It does seem strange that the creationists in this thread seem to be arguing against the possibility of advantageous mutations when the thread's premise is that positive mutations happen and that they are "directed by the cell and by cellular processes." (see Message 1)--Percy

And assuming that neutral mutations can happen to unexpressed regions of DNA, that would be like changing "# This is a comment" into "# This is still a comment".A bash analogy? Are you sure you're a biologist? --Percy

I read forward and found you're yet unconvinced, so let me add my voice to the others: a neutral mutation in one environment is definitely not neutral in all other environments.The reason a mutation is neutral is important. If neutral because it is completely unexpressed, for example a point mutation that doesn't affect the gene at all and the gene continues to produce the same protein as before, then that kind of mutation should be neutral in all environments.But if neutral because the change it produces has no effect on reproductive success, then the neutrality is definitely specific to that environment. In other environments the change may not be neutral. For example, say a mutation changes a beetle's carapace color from brown to musky red, and in the current environment that turns out to be neutral. Then one day the local ecology is invaded by a beetle predator that can see musky red better than it can see brown. Guess what, the mutation isn't neutral any more.--Percy

Hi Bolderdash,My reply in Message 28 wasn't intended as a defense of the existence of positive mutations. The very premise of this thread assumes the existence of positive mutations and asks whether they're random or guided. I at first thought you were claiming that evolutionary processes were insufficient to explain the history and diversity of life, and that's the position I was addressing.But if you don't even accept the possibility of positive mutations, which is what I now understand your position to be, then you're in the wrong thread.--Percy

Why do you think that a change in color must provide a "noticeable advantage?" Why must it be an advantage? Couldn't be a "noticeable disadvantage?"And why must it be "noticeable?" Are you saying you can imagine no environment in which a change in color would be neutral? Perhaps an environment where the beetle's only predators operate by smell? And then a new predator enters the environment that operates by sight?If you still don't like the "beetle color change" example then just invent one of your own where a mutation causes a detectable change that is neutral regarding reproductive success. Or are you operating under the misimpression that expressed mutations can never be neutral?--Percy

Hi Herebedragons,My comment was directed at those who rejected the thread's premise as stated in your Message 1. I assume you don't reject your own premise, so I don't understand why you think the comment may also have been directed at you. Didn't I describe the premise of the thread correctly?--Percy