questions for evolutionists

[SWScorch]

I hope this desn't turn into a flamewar as I am not provoking anyone, especially since I am asking this of people who hold the same beliefs as I do. However, I realize that I am ignorant in several areas, and would like to have some things explained.

Basically, I'm wondering how certain traits were developed in the first place. For instance, hippos secrete a natural sunscreen that protects their skin from the sun. This seems like a perfect adaptation to their environment, but how does something like that occur in the first place? If you follow the common acenstry viewpoint, then at one time there were creatures which did not secrete sunscreen, and then somehow the ability was developed. Is it formed from a freak genetic occurance? Even as a follower, I find it difficult to believe that a chance genetic mutation could cause an animal to secrete an oil which which just so happens to limit the harmful effects of its environment.

I was under the impression that the theory of creatures developing characteristics in response to their environment was largely discredited, or does that still hold water? If that is still viewed as holding true, then things make a lot more sense.

 

[Trevelyan]

mutation is the ultimate source for genetic variation

 

[ElFenix]

you secrete all sorts of oils. the fact that out of all critters, most of which live in the sun for a good part of their lives, only one developed natural sunscreen, should tell you that yes, it probably is a freak occurence.

 

[Trevelyan]

Random mutations are key to natural selection and therefore evolution:

1) "Heritable variation is at the heart of Darwin's theory of evolution, for variation provides the raw material on which natural selection works."
2) "Two random processes, mutation and sexual recombination, create variation in the gene pool of a population."
3) "New alleles originate only by mutation... Most mutations are lost when the individual dies."
4) "A mutation is like a shot in the dark: Chance determines how it will strike and how it will alter a gene."

And remember, "Mutation is, in itself, very important to evolution because it is the original source of the genetic variation that serves as raw material for natural selection."

EDIT:

Basically what that means is all new traits are a result of random chance mutations. Natural selection only works with the genes that are available, it cannot create, only recombine, which means there is a definte limit as to the extent that natural selection can bring about CHANGE over any amount of time. That is why mutation is key. Without mutation, natural selection cannot be the mechanism for macroevolution.

 

[Gibsons]

Originally posted by: SWScorch
I hope this desn't turn into a flamewar as I am not provoking anyone, especially since I am asking this of people who hold the same beliefs as I do. However, I realize that I am ignorant in several areas, and would like to have some things explained.

Basically, I'm wondering how certain traits were developed in the first place. For instance, hippos secrete a natural sunscreen that protects their skin from the sun. This seems like a perfect adaptation to their environment, but how does something like that occur in the first place? If you follow the common acenstry viewpoint, then at one time there were creatures which did not secrete sunscreen, and then somehow the ability was developed. Is it formed from a freak genetic occurance? Even as a follower, I find it difficult to believe that a chance genetic mutation could cause an animal to secrete an oil which which just so happens to limit the harmful effects of its environment.

I was under the impression that the theory of creatures developing characteristics in response to their environment was largely discredited, or does that still hold water? If that is still viewed as holding true, then things make a lot more sense.

Don't get confused by thinking of individuals evolving, you have to think of whole populations.

More directly to your question, shining bright sunlight on cells won't cause them to make some UV-protective substance. However, put a large population in an environment with a large amount of sunshine and, given a lot of time, you might well see evolution in response to the environment.

As for hippos specifically, I'm not familiar at all with the chemistry and biology behind that story, but here's a guess - there are lots of chromophores and such made by mammals; cytochrome p450s for breaking down stuff in the liver, pigments in hairs, melanin, etc.

The hippos likely had something like that, some individual(s) had alleles which favored getting these pigment(s) to the skin. These were selected, and there ya go... It's unlikely there would have been one freak occurance where this pigment suddenly came about.

 

[SWScorch]

So, basically, it was just a freak genetic mutation that caused hippos or their ancestors to start secreting a sun blocking ointment, and then that mutation got passed through the generations until it defined the species?

 

[Gibsons]

Originally posted by: SWScorch
So, basically, it was just a freak genetic mutation that caused hippos or their ancestors to start secreting a sun blocking ointment, and then that mutation got passed through the generations until it defined the species?

no.

edit

in any population you will have variation. Think of anything you can measure about a human being, you'll find more than a 10% variation in that property in the population. The hippos had some sort of chromophore (or whatever it was) that worked, kinda sorta, maybe in a crude way. Among the population, some were just better than others at getting/making/using this system. They didn't go from being zero percent efficient to one hundred percent. They started at say, one percent to two percent. The two percenters survived and reproduced a little better.

 

[cmp1223]

I guess you could say that a population muated to secrete some type of fluid, then mutated to secrete different types of fluid. Those whose fluid protected them from the sun survived.

 

[Trevelyan]

For the hippos specifically, several conditions would have to be met:

1) At least one hippo must possess a gene that expresses itself by secreting UV-blocking oil. (Mutation is the source for this new gene.)
2) The gene must also be in his gametes, so he can pass it on to his offspring.
3) The environment must change so to allow natural selection to favor the hippo with UV-blocking oil.
4) ALSO, the hippo must be given a benefit that allows him to survive better and reproduce.
5) The gene will then be passed on and if it becomes neccessary to have UV-blocking oil secreted all the hippos will have it eventually.

 

[LtPage1]

"evolutionist" isnt a word. by using it, youre just making "Creation Science" more credible.

 

[SWScorch]

Originally posted by: LtPage1
"evolutionist" isnt a word. by using it, youre just making "Creation Science" more credible.

it is now! mwahahahaha!

 

[lokiju]

Interesting question, I've wondered about the fish that develop these unique traits for their deep ocean environments or lightless environments myself.