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A little help

Discussion of everything related to the Theory of Evolution.

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A little help

Postby Grisner » Tue Jun 25, 2013 5:17 pm

I am just trying to get a few things clear

1) All life came from a single specimen?

2) All evolution stems from random mutations? (random being the key question here)

3)Related to question 2, but environment does not play a role in mutations other than natural selection?

4) Vestigial structures can have important functions? or not?

5) Any and all vestigial structures must come from ancestors that utilized that structure as a population, not just sparse individuals?

I think I have a few more but can't seem to think of them at the moment. Any assistance appreciated.
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Postby JackBean » Wed Jun 26, 2013 2:39 pm

1) all life present nowadays on Earth, yes

2) yes

3) depends what you imagine under playing a role. It can provide mutagens (e.g. light, all kinds of stress, chemicals), but these still provide random mutations, so it's not like something specific.

4) what exactly you mean by vestigial structures?
http://www.biolib.cz/en/main/

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Re: A little help

Postby Grisner » Wed Jun 26, 2013 3:57 pm

In regards to vestigial structures I am referring to organs such as the appendix or bones and limbs similar to what is occasionally found in whales. Essentially organs, limbs etc that are believed to once have been more developed in ancestral species that have lost their primary functions but still remain in the animal on a permanent basis such as the appendix or only occasionally found such the human's sixth digit.
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Postby JackBean » Thu Jun 27, 2013 9:33 am

in that case:

4) probably not, otherwise it would not be vestigial. Something may get smaller or something if that's sufficient, but used. However, it can get vestigial only if it's not used. IMHO

5) is there any organ in general, that is used only by individuals?

six digits in humans (or mammals in general) are disease, not vestigial organ
http://www.biolib.cz/en/main/

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Re: A little help

Postby Grisner » Thu Jun 27, 2013 5:23 pm

I tend to agree with you that vestigial structures should not have needed functions. However, I have read some material that states that they can have lesser functions as their primary functions become obsolete. It seems to be somewhat confusing depending on where you read.

As far as organs used by individuals? Not really, in regards to this area I was really talking about fingers, limbs etc. It is an interesting note that i have read that there is an organ in the male nose used to detect the estrus of females that is absent in most human males, although I didn't put much research into that area.

I was unaware that the sixth digit that appears sparsely in the human population had been classified a disease. I am aware of the multi-legged frogs that gave everyone a scare a few years back that was caused by spirochetes. I will have to look further into this "sixth digit" disease.
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Re: A little help

Postby thoffnagle » Thu Jun 27, 2013 6:36 pm

Grisner wrote:1) All life came from a single specimen?


Probably.

Grisner wrote:2) All evolution stems from random mutations? (random being the key question here)


Yes. Those random mutations are then selected for or against. They may also be neutral but subject to future selection.

Grisner wrote:3)Related to question 2, but environment does not play a role in mutations other than natural selection?


Environment may cause mutations - e.g., UV light, radiation, etc. cause DNA to break.

Grisner wrote:4) Vestigial structures can have important functions? or not?


Vestigial structures, by definition, do not have function (if a function is discovered, then it is no longer considered to be vestigial). However, that does not mean that they didn't have a function in the organism's ancestors - if not, they would not have developed. And the function of a structure decreases as it is no longer needed. E.g., legs in whale ancestors were originally used for swimming, but gradually lost that function.

Grisner wrote:5) Any and all vestigial structures must come from ancestors that utilized that structure as a population, not just sparse individuals?


Yes. It would be extremely unlikely that a structure would develop in a single individual, then a huge mutation would occur to make that structure unnecessary in all of its descendants. I don't know about multiple digits in humans, but additional legs in frogs is a developmental glitch.
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