# Mechanism to allow for evolution. How did this mechanism come to be?

1. Aug 13, 2009

### vectorcube

Well, if we say that evolution is some gradual change of an organism from some form S to S* over a period of time. should there be some mechanism already in place to even allow evolution to occur?

To be even more clear.

For organism of form S, and successive generations S* , S**, S***....

S-> S*-> S**- >S***

such that each "->" means the gradual changes over a period of time. Should it not be the case that there exist a mechanism that "pre-exist" to allow the gradual change of organism from some form to another form over a certain period of time? If such mechanism exist, then how did this mechanism come to be what it is in the first place?

To be even more clear. Suppose you are given a series of printouts, and told that these printouts are all related in some way. Each printout is ordered( eg: printout 1, printout 2 ...) A guy by the name of DawinG comes along, and tell everyone that each handout is related to the previous handout by an computer algorithm. One can ask how did the printout come to be what it is by an appeal to the existence of a computer implementing an algorithm. I would say this computer+algorithm is the mechanism by which the evolution of printouts come to be what it is.

Last edited: Aug 13, 2009
2. Aug 13, 2009

### Staff: Mentor

Seems like mutation + natural selection is a valid mechanism, no? How do mutations come about naturally? That would seem to be straightforward given our EM environment, at least.

And another mechanism would be genetic variation, like hair color, or the color of moths. The moth coloration example is a pretty classic example of short-term evolution, correct?

Last edited: Aug 13, 2009
3. Aug 13, 2009

### Staff: Mentor

How did gravity come to be? These are philosophical questions, not scientific ones.

4. Aug 13, 2009

### vectorcube

5. Aug 13, 2009

### vectorcube

It is not. Asking for mutational mechanism that allow evolution to happen is a scientific question.

Last edited: Aug 13, 2009
6. Aug 13, 2009

### Monique

Staff Emeritus
I don't think that I understand your question. What don't you understand about mutation and selection?

7. Aug 13, 2009

### vectorcube

The hidden assumption in your last question is that i don  t know about evolution. This begs the question of what i don  t know about evolution?

Let me give you another try:

I am sure you agree that there is a genetic mechanism that allow natural selection to occur in terms of mutations in genes? Yes?

Well, i want to know how this mutational mechanism come about. How does it come to be what it is to allow evolution to happen?

8. Aug 13, 2009

### Monique

Staff Emeritus
Still I don't understand your point. You are talking about a mutational mechanism and natural selection interchangeably, while they are two very different things. DNA can mutate by a whole range of mechanisms. Some mutations are beneficial or detrimental for an organism, allowing for positive or negative selection in a population (think for instance about lactose tolerance). This mechanism is based on survival. There is also genetic drift (change in allele frequencie due to chance), if populations are isolated this genetic drift can cause them to become different from each other.

9. Aug 13, 2009

### Staff: Mentor

I would say both mechanisms involved are quite natural - ie they don't need to appear, they both are intrinsic to the world.

Changes in genome (mutations) are effect of the non ideality of the world - nothing is perfect, copying of information is not perfect either, so mutations are inevitable (this leads to a good question about whether the system implemented in our cells is not at some kind of optimum allowing species to ellastic enough to adapt to the environement, yet not allowing them to degenerate; but that's completely different thing).

Natural selection is a mechanism that doesn't require any special implementation. Whichever organism is better as something, will win over those inferior. That works even for non-organisms - when you have two competing chemical reactions, whichever is faster will consume more reagents and will have a better yield. That's the same.

10. Aug 13, 2009

### vectorcube

No, they are not the samething. By mutational mechanism, i mean the mechanism that allows mutations at the level of genes between successive generations.

Ex: Suppose someone ask why a rock cannot reproduce, and evolve into some other form of a rock. Well, rocks cant reproduce, because rocks don t have things like cells, DNA etc that allows it to pass to the *next generation* of rocks. I say the rock do not have the mechanism in place to allow it to pass on it s information to the next generation of rocks!

11. Aug 13, 2009

### vectorcube

Both of what?

what is "non ideality of the world" mean?

Do you think rocks can have natural selection? You don t think there is evolution at the level of genes? In the sense that there is a gradual change of a particular specie to another specie after some period of time. These two species would have different genetic information.

But this definition presuppose at least one organism to be in place for natural selection to occur. How then did this organism come to be what it is?

"That works even for non-organisms - when you have two competing chemical reactions, whichever is faster will consume more reagents and will have a better yield. That's the same."

But non-organism cannot have evolution. A rock cannot evolve into a different form of rock.

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12. Aug 13, 2009

### Staff: Mentor

There are two things involved - mutations and natural selection. Call it mechanism, process, whatever - both of them are needed.

That world is never ideal. For example there are no such things as ideal crystals - they always have some kinds of defects. There are no chemical reactions that can take only one path - there are always side ractions that lead to byproducts. And so on. It has nothing to do with life, it existed on the molecular lever since the first molcules appeared after BB.

No, although there are theories that point at some kind of rocks as an early matrix involved in the reproduction of genes. But rocks don't reproduce, so their evolution is out of the question.

Genes are involved in the evolution - but you are talking about evolution as it is occuring now. This is thing that evolved as well, starting from much simpler process, which get complicated with passing time. Principles are the same, biochemical details have changed.

You don't need organism to have a kind of evolution. Some kinds of RNA can replicate in vitro, AFAIR without a need of any other molecules but RNA itself and abundance of nucleotides. If you add heavy metal ions to such mixture, it will slow down the replication, nonethelss it will be still occuring. If you will separate reproduced RNA and repeat the procedure several times, each next generation replicates faster - RNA evolves and gets better at reproduction. Would you call it an organism?

13. Aug 13, 2009

### vectorcube

what is this "thing"? and what does this "thing" evolve from? Does this "thing" have genes?

I don t understand this.

But RNA would be some form of mechanism. How did this mechanism come about?

I generally consider RNA, DNA, cells etc to be necessary mechanism for evolutions to occur. If you could induce evolution of one RNA to another RNA. I suppose you can say RNA evolves.

I don  t understand your example, so i really do not know. Let me be more precise.

If X evolve, then X is an organism. I don` t really care for the converse.

14. Aug 13, 2009

### Monique

Staff Emeritus
Genetic information is key, if you have a strand of RNA it can mutate and its information content can change. This is where it starts. Did you read my signature?

15. Aug 13, 2009

### vectorcube

I understand what you are saying, but it seems to not be case the other way around.

Let me put it this way. If we say RNA is the key that allow organism to change. My question would be where did this RNA come from? Same with any mechanism you can name.

16. Aug 13, 2009

### sganesh88

Vector cube, see if i've understood your question right.
For eg., consider the situation at which some organism first evolved eyes. You say there should have been some mechanism that resulted in or triggered the mutation of an existent gene or development of a new gene that then carried the code for the construction and fuction of the eyes. Am i right in understanding what you say?

17. Aug 13, 2009

### vectorcube

I would not think of such mechanism as causing, or triggering something to happen. I would think of the mechanism as a pre-condition that allows mutation to occur. Similarly, I would say the computer hardcare is the precondition that allows the computer to output anything.

18. Aug 13, 2009

### sganesh88

"allowing" doesn't make sense. As if the print out wants to come out and the computer is kind enough to "allow" it. The computer through its program lines and memory; and the printer through its hardware work jointly causing the paper to filled with some words.

19. Aug 13, 2009

### Monique

Staff Emeritus
So your question is how the first strand of replicating information came to be? With "mechanism" you mean genetic information?

20. Aug 13, 2009

### vectorcube

Maybe "allowing" is the wrong word. A better word might be "necessary condition". A computer is a necessary condition to have computer printouts.

Last edited: Aug 13, 2009