assumptions of evolution

[gamespotter10]

Now, I am fully aware of the evidence for common ancestry between humans and apes.

However, I think there may be some assumptions about evolution

the first one is that abiogenesis happened only once

the second one is that all life on earth shares a common ancestor.

what evidence for UNIVERSAL common descent do we have?

 

[shevar]

Now, I am fully aware of the evidence for common ancestry between humans and apes.

However, I think there may be some assumptions about evolution

the first one is that abiogenesis happened only once

the second one is that all life on earth shares a common ancestor.

what evidence for UNIVERSAL common descent do we have?

Evolution doesn't rule out that abiogenesis happened only once. Evolution only states that living creatures over thousands of generations will change and adapt to it's surroundings in some way or another.

The origin of life is a different subject all together to be honest, and even the most logical non-theist theories don't rule out that there could have been several different early lifeforms. It's just not something that can currently be proven or disproved.

 

[gamespotter10]

Evolution doesn't rule out that abiogenesis happened only once. Evolution only states that living creatures over thousands of generations will change and adapt to it's surroundings in some way or another.

The origin of life is a different subject all together to be honest, and even the most logical non-theist theories don't rule out that there could have been several different early lifeforms. It's just not something that can currently be proven or disproved.

okay then.

but what evidence do we have that all life on earth shares a common ancestor?

 

[Split Rock]

Now, I am fully aware of the evidence for common ancestry between humans and apes.

However, I think there may be some assumptions about evolution

the first one is that abiogenesis happened only once

This has nothing to due with evolution and is not assumed at all.

the second one is that all life on earth shares a common ancestor.

This is inferred from the evidence, not assumed.

what evidence for UNIVERSAL common descent do we have?

The twin-nested hierarchy of life, for one.

 

[gamespotter10]

This has nothing to due with evolution and is not assumed at all.


This is inferred from the evidence, not assumed.


The twin-nested hierarchy of life, for one.

could you explain how a nested hierarchy is evidence for universal common descent?

 

[Bobfr]

okay then.

but what evidence do we have that all life on earth shares a common ancestor?

Cause every living organism on this planet have common characterics such as :
- DNA based genetic code
- similar process of replicating this DNA
- DNA transcoded into proteins, all composed of amina acids
And a lot of other stuffs. See info on Last Universal Common Ancestor here : http://en.wikipedia.org/wiki/Last_universal_ancestor As usual this is a theory And that do not mean that L.U.C.A. was the first living organism.

 

[shevar]

okay then.

but what evidence do we have that all life on earth shares a common ancestor?

I personally don't "care" about the exact origin of life, it is a question shrouded in an pretty much unimaginable long timespan.

The problem lies in the fact that;

A: We can only find very few of the actually fossilized creatures with our current technology (we can't dig deep enough, we can't detect fossils from range through rocks, we can't find fossils which are under the oceans etc.).

B: Fossilization is a rather rare occurrence.

C: Fossils surviving hundreds of millions to billions of years are even more rare.

In my opinion for science to have a definite awnser (which might or might not be there) to the question where did the first lifeforms came from we would probable either need to figure out how to travel in time or find another planet which has a similar setting as earth was 3 billion years ago.

The proof that is there is that a lot of current groups of species had common ancestors, yes it has gaps but evolution is a far better and more accurate theory then what the bible proposes (or any other religion that I've read a bout for that matter).

 

[Loudmouth]

could you explain how a nested hierarchy is evidence for universal common descent?

If all life did not share a common ancestor (or more accurately, a common ancestral gene pool) then we would expect a non-nested hierarchy. For example, there is no reason that all life should share the same codon usage. There is no reason that ATG should code for methionine in all organisms if they do not share commmon ancestry.

 

[gamespotter10]

If all life did not share a common ancestor (or more accurately, a common ancestral gene pool) then we would expect a non-nested hierarchy. For example, there is no reason that all life should share the same codon usage. There is no reason that ATG should code for methionine in all organisms if they do not share commmon ancestry.

is it at all possible that something other than ATG (whatever that stands for) could code for methionine?

 

[Vene]

If we had uncommon ancestry the DNA of all organisms would not be composed of adenine, guanine, cytosine, and thymine. Instead it could easily have uracil like what RNA does or not have four nucleotides. Or it could have one of the various other nucleotides. (there are some structures of them over here.)

 

[Oncedeceived]

IF all living forms are from a common Creator the same would apply...no?

 

[Vene]

IF all living forms are from a common Creator the same would apply...no?

It's possible, but that only adds another unexplained (and unsupported) element. And it does not explain the nested heirarchy. It also brings up the question of how did the creator come into being.

(And I don't put any stock into ID groups as it's thinly veiled creationism. We even have a transitional species cdesign proponentsists)

 

[Loudmouth]

is it at all possible that something other than ATG (whatever that stands for) could code for methionine?

Absolutely. It's very possible. In fact, some scientists are looking for life that does not follow the universal codon usage. It is possible that there is a species of life that does not use ATG (or a third base variation) to code for methionine. There is no physical law that states "ATG must code for methionine".

 

[shevar]

It's possible, but that only adds another unexplained (and unsupported) element. And it does not explain the nested heirarchy. It also brings up the question of how did the creator come into being.

(And I don't put any stock into ID groups as it's thinly veiled creationism. We even have a transitional species cdesign proponentsists)

ID is a slipperly slope, if tomorrow are new scientific theories are introduced that can stand up to peer reviewing and such then the premise of ID has to be changed again.

The main problem with that theory is that the the I in ID is not based on any evidence but currently is only founded on discrediting evolutionism. Not to mention it is rather hard to argue which god exactly would have been responsible for creating the world (was it the Christian god or was it Odin or whatever).

 

[Loudmouth]

IF all living forms are from a common Creator the same would apply...no?

If all species used different codons would that be evidence against there being a creator?

The reason that we humans reuse designs and code is that we like to save time. This wouldn't be the case for an all powerful creator who lived outside of space and time. It would be just as easy to design every species with dissimilar codon usage.

Yet another example of why creationism is incapable of producing predictions.

 

[Oncedeceived]

It's possible, but that only adds another unexplained (and unsupported) element. And it does not explain the nested heirarchy. It also brings up the question of how did the creator come into being.

True. All I want injected is that nested hierarchy does not eliminate or deny that God was not involved for those who would claim that.

(And I don't put any stock into ID groups as it's thinly veiled creationism. We even have a transitional species cdesign proponentsists)

Transitional species again does not say that a Creator creating with the same elements/chemicals/ and so forth would not look the same way.

 

[Oncedeceived]

If all species used different codons would that be evidence against there being a creator?

The reason that we humans reuse designs and code is that we like to save time. This wouldn't be the case for an all powerful creator who lived outside of space and time. It would be just as easy to design every species with dissimilar codon usage.

Of course that is impossible to assume.

Yet another example of why creationism is incapable of producing predictions.

Oh it makes predictions, if it didn't evolutionists could not say that it has been falsified.

 

[Vene]

True. All I want injected is that nested hierarchy does not eliminate or deny that God was not involved for those who would claim that.

That is logically unsound. You are adding an extra entity that has no support from the data. Or do you also say that God does things such as holds atoms together using the strong nuclear force? There is the same amount of evidence for both.

Transitional species again does not say that a Creator creating with the same elements/chemicals/ and so forth would not look the same way.

Reread what I wrote, I said that creationism and ID are the same and stated a very poor example of revising a creationist textbook into an ID textbook. Basically, you take "creationist", highlight "reastion"and replace it with "design proponents" yielding cdesign proponentsists, as such it's a great example of point mutation. (actually, several point mutations and a few additions)

 

[Loudmouth]

Of course that is impossible to assume.

That's kind of my point. You assume that a creator would use the same codon usage for all life. Is that an impossible assumption to make?

Oh it makes predictions, if it didn't evolutionists could not say that it has been falsified.

Creationism is unfalsifiable because it is made thus by it's proponents. Radioactive decay disproved a young earth, but creationists then argue, ad hoc, that decay rates were not constant throughout history. Or, even worse, they propose Omphalos like ideas, such as star light being made in transit.

 

[Naraoia]

is it at all possible that something other than ATG (whatever that stands for) could code for methionine?

ATG is adenine-thymine-guanine

Yes, it is perfectly possible. (Chemistry people, correct me if I'm talking rubbish ). Codons don't determine amino acids directly; codons in mRNA bind to a complementary anticodon on a tRNA molecule, which has an amino acid stuck to its other end. As far as I know which tRNA binds which AA is pretty arbitrary; the correspondence is determined by the enzymes (aminoacyl tRNA synthetases) that sew tRNA and AA together. These have separate recognition sites for the anticodon and the amino acid.

The "universal" genetic code is actually not universal, although most of the codons mean the same AA or punctuation between any two organisms; here is a summary of the different variants.