Madagascar and Australia, a question for creationists.

[Speedwell]

so what? they are still very similar.

But they are not morphologically and genetically identical, which is what it would take to disprove evolution. All that the similarity shows is convergent evolution.

 

[xianghua]

But they are not morphologically and genetically identical, which is what it would take to disprove evolution. All that the similarity shows is convergent evolution.

even if we are talking about one gene?

 

[Speedwell]

even if we are talking about one gene?

I think you are being deliberately obtuse.

 

[Speedwell]

did you forgot natural selection? if one sequence can evolve once it can evolve twice.

But the odds are much against it. In the case of the wing, the pterosaur wing evolves from a limb which is morphologically and genetically different than the limb of the bat's precursor mammal. Aerodynamic considerations involved in selection might be expected to result in a wing which is to the untrained observer superficially similar to the bat's wing (although in this instance the differences are sufficient even for an amateur to notice) but the underlying genetics will betray the similarity. The starting points of the limb-wing transition are too different genetically.

You aren't, by any chance, a Platonist?

 

[xianghua]

But the odds are much against it. In the case of the wing, the pterosaur wing evolves from a limb which is morphologically and genetically different than the limb of the bat's precursor mammal.

first; how do you know? do you have any sequence of a pterosaur wings to compare?

secondly: thye are similar too. so maybe they was similar also in the genetic level. the dorsal fin of both dolphin and ichthyosaur are similar too. so how do you know thta they not evolved by a convergent evolution in the genetic level?

 

[Speedwell]

first; how do you know? do you have any sequence of a pterosaur wings to compare?

secondly: thye are similar too. so maybe they was similar also in the genetic level. the dorsal fin of both dolphin and ichthyosaur are similar too. so how do you know thta they not evolved by a convergent evolution in the genetic level?

I'm not really sure what your point is. Convergent evolution is the development of similar morphologies from different genetic starting points. Similar morphologies do not imply similar genetics.

 

[xianghua]

I'm not really sure what your point is. Convergent evolution is the development of similar morphologies from different genetic starting points. Similar morphologies do not imply similar genetics.

what do you mean by "different starting points"? there is any rule in evolution that saying we cant get the same sequence by a convergent evolution?

 

[Speedwell]

what do you mean by "different starting points"? there is any rule in evolution that saying we cant get the same sequence by a convergent evolution?

It's not a "rule," it's just extremely unlikely. The reptile genome is not the same as the mammal genome. Why should we assume that if the reptile and the mammal both develop their forelimbs into winglike structures, the underlying genetics should be similar? Even if the morphological structure was very similar (which in this example is decidedly not the case) there would be no reason for that assumption. It's not like they both ordered their wings from the same catalog. They each had to build their wings from material already on hand, and the starting materials were very different.

So what was your point?

 

[xianghua]

It's not a "rule," it's just extremely unlikely. The reptile genome is not the same as the mammal genome. Why should we assume that if the reptile and the mammal both develop their forelimbs into winglike structures, the underlying genetics should be similar? Even if the morphological structure was very similar (which in this example is decidedly not the case) there would be no reason for that assumption. It's not like they both ordered their wings from the same catalog. They each had to build their wings from material already on hand, and the starting materials were very different.

So what was your point?

so lets assume that we found them to be similar also in the genetic level. why it will falsified evolution?

 

[Speedwell]

so lets assume that we found them to be similar also in the genetic level. why it will falsified evolution?

Because of the extreme unlikelihood of it happening. Except for a very, very simple structure where the options for possible genetic underpinning were few (and I can't even think of an example--it would have to be in a simple, single celled organism) it would be all but impossible. For a complex winglike structure there are so many locations in the genome that could or could not be involved and so many possibilities at any of the locations for producing similar structures that even if the structures were morphologically very similar, the odds of the genetics being similar are so vanishingly small as to be entirely negligible. I mean, even if you wound the clock back and let the bat evolve again, and it did evolve identical wings again, the chances of the underlying genetics being the same wouldn't be very good. You could imagine how unlikely it would be if you were starting from two entirley different genomes.

 

[Speedwell]

But perhaps that is not very clear. Consider this analogy: Suppose you gave a kid a set of building blocks of random shapes and sizes, and told him to build a tower two feet tall; then you gave the same blocks and the same instructions to another kid. What is the likelihood that the two towers would have all the same blocks in the same positions?

 

[pat34lee]

Rhetoric =/= evidence.

Come up with something better then. What is science?

 

[The Stamp]

so lets assume that we found them to be similar also in the genetic level. why it will falsified evolution?

Even if you destroyed evolution right now it would not bring you one iota closer to there being a God.

 

[AV1611VET]

Even if you destroyed evolution right now it would not bring you one iota closer to there being a God.

Nor an AV1611VET, nor a Stamp, nor a consol, nor a ...

In other words, what's your point?

 

[The Stamp]

Nor an AV1611VET, nor a Stamp, nor a consol, nor a ...

In other words, what's your point?

Creationists fooling themselves into believing that evolution is the enemy are only wasting their time, creationism is their enemy and always has been, that's my point.
Evolution is used by creationists as the enemy to stop them thinking about how ridiculous their beliefs in creationism are.

 

[AV1611VET]

Creationists fooling themselves into believing that evolution is the enemy are only wasting their time,

Good point.

Evolution isn't the enemy ... Satan is.

 

[TagliatelliMonster]

did you forgot natural selection? if one sequence can evolve once it can evolve twice.

Natural selection can only "select" for the random input it receives.
Natural selection pressures are dictated by all aspects of the habitat the creature finds itself in at the time that it is alive. From climate conditions to virus strains that are around, predators, diet, geological activity, etc etc etc etc.

The amount of variables here are inumerable.
The evolution of a trait also doesn't happen overnight.

It is a long, gradual process... where a mutation is introduced in a single individual, which then survives and passes on its genes. This, however, is by far not the end of the line. The mutation needs to spread into the entire population before it is an integral part of the species. This takes quite a few generations.

Next, it is rather unusual that a trait or function is the result of a single mutation. More often then not, it is multiple mutations working together - most of which come from different individuals.

The amount of variables in this entire process is gigantic.

For that reason, it is completely unreasonable to expect that the exact same genetic sequences would evolve twice independently.

Yes, in theory, it could happen. However, this is SO unlikely that it would pose serious problems for the entire theory. "it could happen in theory" is not a sufficient explanation at all.

 

[xianghua]

Because of the extreme unlikelihood of it happening. Except for a very, very simple structure where the options for possible genetic underpinning were few (and I can't even think of an example--it would have to be in a simple, single celled organism) it would be all but impossible. For a complex winglike structure there are so many locations in the genome that could or could not be involved and so many possibilities at any of the locations for producing similar structures that even if the structures were morphologically very similar, the odds of the genetics being similar are so vanishingly small as to be entirely negligible. I mean, even if you wound the clock back and let the bat evolve again, and it did evolve identical wings again, the chances of the underlying genetics being the same wouldn't be very good. You could imagine how unlikely it would be if you were starting from two entirley different genomes.

ok. so first; if its only similar to bat wings, this case will also falsified evolution?

secondly: where is the limit of convnergent evolution in the genetic level? in about 10 convergent mutations? 20? 50? where is the limit that you will say that evolution have been falsified?.

 

[Speedwell]

ok. so first; if its only similar to bat wings, this case will also falsified evolution?

secondly: where is the limit of convnergent evolution in the genetic level? in about 10 convergent mutations? 20? 50? where is the limit that you will say that evolution have been falsified?.

It would have to be determined on a case-by-case basis. But I am not interested in continuing this discussion unless you tell me what you point is.

 

[The Stamp]

But I am not interested in continuing this discussion unless you tell me what you point is.

His point is to feel that he is arguing his case, he's not but feels justified as long as you keep replying to his rhetoric.
I will leave it there.