I was reading the site Adequacy.org, and ran across this article:



http://www.adequacy.org/?op=displaystory;sid=2001/9/30/172813/212



This is weird. Weird anti-evolution arguments, specially creationist ones, are a dime a dozen, but this one is different, and I don't know how the author is wrong...

How is he wrong?

He isn't peer-reviewed?

:)

Well, skimming the article, his argument is SLIGHTLY flawed. Or, at least, his conclusion is diffrerent than his hypothesis.

Hypothesis: Evolution Theory is not Fully Substantiated
Conclusion: Evolution Theory is wrong.

This is a pretty common logical trick. Most people don't even know they're using it anymore... and I would not be the one to accuse the author of using a logical fallicy to prove logical fallacy... but you do have to appreciate the irony of it.

There was another post, about Shrek. I thought that was an example of "if you're looking for it, you'll see it". That is, if you're expecting a certain attitude, you'll hear it even in innocent phraseology. And to quote a master "And we all know how funny good role models are".

His argument seems be that evolution is not an empirical theory; it can't be proved. This is to a major extent correct; you can't really prove anything about dinosaurs other than they had big bones.



However, the theory of natural selection does make predictions. Not prediction in the sense 'this is what we'll look like in a godzillion years', but 'if Natural Selection is a fact, we'll find evidence of increasing variation as species differ; and that closely related species will have more similar DNA'.



That's not the exact argument so don't try and pick holes in it; it's the best paraphrase I can come up with on the spur of the moment.



My thrust his thus: Natural Selection is the best theory we have. The fact that we're discussing all life means there's no yardstick by which to compare; this doesn't invalidate the theory. It's because of the all-encomapssing nature of life that I don't like the author's linguistic analogies; I don't think they're valid.

Right, rde, and that's wh it's a theory and not a law. Although there are some questions that I have that dont make much sense to me.

Dinosaur->Mammal... ok there's evidence that the dinosaurs might have been warm blooded, but how do you go from no hair to hair all over? Not only that, but no mammary glands to mammary glands?

Tails... humans came from apes who came from monkies which have tails... I don't see the evolutionary disadvantage of the prehensile tail where it would be evolved out. More importantly, babboons have prehensile tails, but live in places with sparse trees... could it be that Monkies and Apes came from two very different ancestors?

Eyes... why do animals only have 2 eyes? Surely there were creatures that had optic sensors all over themselves in the early stages of life. So why did that go into two? Spiders are the only exception to this I can think of... but why arent there any 4-eyed fish? Or any animals that have 360 degree vision...?

Is it possible that there are other mechanisms working in addition to evolution? Maybe DNA has more encoded information than we thought, including short-range traits, and long-range traits which are activated under certain conditions.

Originally posted by Riomacleod
Right, rde, and that's wh it's a theory and not a law. Although there are some questions that I have that dont make much sense to me.

Dinosaur->Mammal... ok there's evidence that the dinosaurs might have been warm blooded, but how do you go from no hair to hair all over? Not only that, but no mammary glands to mammary glands?

Tails... humans came from apes who came from monkies which have tails... I don't see the evolutionary disadvantage of the prehensile tail where it would be evolved out. More importantly, babboons have prehensile tails, but live in places with sparse trees... could it be that Monkies and Apes came from two very different ancestors?

Eyes... why do animals only have 2 eyes? Surely there were creatures that had optic sensors all over themselves in the early stages of life. So why did that go into two? Spiders are the only exception to this I can think of... but why arent there any 4-eyed fish? Or any animals that have 360 degree vision...?

Is it possible that there are other mechanisms working in addition to evolution? Maybe DNA has more encoded information than we thought, including short-range traits, and long-range traits which are activated under certain conditions.

Hi there, i am new here, so I am gonna just wade right in. :)

There are two answer to the first question. One is that random mutation plays a role, and the other is that we really don't know yet.

Tails: I don't think there is any insistence that it be a "disadvantage" in order to be lost as a trait. One idea is that is you have some appendage that does not get used much, over time it will get smaller and smaller and eventually disappear. Some say that this is happening right now in humans with our pinkies. As for why baboons still have their tales. Easy answer: They haven't caught up yet. There is no reason to assume evolution would move at the same rate for every species.

Eyes: Most animals on the planet have 2 eyes. Possible reasons? Binocular vision. Having 4 eyes might give you a wider field of vision, but you would need a more sophisticated visual processing center inb the brain to handle it. The same goes, to even a greater degree, with 360 degree vision. It might be advantageous, but would the advantages be worth cost. Seems like a trade off between efficiency, speed, and probably other factors we have not even fathomed yet.

Originally posted by Riomacleod



Dinosaur->Mammal... ok there's evidence that the dinosaurs might have been warm blooded, but how do you go from no hair to hair all over? Not only that, but no mammary glands to mammary glands?



For a start, mammals didn't evolve from dinosaurs; evidence suggests they diverged long before. However, WRT the scales->fur: in colder weather, any fur would be an advantage if it kept you even slightly warmer. If that's why it evolved in the first place. Feathers first appeared on dinosaurs for reasons unrelated to flight; speed on the ground and warmth are two possiblities.



Mammaries: again, oviviparous animals evolved separately from our mammalian ancestors; in once case, the egg built up with its own source of nutrition - the yolk - and in another, that nutrition was provided both in the womb and through the mammary glands. These would have been incredibly rudimentary in the early days; only millions of years later did they become so efficient.








Tails... humans came from apes who came from monkies which have tails... I don't see the evolutionary disadvantage of the prehensile tail where it would be evolved out. More importantly, babboons have prehensile tails, but live in places with sparse trees... could it be that Monkies and Apes came from two very different ancestors?
It's not a question of disadvantage as much as cost; a prehensile tail has its purposes, but when you're running for your life in the savannah, it's not much use. As it became less useful, individuals who had smaller tails would need less energy to 'feed' it, and in times of sparse food would have a slight advantage.








Eyes... why do animals only have 2 eyes? Surely there were creatures that had optic sensors all over themselves in the early stages of life. So why did that go into two? Spiders are the only exception to this I can think of... but why arent there any 4-eyed fish? Or any animals that have 360 degree vision...?





Again, look at the cost. Not just in terms of eye-building, but in terms of the brain power needed to process all these extra data.







Is it possible that there are other mechanisms working in addition to evolution? Maybe DNA has more encoded information than we thought, including short-range traits, and long-range traits which are activated under certain conditions. I don't think so. All dna is, basically, short-range traits; most of it would be useless in different conditions. However, for long-range traits, you have again to look at the cost; it's more efficient to have a compact genome rather than one with lots of stuff that may be needed some day. This, BTW, is one of the reasons I'm not convinced that there's so much junk DNA in our genome as most people think.

This looks like a good thread!

Welcome to Sciforums, Northwind and sylvain.

I would add my 2¢ here I believe.



Just because dinosaurs being warm blooded would solve the problems that our modern day archologists have cold bloodedness with does not mean that they have to be mammalian and have mammary glands. Chickens and birds are closer relatives to the dinosaurs than are man. They are also warm blooded.

Nor does this warm bloodness mean that they have to have hair. We are not even sure of what colors that dinosaurs may have been. Were they like male birds of today and more brightly colored than the female of the species? Was their skin leathery? Coarse or supple?

In the case of eyes, it is dependant upon what nature decieded was to be best advantage. Bees have compound or multiple eyes. Good for seeing movement but not for detail. Spiders are much the same with a little better ability in the detail area. Our eye design seems to be good for general purpose. Color, preceptive range, fine detail, movement, slight side vision but not quite 180°. Eagles have extremely good distance vision.

Tails are one of those things we no longer have a use for. We do not spend a great amount of our time in trees. As such there is no use for them. However in the stages of growth of the fetus there is the stage where the tail is to be seen.

Redundant dna may have a purpose. It saves nature from having to redesign along with the random mutation. I would imagine that there is a conservation of energy expeniture along with survival factor within the keeping of old dna.

One idea is that is you have some appendage that does not get used much, over time it will get smaller and smaller and eventually disappear.

The mutation has to be in the DNA first. If it leads to the organism reproducing better than an organism without it, it will become the dominant one.

The above is Lamarkism I believe. A classic example of this flawed theory is that the Giraffe got its long neck by streching to reach higher and higher leaves.

Wet1:
I think you misunderstood my question...
I wasn't implying that dinosaurs were mammals. I'm just fuzzy on where the line is where creatures started randomly growing hair, and between mammary glands and no mammary glands. Especially the mammary thing, because it seems like there's not much in the way of intermediate forms in between giving milk or not. I guess it seems like in this instance there's a little bit taken for granted? I dunno.

Originally posted by Riomacleod



[BEspecially the mammary thing, because it seems like there's not much in the way of intermediate forms in between giving milk or not. I guess it seems like in this instance there's a little bit taken for granted? I dunno. [/B]This is the same same argument anti-evolutionary people used, albeit with the eye instead of the mammary glands.



Consider the mammary glands to be an extention of the womb; one that works after birth. When the first mammal to feed its live offspring did so, it didn't have anything as near a level of sophistication as today's animals. It may not have been milk; it may have been the same substances that feed the foetus in the womb. It may not have had its own glands; they could've come later.







My point is thus: I'm not sure how it works. The fact that I can't explain every aspect of the theory, though, doesn't invalidate it in my mind. Although the theory can be expressed quite simply - 'natural selection' encapsulates it nicely - the mechanics by which it works are vastly complex. You shouldn't dismiss the theory because you don't understand one aspect.

I'm not arguing against it... mine is the voice of pure ignorance of some aspects of evolution :)

These critters might be the precursers to mammals with fully developed mammary glands.

<a href=http://www.healthsci.utas.edu.au/physiol/mono/Monotremata.html>http://www.healthsci.utas.edu.au/physiol/mono/Monotremata.html</a>

On the site, it said that they are a breakaway from the mammal line.

From my link.

However, most scientists believe monotremes are the last survivors of a group of early mammals evolved independently of the creatures that gave rise to today's marsupials and other mammals


The way I read this is that monotremes did not evolve in the same direction as the other mammals, though both had the same common ancestor.

So while other mammals went on to develop the mammary glands common today, there was no enviromental pressure, to utilise any mutation, for monotremes to go down this track.

*grins*
Well, I'm still going to work on evolving a tail.:D