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Last common ancestor of cold- and warm-blooded species?

Discussion of everything related to the Theory of Evolution.

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Last common ancestor of cold- and warm-blooded species?

Postby delta » Sun Sep 25, 2005 8:11 am

Hello,

recently I saw again the Voyager episode "Distant origin". The background is that there is dinosaur race that developed on earth and later fled to another far-away planet when a big catastrophe was threatening the earth. (You can forget this again, it was just a preamble. :wink: )

In the episode there are some facts mentioned:

1. There was a creature called Eryops which lived in the Devonian Era. This creature, it is stated, probably is the last common ancestor of cold- and warm-blooded creatures. Is this true, probably true, wrong, probably wrong or not known yet?

2. The hadrosaurus is the most advanced cold blooded creature that developed from the Eryops. Again, true, false? Is there a criterion for the degree of advancement?

3. The hadrosaurus could have developed into a complex human like being (or let's rather say primate like being) as it bears some important features like standing upright and having "hands" to grip something. Sure, this is just a hypothesis, but is this completely made up by Star Trek authors? Did anyone seriously think about how dinosaurs would have developed in case they did not die out (and maybe without mammals)? (Is there something like "hypothetical palaeontology"? I'm not talking about fairy tales like Dinotopia.)

4. It is said that the alien dinosaur race and humans have 47 genetic markers in common, as well as humans and the Eryops have. Well, this 47 is a number that often occurs in ST, so it's just made up. But anyway, is there something like a common genetic base which reaches back to creatures from the Devonian age? How about those genetic markes in general? Is this a common way to express the degree of relationship? So if it is... how many markers do have humans and bonobos have in common, and how about humans and mice or humans and crocodiles?

I've looked up a bit of this in wikipedia but could not find satisfiying answers. Do you know another good website for this? I guess I would have to look for "phylogenetic palaeontology" or something? I'd like to learn more about this topic. (But I'm not a biologist... however I have some background in mathematics and philosophy of biology.)
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Postby mith » Sun Sep 25, 2005 1:08 pm

Seems kinda far-fetched that dinos could use interstellar travel....and go all the way to the delta quadrant too.

That said, of course that species originated on earth. Whenever creators of the show create aliens it's almost always similar to humans, bipedal, two eyes, bilateral symmetry.

1.The last common ancestor was supposed to be some sort of rodent-like reptile since early mammals were rodents/marsupials. Also, the eryops was an amphibian that lived in the Permian era, a couple hundred million years after the devonian.

2. That probably meant when it split from its ancestor. It's probably inaccurate to say advanced but better to say "newer specie" or something like that.

3. Yep, I don't remember which steven jay gould book it was, but he stated that if evolution were to happen again, there's a good chance that we might not have evolved. Which makes sense since evolution is more like a drunk trying to go from a sidewalk to a taxicab on the the street than someone going directly.
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Postby MrMistery » Sun Sep 25, 2005 5:40 pm

remember: we only discovered about 1% of the animals that lived on earth!!!

1. depends who you ask. There is a hypothesys that dinosaurs(or at least some of them) were warm-blooded. Anyway, we do not know, and unless we invent time travel i doubt we will ever do.

3. Totally agreed, since evolution is random. I would go even as far as saying that stating such a thing is almost foolish. I liked the analogy, Dave.

4. What do you understand by genetic markers? If you do temperature denaturation followed by renaturation mice and human DNA matches in proportion of 25%. Human and primate- 97%. Human and crocodile, don't know, probably something like 1% if so...
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Postby delta » Sun Sep 25, 2005 8:22 pm

Thanks for the feedback. :)

Originally written by mithrilhack:
Whenever creators of the show create aliens it's almost always similar to humans, bipedal, two eyes, bilateral symmetry.

There is an explanation given in TNG 146 (The Chase). Somewhat disappointing though, all too short, but a nice idea.

idib:
The last common ancestor was supposed to be some sort of rodent-like reptile since early mammals were rodents/marsupials. Also, the eryops was an amphibian that lived in the Permian era, a couple hundred million years after the devonian.

Gee, I thougth they would pay a little more attention on the known facts. Always thought the stress lay more on "science" than on "fiction". :roll: So taking into account also MrMistery's answer that statement made about the last common ancestor is either probably wrong or totally wrong, right?

ibid:
It's probably inaccurate to say advanced but better to say "newer specie" or something like that.

Yes, thought so. I actually was hesitating to write "advanced", that's why I asked for a criterion.

ibid:
Yep, I don't remember which steven jay gould book it was, but he stated that if evolution were to happen again, there's a good chance that we might not have evolved.

Ah, thank you. I've found a book of Gould which deals with this. But can't tell you the English title, only the German. ("Illusion Fortschritt")

Originally written by MrMistery:
What do you understand by genetic markers? If you do temperature denaturation followed by renaturation mice and human DNA matches in proportion of 25%. Human and primate- 97%. Human and crocodile, don't know, probably something like 1% if so...

Actually I am not sure. I was relying on the fact that there is some meaning for "genetic marker". :wink: I looked it up in the Wikipedia but it did not help that much:
Originally written in Wikipedia
A genetic marker is a specific discovered single nucleotide polymorphism or SNP (or simply "mutation") of certain section of DNA of a specific genome. The SNP can either be associated with a known genetic disease, or, it can be in junk DNA that occurs in many individuals and thus be useful for population studies. [...]

I'm more or less familiar (read: heard before) with percentual values to express how similar the genomes of two species are. What puzzles me about this genetic markers is the fact that they always use an absolute number in Voyager -- 47 that is, rather than 47%. It is also said that this number is rather high, i.e. too hight to be just a coincident. But maybe it's again just sloppy star trek science. :lol:
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Postby MrMistery » Mon Sep 26, 2005 6:33 pm

47% That is absurd. Think about it: the rat is a mammal and we only share 25%. But 47 with a reptile? NO no no no....
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Postby delta » Tue Sep 27, 2005 11:16 am

MrMistery wrote:47% That is absurd. Think about it: the rat is a mammal and we only share 25%. But 47 with a reptile? NO no no no....

Of course it is. I was merely refering to the unit. It would still be the same if they had claimed "1 genetic marker in common" Why an absolute quantity and not a percentual value?
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Postby delta » Mon Oct 10, 2005 9:47 am

Sorry for double post but it has been a while... :wink:

@mithrilhack: Thank you for the book of Gould you recommend. I really love it. :D

@all: If you're interested: The original title is "Full House: The Spread of Excellence from Plato to Darwin"
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