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Origin of species is traced to pond life
The Times of London ^ | TUESDAY DECEMBER 18 2001 | BY MARK HENDERSON, SCIENCE CORRESPONDENT

Posted on 12/18/2001 5:07:16 PM PST by Map Kernow

LONG-LOST relatives of the human race have been traced for the first time. They live at the bottom of puddles. A family of humble microbes has been found to carry a special signalling gene that was previously known only in the animal kingdom. The discovery suggests that the single-celled creatures represent a vital staging post in evolution and that all animal life on Earth descended from something very like them.

The survivor from our ancient ancestors is the collar flagellate or choanoflagellate — a microscopic organism that uses a sperm-like tail to swim through shallow water, grazing on bacteria that lodge in its feeding “collars”.

Its remarkable evolutionary legacy, which stretches back at least 600 million years, has been identified by researchers in the US. Today 150 species of collar flagellates exist around the world, but evolution also gave rise to a more complex lineage that eventually led to the animal kingdom.

“They are the closest nonanimal organism to animals,” said Sean Carroll, Professor of Genetics at the University of Wisconsin-Madison, who led the research. “They are to animals what chimps are to humans, and by studying some of their genetic characteristics, we can begin to make some strong inferences.”

In the study, published today in the Proceedings of the National Academy of Sciences, Professor Carroll and his colleague Nicole King analysed proteins from a species of collar flagellate called Monosiga brevicollis. They located a type of signalling gene, receptor tyrosine kinase (RTK), which sends messages to other genes telling them to become active or making them dormant. It is almost identical to similar version found in animals as diverse as humans and sponges.

The findings support strongly the idea that many genes that animals use today were already in place and available on the eve of animal evolution, but changed in function with the step forward to multicellular organisms with distinct body plans and systems of organs.

The microbes, which measure five thousandths of a millimetre in diameter, are protazoans — simple organisms that were once regarded as animals but are now generally considered to be part of a separate kingdom, the single-celled protists.

Scientists consider the moment at which multi-celled animals, or metazoa, evolved from the protozoans to be one of the turning points in the history of life on Earth. The process is thought to have taken place about 600 million years ago.

“The question is, who were the ancestors of animals and what genetic tools did they pass down to the original animals,” Professor Carroll said. The evolution of the metazoa from the protozoans is one of the milestones in the history of life. To build a multicellular organism compatible with a multicellular lifestyle is something that is very difficult. It takes a lot of genetic machinery to do that, and you have to ask the question, did it all arise when the animals came along, or was some of it in place earlier? “We’re starting to get a glimpse of the genetic tool kit we have in common. In choanoflagellates, we’ve found genes that previously were believed only to exist in animals. It’s a confirmation of the idea that the genes come first, before their exploitation by organisms.”

The study concludes: “We have discovered in M. brevicollis the first RTK, to our knowledge, identified outside the metazoa. The architecture . . . resembles that of RTKs in sponges and humans and suggests the ability to receive and transduce signals. Thus, choanoflagellates express genes involved in animal development that are not found in other eukaryotes (complex organisms), and that may be linked to the origin of the metazoa.”


TOPICS: News/Current Events
KEYWORDS: crevolist
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To: dubyagee
.. Even if evolution were fact, ID is a possibility…. To explore ALL avenues with no set destination is the only way to discover

ID is certainly a possibility, but as Patrick Henry points out in #189, why go there if there is no evidence pointing in that direction? When the evidence points that way science will assuredly follow.
Behe and Dembski go there because they have no evidence. Runnin’ scared, they are.

201 posted on 12/19/2001 5:19:23 PM PST by nimdoc
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Comment #202 Removed by Moderator

To: StewartSmith
Yeah, but fortunately he is appeased by the sweet savour of burnt flesh.
203 posted on 12/19/2001 5:50:51 PM PST by BMCDA
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To: nimdoc
Behe and Dembski go there because they have no evidence

And again I say that to many the laws and the order is evidence. But after reading the last few posts on this thread I think I'll run scared. It's going downhill fast....

204 posted on 12/19/2001 6:01:41 PM PST by dubyagee
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To: pcl
The fact that life in this part of the universe uses left handed amino acids and right handed protiens is a matter of chance.

Well.

Homochirality of life is not likely a matter of chance. There is plenty of evidence which suggests that multiple influences from catalysts, substrates, parity violating weak forces, gamma rays, stability of complexes and so forth influence the energetic advantage of one isomer or enantiomer over another. Just because sugar forms a racemic mixture in your particular reaction doesn't mean that all reactions result in racemic mixtures.

205 posted on 12/19/2001 7:15:56 PM PST by Nebullis
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To: dubyagee
Provides a wonderful glimpse inside the designer's "mind", yes?

There are myriad sucy revealing glimpses from the world of science. If you put them all together, what picture does this "mind" present? Anything approaching current evolutionary theory?

206 posted on 12/19/2001 7:19:26 PM PST by Nebullis
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To: Nebullis
Homochirality of life is not likely a matter of chance.

To what degree is it "not likely."

207 posted on 12/19/2001 7:25:39 PM PST by pcl
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To: pcl
(If we were invaded by life made from mirror image carbon changes, we would not have to worry about them eating us. )

That is good "organic chemistry humor":-)LOL!You should consider that for some text book. cheers

208 posted on 12/19/2001 7:29:58 PM PST by week 71
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To: pcl
You understand, I hope, that epsilon is all it takes.
209 posted on 12/19/2001 7:31:11 PM PST by Nebullis
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To: Nebullis
Homochirality of life is not likely a matter of chance. There is plenty of evidence which suggests that multiple influences from catalysts, substrates, parity violating weak forces, gamma rays, stability of complexes and so forth influence the energetic advantage of one isomer or enantiomer over another. Just because sugar forms a racemic mixture in your particular reaction doesn't mean that all reactions result in racemic mixtures.

My head is swimming with terms from my undergraduate organic chemistry classes! I must say you sound very cerebral, pedantic, and a regular erudite. I hope to never have to argue some point with you. :o)

210 posted on 12/19/2001 7:44:16 PM PST by week 71
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To: nimdoc
But when you go into the realm of the quantum world, things happen without a cause. A number of theories have been put forward that a allow the universe to exist, like a quantum event, without a cause.

Even in the various theories to which you refer, a quantum world is still not absolutely nothing, but a necessary set of physical conditions. Things cannot happen where there is total nothingness because by definition there are no things in total nothingness. A quantum vacuum is not nothing, and fluctuations in a quantum vacuum do not constitute an exception to the principle that whatever begins to exist has a cause. The universe still has to have a source, and appealing to arbitrary necessity by saying that it just happens to exist is not a reasonable or satisfying explanation.

Isn't that the whole point of science anyway; namely, looking for rational reasons for things? Our scientific knowledge about the physical universe is based on our understanding of cause and effect, and it is therefore reasonable to assume that the universe itself has a cause, and so is contingent.

Cordially,

211 posted on 12/19/2001 7:49:32 PM PST by Diamond
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To: Nebullis
Cut to the chase. Are you asserting that the fact that life composed of carbon chains mirroring ours is impossible? Not nearly impossible, or close to impossible, must just plain impossible?
212 posted on 12/19/2001 7:54:06 PM PST by pcl
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To: week 71
I must say you sound very cerebral, pedantic, and a regular erudite.

He is mearly a sesquipedalian. If he were to defenestrate the big words we might be able to have a conversation.

213 posted on 12/19/2001 7:58:52 PM PST by pcl
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To: pcl
Cut to the chase. Are you asserting that the fact that life composed of carbon chains mirroring ours is impossible? Not nearly impossible, or close to impossible, must just plain impossible?

Given a set of conditions with an outcome favorable to L, even with a small advantage, it would eventually rule out R. So, I think it's very possible that ancient conditions were such that both L and R existed, but that one gained an advantage, not by pure chance, but because conditions favored one over the other. Conditions elsewhere in the universe may well tip the advantage to the mirror compounds.

214 posted on 12/19/2001 8:06:29 PM PST by Nebullis
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To: Nebullis
not by pure chance, but because conditions favored one over the other.

The fact that conditions favored one over the other..

Was that not determined by chance?

215 posted on 12/19/2001 8:46:37 PM PST by pcl
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To: patrickhenry
Placemarker.
216 posted on 12/20/2001 2:21:40 AM PST by PatrickHenry
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To: pcl
The fact that conditions favored one over the other.. Was that not determined by chance?

I don't pretend to have anything useful to say about the how it is that the universe is instead of isn't. But this initial state of affairs, for example, is not the immediate reason you turn one way to go to work in the morning instead of the other way. Nor is it the reason for the homochirality of life.

217 posted on 12/20/2001 4:32:44 AM PST by Nebullis
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amend: for this particular homochirality.
218 posted on 12/20/2001 4:33:57 AM PST by Nebullis
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To: Nebullis
Suddenly, I feel less like an individual, and more like a well coordinated lump of coral. What if one group of cells stages a coup? Okay, now I'm paranoid! Hold yourself together, Bach... hold your self togeth... *slough splat*
219 posted on 12/20/2001 4:43:27 AM PST by Wm Bach
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To: week 71
I do agree, most definitely. Sproul's the man!
220 posted on 12/20/2001 4:45:40 AM PST by sheltonmac
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