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.”
Easy. Being an 18-year-old male and giving up front row seats at a Britney Spears concert.
Sure you are, at least by implication. Your position (as defined by your question) boils down to a statement on that there is no Creator. By ruling out same, you lay claim to some superior knowledge as to the actual source of the universe.
My position as not that there is no Creator.
My position is that there is no evidence to support the existence of one.
I've read with interest your comments on this thread and just thought I'd let you in on the secret.
I'm God. yup thats right . I made all this , brought everything into being myself. Your just a part of my story,you only exist in relation to me. I know thats a bit hard to swallow but hey, it's gotta start somewhere , right ?
Easy. Being an 18-year-old male and giving up front row seats at a Britney Spears concert.
That would only hurt for a few weeks or a month or two; being an idiot hurts for life. Ask some of the evolutionists about it.
Don't make me come down there.
Maybe. But that would mean that the universe is non-contingent, i.e., uncaused. And everything about the physical universe that we know tells us that it is contingent because everything in the physical universe depends upon a prior cause.
Cordially,
I don't believe you. Your posts on the topic are not consistent with that position.
Your disbelief is a matter of complete indifference to me.
Interesting way to look at things. If science doesn't explain absolutely everything to your satisfaction, you seem to reject it all, entirely. On the other hand, divinities are unsupported by evidence and they explain nothing at all; yet you claim that they give you the answers to everything.
LOL! I rather expected that response. Nevertheless, your statement of "no evidence" is belied by your posts, and that's something you probably ought to address.
It's pretty familiar territory -- I recognize the statement from the days when I was running away from God.
No, that's not at all what I said, as you well know. Nor do I "reject all science, entirely."
On the other hand, divinities are unsupported by evidence and they explain nothing at all;
Oh, my. That's a completely insupportable statement.
yet you claim that they give you the answers to everything.
Nor do I make that claim.
I make that two gross mischaracterizations and one insupportable statement. Not a single useful thing in that post. Perhaps you should try again.
Unsatifstying, perhaps. But also either necessary or impossible, because a contingent universe that is uncaused is logically contradictory.
If there is total nothingness than there could never be anything. The fact that something, anything, exists means that something must have always existed. Therefore being has to be and is necessary.
But in the Godless universe scenario, the possibility of total nonexistence is a viable option to existence, because in that scenario the universe is accidental and could just as easily not come to be. If the universe could fail to be then it is not a necessary universe. So the question then for the atheist is, how could a contingent state of affairs produce a universe in which being has to be? I do not have a satisfying answer to that.
Cordially,
She was a wonderful Lady.
When I asked her who had made God, she told me that the devil was talking to my mind. I was 5.
That was good. I notice that nobody even attempted to refute it.
Note to Santa Claus: new keyboard
You replied: Oh, my. That's a completely insupportable statement.
In what way is it insupportable? I'm very open-minded to evidence and logical argument.
What archeological study shows the world was created in six days?
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