When wondering about the origins of our brain, don't look to Homo sapiens, chimpanzees, fish or even worms. Many key components first appeared in single-celled organisms, long before animals, brains and even nerve cells existed. …
The finding is intriguing on its own, but much more significant when combined with a growing body of evidence that essential brain components evolved in choanoflagellates before multicellular life appeared.
In 2008, Xinjiang Cai of Duke University in Durham, North Carolina, discovered that M. brevicollis has the same calcium channels in its cells as those used by neurons. Then, in 2010, it emerged that M. brevicollis also has several proteins that neurons use to process signals from their neighbours.
And this year, Harold Zakon of the University of Texas at Austin and colleagues discovered that M. brevicollis has the same sodium channels that neurons use to pass electrical signals along their length.
Put together, these findings suggest that choanoflagellate cells have components for each of the three main functions of neurons: carrying electrical signals along their bodies, signalling to their neighbours with neurotransmitters, and receiving those signals. …
"The choanoflagellates have a lot of precursors for things we thought were only present in animals," says Fasshauer. Today, says Zakon, the nervous system seems "unbelievably complex", but evidence from these tiny organisms suggests it was built up from several simple systems, which evolved separately for different reasons. For instance, Fasshauer suspects M. brevicollis uses Munc18/syntaxin1 to secrete chemicals, much like neurons use it to release neurotransmitters.
So an ancient, primitive organism just happened to evolve spontaneously incredibly complex molecular machines that would be crucial components in the exquisite neuron designs in multicellular life. It would be like finding jet engine components in a wagon train. It seems that nothing in biology makes sense in the light of evolution.
Dr Hunter might have a point if the Munc18/syntaxin1 complex had no function in choanoflagellates, but it does. As Burkhardt and coauthors wrote in their PNAS paper:
ReplyDeletePrimordial neurosecretory apparatus identified in the choanoflagellate Monosiga brevicollis
"Here we aimed, by comparing the core secretion machinery of the unicellular choanoflagellate Monosiga brevicollis with that of animals, to reconstruct the ancestral function of the Munc18/syntaxin1 complex. We found that the Munc18/syntaxin 1 complex from M. brevicollis is structurally and functionally highly similar to the vertebrate complex, suggesting that it constitutes a fundamental step in the reaction pathway toward SNARE assembly. We thus propose that the primordial secretion machinery of the common ancestor of choanoflagellates and animals has been co-opted for synaptic roles during the rise of animals."
Remember, evolution has no foresight.
The ancestors of birds had limbs and feathers, just like birds. So ...
ReplyDeleteSo an ancient, primitive organism just happened to evolve spontaneously incredibly complex molecular machines that would be crucial components in the exquisite flight designs in birds. It would be like finding jet engine components in a wagon train. It seems that nothing in biology makes sense in the light of evolution.
CH: For evolutionists, these roads lead to the unexpected conclusion of early complexity.
ReplyDeleteFor the umpteenth time, finding something unexpected isn't necessarily the same as finding something that conflicts with the underling explanation behind evolutionary in the first place. Again, finding out primitive people use rocks, rather than sticks when tallying numbers isn't a falsification of the principles of mathematics.
I'd was about to say it's unclear why you'd expect us to never be surprised, however I can think of several reasons why you'd either project such an expectation to your audience or actually hold it personally - neither of which are remotely scientific in nature.
In addition to Pedant's insight, I'd also add that your conclusion is yet another example of how one cannot extrapolate conclusions from observations without first putting them in an explanatory framework.
Specifically, you're assuming these initial components were specifically and intentionally identified to play the particular role they're playing now in neurons. But this isn't clear based on observations alone. Furthermore, you're either unaware of the framework your applying or you're disingenuously attempting to portray your position as being "framework free" in contrast with evolution.
In other words, there are no framework free observations in science. Yet you act as if you're conclusions are somehow pure interpretations of observations.
From your post on Ann Coulter…
CH: Right or wrong, Intelligent design is an appeal to the evidence. And right or wrong, evolution is an appeal to the convictions.
Yet, this entire post clearly isn't merely an appeal to the evidence.
What I can't figure out is if you're too much of a naive empiricist to tell the difference or if you know perfectly well, yet choose to present a falsehood anyway. Given that I've already pointed this out several times, what else do you expect us to conclude if not the latter?
This early complexity is another example of the evolution’s massive serendipity—evolution somehow created designs that would be crucial down the line.
ReplyDeleteYeah, we can't have evolution adding bits and pieces that turn out to be useful at some future date as well. No, no, no. If evolution was true, we would expect everything to pop into existence fully formed. We certainly don't find that! Therefore, evolution is wrong. Cornelius is a genius.
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ReplyDeleteHawks beat me to it. Damn you, slow @$$ iPad editing!
ReplyDeleteWow, just noticed the huge gap in timestamps. Wonder how that happened.
ReplyDeleteAre these proteins found in places other than in mocrobes and brains?
ReplyDeletenatshuster, here's how to answer your question:
ReplyDelete1) Turn on your computer. Connect to the Internet. Open a browser search box. Type "syntaxin1" into the search box. Inspect the links. Click on the links. Read.
2) Turn on your computer. Connect to the Internet. Open a browser search box. Type "munc18" into the search box. Inspect the links. Click on the links. Read.
A cursory search indicates they appear in Jelly fish.
ReplyDeletehttp://jeb.biologists.org/content/203/12/1797.full.pdf
Yet Jellyfish do not have a brain. To quote the paper.
Since the time of Pantin (1952), and as knowledge of these nervous systems has increased, it has become increasingly clear that cnidarian nerves and synapses operate in much the same way as those of higher animals, and the lack of a brain is now seen as an adaptation to radial symmetry rather than an indication of primitiveness (Satterlie and Spencer, 1987).
So, here we have a organism that has a significantly more advanced nervous system than a microbe, but one that is significantly different in that it lacks a brain. In this case, at a minimum, syntaxin 1 appears to play a similar role but in a very un-similar form.
CH: If evolution is true, then it somehow produced incredible feats of engineering early on, even before they would have been useful.
ReplyDeleteBut later quotes from the article..
Put together, these findings suggest that choanoflagellate cells have components for each of the three main functions of neurons: carrying electrical signals along their bodies, signalling to their neighbours with neurotransmitters, and receiving those signals. …
However, each of these components *are* useful in the case of M. brevicollis. Just not in the form of a neuron
Again, this is yet another misrepresentation of evolutionary theory, as it does not suggest earlier uses of these components must play the same role in the future. Rather that they were useful in the process of coping M. brevicollis' genome. That would be your assumption as a creationists.
Should I put this on your ever growing tab of misrepresentations of evolutionary theory which you refuse to address?
Let me guess, you refuse to discuss this misrepresentation because the CSC settled their court case and evolutionists are "liars?"
Pedant:
ReplyDeleteI did as you suggested. I couldn't find any information on whether synapsine 1 is found outside of microbes and animals with neurons. The reason I am asking is because there might be a problem if it isn't fund in an organism situated evolutionarily between microbes and creators with neurons. If they aren't found in things like sponges, then it means they evolved in microbes, hung around as microbes evolved into simple multicellular animals, then were co-opted for use in neurons as animals with neurons evolved, then disappeared from the sponges. Where did they go?
Nat,
ReplyDeleteTry "ion channels Porifera".
Thanks, anaxyrus, you've saved me a lot of typing. natschuster can talk to you from now on!
ReplyDeleteAnother place our friend might look is the report of the complete sequence of a sponge genome:
http://www.nature.com/nature/journal/v466/n7307/pdf/nature09201.pdf