Tuesday, June 15, 2010

Brown Algae and The Serendipity of Multicellularity

The genome of Ectocarpus siliculosus, a brown algae, has been sequenced and analyzed. As usual the evolutionary model fits about as well as the flat earth theory. Evolutionists claim their theory is crucial for predicting the contents of such newly sequenced genomes. But in practice we see a different story. Most obvious are the many differences found between allied species. The E. siliculosus genome is no different in this regard:

Analysis of the Ectocarpus genome failed to detect homologues of many of the enzymes that are known, from other organisms, to have roles in alginate biosynthesis and in the remodelling of alginates, fucans and cellulose, indicating that brown algae have independently evolved enzymes to carry out many of these processes.

[…]

For example there are several additional membrane-localized proteins of interest, including three integrin related proteins. Integrins have an important role in cell adhesion in animals but integrin genes are absent from all the previously sequenced stramenopile genomes. The Ectocarpus genome also encodes a large number of ion channels, compared to other stramenopile genomes. These include several channels that are likely to be involved in calcium signalling such as an inositol triphosphate/ ryanodine type receptor (IP3R/RyR), four 4-domain voltage-gated calcium channels, and an expanded family of 18 transient receptor potential channels. Members of all these classes are found in animal genomes but are absent from the genomes of land plants. No IP3R genes have been identified in the sequenced diatom and oomycete genomes, but the presence of an IP3R in Ectocarpus is consistent with the demonstration of ‘animal-like’ fast calcium waves and inositolphosphate-induced calcium release in embryos of the brown alga Fucus serratus.

In all E. siliculosus has close to ten thousand ORFans, something evolutionary theory predicted did not exist. But beyond these massive differences between cousins, The E. siliculosus genome further elucidates evolution’s tale of multicellularity.

Instead of the expectation that multicellularity arose once and then proliferated, evolutionists now must say it arose independently several times. And instead of a sort of primitive multicellularity emerging and then undergoing evolutionary refinement, we must believe evolution first produced profoundly unlikely molecular machines, which then in turn enabled multicellularity.

Animal tyrosine and green plant serine/threonine receptor kinases form two separate monophyletic clades, indicating that these two families evolved independently, and in both lineages the emergence of receptor kinases is thought to have been a key event in the evolution of multicellularity. The Ectocarpus receptor kinases also form a monophyletic clade, discrete from those of animal and green plant receptor kinases, indicating that the brown algal family also evolved independently.

In other words, evolution just happened to evolve intricate machines that then were crucial in evolving a major new innovation—multicellularity. I guess we’re living in the right multiverse.

61 comments:

  1. You might find this bit interesting Dr. Hunter:

    How many different cells are there in complex organisms?
    Excerpt: The nematode worm Caenorhabditis elegans, the cellular ontogeny of which has been precisely mapped, has 1,179 and 1,090 distinct somatic cells (including those that undergo programmed cell death) in the male and female, respectively, each with a defined history and fate. Therefore, if we take the developmental trajectories and cell position into account, C. elegans has 10^3 different cell identities, even if many of these cells are functionally similar. By this reasoning, although the number of different cell types in mammals is often considered to lie in the order of hundreds, it is actually in the order of 10^12 if their positional identity and specific ontogeny are considered. Humans have an estimated 10^14 cells, mostly positioned in precise ways and with precise organization, shape and function, in skeletal architecture, musculature and organ type, many of which (such as the nose) show inherited idiosyncrasies. Even if the actual number of cells with distinct identities is discounted by a factor of 100 (on the basis that 99% of the cells are simply clonal expansions of a particular cell type in a particular location or under particular conditions (for example, fat, muscle or immune cells)), there are still 10^12 positionally different cell types.
    http://ai.stanford.edu/~serafim/CS374_2006/papers/Mattick_NRG2004.pdf

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  2. Dr Hunter:

    In all E. siliculosus has close to ten thousand ORFans, something evolutionary theory predicted did not exist.

    You are referring to the data in Fig. 3 of the paper, where ORFans are identified by comparisons among distantly related organisms.

    Please cite one or more references quoting predictions that such ORFans did not or could not exist among distantly related organisms.

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  4. I'm honestly at a loss to understand what CH thinks he's accomplishing with these ridiculous anti-science rants. Is he just pandering to his tiny number of IDC followers to drive up his blog traffic? Trying to create a fake conflict like Jerry Springer?

    It's hard to see how anyone could believe the nonsense he's been spewing in the last few months. Still, no one ever lost money by underestimating the intelligence of the IDC crowd.

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  5. "thousand ORFans, something evolutionary theory predicted did not exist. But beyond these massive differences between cousins."

    Practically, if you have 1 sequenced genome everything is an ORFan. If you have 2, only the overlapping sequences are not ORFans. Considering the nearest genomes in Fig 3 are of diatoms and oomycetes, which are separated by long long times for evolution to act on, this is a surprise? Sequence another brown algae, and you'll find very few ORFans.

    Evolution predicts and observes the evolution of new features.

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  6. What RobertC said. They are apparently comparing brown algae to very distant genomes -- fungi and animals are closer to each other than brown algae and fungi.

    As for "evolution predicts multicellularity evolved once", that's just silly. Every discussion I've ever read has said that multicellularity evolved dozens of times, basically because it appears in dozens of different groups that have both single-celled and multi-celled species -- groups as diverse as bacteria, fungi, various algaes, etc. If evolution can do something once it can do it multiple times -- it's just very unlikely that it will do it via the exact same molecular path for anything very complex. Thus you will have different branches of a protein family useful for sticking cells together (which is how you get the beginning of multicellarity) utilized by different groups. Etc.

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  7. NickM: "If evolution can do something once it can do it multiple times "

    Who is Evolution that can do something and learn how to do it multiple times?

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  8. "NickM: "If evolution can do something once it can do it multiple times "

    Who is Evolution that can do something and learn how to do it multiple times? "

    'It looked at them and said, "With God this is impossible, but with Evolution all things are possible'
    Book of evolution 19:26

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  9. Blas said...

    NickM: "If evolution can do something once it can do it multiple times "

    Who is Evolution that can do something and learn how to do it multiple times?


    Evolution isn't a 'who', it's an observed naturally occurring process that causes populations of animals to change their genetic makeup over time. It doesn't 'learn', any more than gravity caused downhill flowing water 'learns' to erode channels into bedrock.

    Isn't there a single one of you IDCers out there with the faintest clue on this science stuff?

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  10. Thorton "Isn't there a single one of you IDCers out there with the faintest clue on this science stuff? "

    Tell to NickM to use proper scientific vocabulary and not to talk like evolution is an intelligent been.

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  11. Blas,

    It was you who chose to insert the word 'learn.'

    The initial statement:
    "If evolution can do something once it can do it multiple times."

    Merely states that if something is evolvable, it is evolvable more than once. Convergent evolution is an example, and is hardly controversial.

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  12. Thornton, I posted something for you under the whales post earlier this month.

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  13. Blas said...

    Thorton "Isn't there a single one of you IDCers out there with the faintest clue on this science stuff? "

    Tell to NickM to use proper scientific vocabulary and not to talk like evolution is an intelligent been.


    NickM does use proper scientific vocabulary. You seem to be the one who is ignorant of and confused by what the terms actually mean.

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  14. Fil said...

    Thornton, I posted something for you under the whales post earlier this month.


    OK Fil, I looked and responded.

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  15. Dr. Hunter,

    Why did you pull quotes instead of discussing the evidence? Do real scientific review articles pull quotes? If so, what proportion of them do? For example, do any of the News and Views reviews in this issue of Nature quote the way you do, or do they discuss the evidence?

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  17. Thorton:
    Isn't there a single one of you IDCers out there with the faintest clue on this science stuff?

    Seeing IDC only exists in the minds of the willfully ignorant, they just aren't any IDCers.

    And Thorton doesn't even have the faintest clue about his position!

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  18. Is there any evidence that multicellularity can evolve?

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  19. If some phenomenon X is described as capable of Y, Blas and others here interpret that to be teleological language. Very interesting.

    For example, if someone said "If X-rays can do something once they can do it multiple times", Blas might so-cleverly ask, "Who are these X-rays?"

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  20. thornton: you are truly hapless, witless and inane & know precisely nothing of science but you sure think you do!

    That is what makes you such a sad "why should CH bother to answer this poor ignorant fellow?" case.

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  21. Gary said...

    thornton: you are truly hapless, witless and inane & know precisely nothing of science but you sure think you do!

    That is what makes you such a sad "why should CH bother to answer this poor ignorant fellow?" case.


    Strangely enough though, I'm the guy who keeps providing links to research from the primary scientific literature and offering to discuss the details, while you're the guy who just blusters then runs away.

    Why is that Gary? Why do you run crying from the room whenever a request for technical details about ID arises?

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  22. Joe G asks:"Is there any evidence that multicellularity can evolve?"

    Yes, there's a lot. The basal organisms in metazoa (i.e. multicellular animals) are the Porifera, the order containing the sponges. Porifera act much more like an agregation of cells than an organism. They lack large numbers of specialised cells like more derived lineages such as the mammals and they lack organs.

    While sponges live in a multicellular agregation with 3 differentiated cell types, the cells are fairly independent. More than a century ago, it was demonstrated that sponge cells of a living sponge can be separated using a fine sieve without killing the organism. In fact, several sponges of the same species can be sieved into a pool of sea water and the cells re-aggregate to form new sponges.

    ALso, the green algae of the family Volvocaceae have several types of multicellularity and are closely relate to unicellular algal species. Volvox form small colonies of cells that provide interesting studies of the origins of multicellular life.

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  23. I was wondering how long it would be until someone brought up volvox colonies.

    Many from one: Lessons from the volvocine algae on the evolution of multicellularity
    Commun Integr Biol. 2009 Jul–Aug; 2(4): 368–370.

    "Abstract: The volvocine green algae are a model system for the evolution of multicellularity and cellular differentiation. A combination of molecular genetic and phylogenetic comparative approaches has resulted in a detailed picture of the transition from single cells to differentiated, multicellular organisms in this group. To be useful as a model system, the volvocine algae should provide information that is relevant to other groups. Here I discuss recent advances in understanding the origins of multicellularity and cellular differentiation in the volvocine algae and consider the implications for such transitions in general. Several general principles emerge that are relevant to the origins of major multicellular groups, such as animals, plants, fungi, red and brown algae. First, if the lessons learned from the volvocine algae can be generalized to other origins of multicellularity, we should expect these transitions to be understandable as a series of small changes, each potentially adaptive in itself. In addition, cooperation, conflict and mediation of conflicts among cells are likely to have played central roles. Finally, we should expect the histories of these transitions to include parallel evolution of some traits, periods of relatively rapid change interspersed with long periods of stasis, and simpler forms coexisting with more complex forms for long periods of time as in the evolution of the volvocine algae."

    Of course ID predicted all of this.

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  24. Is there any evidence that Joe G has a brain?

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  25. Dr. Hunter,

    I wonder if you might take the time to apply the same fine skills of criticism you apply to evolutionary biology to one of your own.

    You see, scordova has posted on UD that a program that visualizes patterns "enables us to see the architecture that more resembles premeditated very-large-scale-integrated structure." Now, it is very obvious that patterns are distinct from design*, and indeed, there is no mention of design, or "premeditation" anywhere in the paper. So, it seems he has jumped to a quite strong conclusion without data.

    * http://www.maion.com/photography/namibia/sand_dunes_p31.html

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  26. Is there any evidence that multicellularity can evolve?"

    Paul:
    Yes, there's a lot. The basal organisms in metazoa (i.e. multicellular animals) are the Porifera, the order containing the sponges. Porifera act much more like an agregation of cells than an organism. They lack large numbers of specialised cells like more derived lineages such as the mammals and they lack organs.

    As far as anyone knows Porifera have always been Porifera.

    What evolved and how do you know?

    While sponges live in a multicellular agregation with 3 differentiated cell types, the cells are fairly independent. More than a century ago, it was demonstrated that sponge cells of a living sponge can be separated using a fine sieve without killing the organism. In fact, several sponges of the same species can be sieved into a pool of sea water and the cells re-aggregate to form new sponges.

    True, so what evolved?

    ALso, the green algae of the family Volvocaceae have several types of multicellularity and are closely relate to unicellular algal species. Volvox form small colonies of cells that provide interesting studies of the origins of multicellular life.

    Again as far as everyone knows Volvox have always been Volvox.

    What evolved?

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  27. Volvox- two types of cells.

    Multi means many...

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  28. Thorton:
    Why do you run crying from the room whenever a request for technical details about ID arises?

    Forst go change your diaper.

    Next why is that you have never provided any technical details for your position?

    It is the failure of you and your ilk to support the claims of your position that has allowed ID to persist.

    I take that bothers you so you have to flail away at ID.

    Go change your diaper and be sure to use diaper rash cream...

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  29. Thorton,

    Change your diaper.

    You should also change your spewage.

    But that ain't happenin' is it?

    However your low IQ, sloped fore-head, slouched posteur, and brutish/ childish behaviour are evidence of what happens when genetic accidents accumulate.

    You should be proud...

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  30. As for the internet tough guy schtick- why did you link to your picture?

    IOW your projection is duly noted...

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  31. RobertC:
    I wonder if you might take the time to apply the same fine skills of criticism you apply to evolutionary biology to one of your own.

    That is exactly what I have been telling evolutionists for decades.

    When Anthony Flew finally got around to doing so we all know what happened...

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  32. "When Anthony Flew finally got around to doing so we all know what happened..."

    What happened? He died shortly after a ghostwritten book bearing his name that changed few minds came out? No seriously-inform me what we all know happened.

    Flew has no bearing on my point that is that there is serious hypocrisy-where no data from evolutionary biology is good enough for Dr. Hunter, and his peers get away with howlers like implying pattern and design are synonymous.

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  33. When Anthony Flew finally got around to doing so we all know what happened...

    RobertC:
    What happened?

    He changed his position on ID- he said it was supported by the scientific data.

    And the (ahem) "data" you have shouldn't be good enough for any serious science investigator.

    And no, we do not imply pattern and design are synonymous.

    snowflakes have a pattern- ABABABABABABABABABABABAB- is a pattern.

    Only when the pattern is coupled with a low probability- ie meaning mother nature cannot account for it- do we infer design.

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  34. "Only when the pattern is coupled with a low probability- ie meaning mother nature cannot account for it- do we infer design."

    And there's the howler. You only calculate the odds of a mature protein, or pathway, or organism poofing out of nothingness. You never (and can't) calculate the probability when you actually consider evolution.

    Since we know complexity increases with selection acting on random variation, ID is bunk.

    What we see more often is the insinuation, based on no data, that something patterned or complex must be designed. Why don't you ask Sal why he doesn't provide his probability calculation on the front page of UD, along with the post where he shouts ID has won because of a program that displays patterns??

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  35. Joe G said...

    And no, we do not imply pattern and design are synonymous.

    snowflakes have a pattern- ABABABABABABABABABABABAB- is a pattern.

    Only when the pattern is coupled with a low probability- ie meaning mother nature cannot account for it- do we infer design.


    And we all know you have no way of calculating any actual probability for a biological entity, despite all the empty rhetoric and hot air spewing.

    Determining an after-the-fact specification in no way gives you any indication of how many before-the-fact possibilities there were. Without both sets of data, you can't compute probabilities.

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  36. p.s. If you could calculate these probabilities, you could tell us what is designed and not designed. But even Dembski says he's ID doesn't do that.

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  37. RobertC:
    And we all know you have no way of calculating any actual probability for a biological entity, despite all the empty rhetoric and hot air spewing.

    Sure we do.

    All we have to do is determine the minimal complexity required.

    However we all you don't have any methodology to determine that blind, undirected processes can account for living organisms.

    If you could calculate these probabilities, you could tell us what is designed and not designed.

    It's not just about probabilities.

    And to refute any given design inference all you have to do is demonstrate that mother nature can account for it.

    But even Dembski says he's ID doesn't do that.

    Reference please- Dembski is the guy who has provided to work that is supposed to do just that...

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  38. Oops part of my response was to the baby who needs a diaper change...

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  39. RobertC:
    Since we know complexity increases with selection acting on random variation, ID is bunk.

    Complexity isn't the issue.

    There isn't any data which demonstrates blind, undirected processes can produce a biological organism nor complex protein machinery.

    And agin if you don't like the design inference all you ahve to do is to actually start producing positive evidence for blind, undirected processes.

    Your continued negative attacks on ID do not constitute positive evidence for your position.

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  40. Joe G said...

    Thornton:
    And we all know you have no way of calculating any actual probability for a biological entity, despite all the empty rhetoric and hot air spewing.

    Sure we do.

    All we have to do is determine the minimal complexity required.


    Then do it internet tough guy. Calculate the probability that the particular set of proteins we see is the only possible way for life to occur. Show your work.

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  41. RC: But even Dembski says he's ID doesn't do that.

    JoeG: Reference please- Dembski is the guy who has provided to work that is supposed to do just that... "

    You'd think so, wouldn't you. Sadly, for you ID folks this is completely false.

    In Dembski's words:

    "As I’ve said (till the cows come home, though Thomist critics never seem to get it), the explanatory filter has no way or ruling out false negatives (attributions of non-design that in fact are designed). I’ll say it again, ID provides scientific evidence for where design is, not for where it isn’t."

    http://www.uncommondescent.com/intelligent-design/does-id-presuppose-a-mechanistic-view-of-nature/

    ++++++++++++++++++++++++++++++++++++++++++++++++

    JoeG: There isn't any data which demonstrates blind, undirected processes can produce a biological organism nor complex protein machinery.

    False: Here are gain-of-function from selection acting on random input. Yeah, the empirical falsification of ID:

    Natural:

    http://www.plantcell.org/cgi/content/short/14/12/3149

    http://cancerres.aacrjournals.org/cgi/content/full/68/21/8928

    http://www.sciencemag.org/cgi/content/abstract/281/5377/710

    http://www.newscientist.com/article/dn13673-evolution-myths-mutations-can-only-destroy-information.html

    http://genesdev.cshlp.org/content/20/19/2728.full
    http://atvb.ahajournals.org/cgi/content/full/25/10/2018

    http://www.jstor.org/stable/20205905

    http://atvb.ahajournals.org/cgi/content/full/26/6/1236

    A cool directed evolution type experiment-random domain shuffling yields new interesting phenotypes from novel signaling pathways following selection:

    Rapid diversification of cell signaling phenotypes by modular domain recombination.
    Peisajovich SG, Garbarino Science. 2010 Apr 16;328(5976):368-72.JE, Wei P, Lim WA.

    If you are interested in more, google 'directed evolution' for a ton more along these lines-where human made random variation + selction -> new function.

    Genetic Algorithms produce similar results.

    "Information" from randomness if you will.

    ++++++++++++++++++++++++++++++++++++++++++++++++

    So on one hand we have an admitted inability to detect design from non-design. On the other, we have direct observations and demonstrations of complexity resulting from selection acting on variation. That's not supposed to happen, right?

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  42. Joe G: Next why is that you have never provided any technical details for your position?

    Paul and Thorton have given numerous pertinent examples of organisms at varying degrees of multicellularity. The best you've given in response is the usual anti-evolutionist huffing that "it's still a [whatever]".

    Joe, "Volvox" and "Porifera" are just names. Organisms don't come with names printed on their collars; we give them names, arbitrarily.

    Is it correct to say "wolves have always been wolves"? In a sense, no, and in a sense, yes. It depends on whether you consider dogs, who descend from wolves and (mostly) can interbreed with them, to also "be" wolves. But this is arbitrary. There is clearly a large amount of change from one canine to another, regardless of whether anything is "still" whatever.

    Single-celled and multi-celled creatures make gradual shifts in complexity over the eons. One can always broaden one's definition, of course, so that evolution so powerful that the name of the species actually changes ( :p !) still hasn't occurred. You can say "as far as I know, plants have always been plants".

    What's the magic cutoff line that prevents large amounts of change? There isn't one.

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  43. Joe G says:"As far as anyone knows Porifera have always been Porifera...as far as everyone knows Volvox have always been Volvox."

    I'm not sure I understand your argument here - you asked for evidence that multicellularity can evolve, not evidence that Volvox evolved from obligate unicellular species.

    In line with what you asked, I have given you a couple of examples of intermediate multicellularity where cells aggregate but exhibit far less interdependency than in the more derived metazoan lineages. This demonstrates avenues for how multicellularity can evolve, as you asked.

    Porifera could have always been Porifera only in the sense that the evolution of these clades is ancient and obviously predates direct human observation. The argument for evolution in general is related to numerous, independent lines of reasoning about the most parsimonious explanations for various observed patterns. As such, this argument is too long to write here, and I'm sure you've heard some or most of it before anyway. From the perspective of an evolutionary ecologist, the evidence is strong; from your perspective the evidence is apparently not strong. Fine. However, that was not your question.

    "Volvox- two types of cells. Multi means many..."

    Again, your reasoning is unclear. Multicellularity refers to an organism comprising multiple cells, not multiple cell types, although this is of course common.

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  44. Paul:
    I'm not sure I understand your argument here - you asked for evidence that multicellularity can evolve, not evidence that Volvox evolved from obligate unicellular species.

    Right- what evolved Paul?

    In line with what you asked, I have given you a couple of examples of intermediate multicellularity where cells aggregate but exhibit far less interdependency than in the more derived metazoan lineages. This demonstrates avenues for how multicellularity can evolve, as you asked.

    Again you didn't tell us what evolved.

    Multicellularity refers to an organism comprising multiple cells, not multiple cell types, although this is of course common.

    So a colony is multicellular?

    What evolved?

    But anyway then this conversation is meaningless.

    My apologies-

    I should have asked about metazoans, not multicellularity...

    My bad

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  45. There isn't any data which demonstrates blind, undirected processes can produce a biological organism nor complex protein machinery.

    RobertC:
    False: Here are gain-of-function from selection acting on random input. Yeah, the empirical falsification of ID:

    Natural:

    http://www.plantcell.org/cgi/content/short/14/12/3149


    You have serious reading issues.

    I didn't ask for a gain or function mutation.

    There isn't any data which demonstrates blind, undirected processes can produce a biological organism nor complex protein machinery.

    What part of that don't you understand?

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  46. Hey diaper-boy thorton,

    Why has teh RNA world been posited?

    Because DNA is too complex to have come first- evolutionary biologists figured that out.

    Use their math.

    The same goes for eukaryotes- proks had to have come first because euks are just too complex- improbability.

    Again use the EB math...

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  47. I said:"I'm not sure I understand your argument here - you asked for evidence that multicellularity can evolve, not evidence that Volvox evolved from obligate unicellular species."

    To which Joe G replied:"Right- what evolved Paul?"

    Implicit in your original question was doubt that the gulf between unicellular life and multicellular life could have been bridged by naturalistic evolution, presumably because it appears too large.

    I have attempted to provide some evidence from extant species of observable intermediate stages that demonstrate, upon closer inspection, the gulf is somewhat smaller than it may first appear if only considering the apparent complexity of metazoans on the one hand, and the apparent simplicity of unicellular life on the other.

    What you have not done in either of your replies is give any indication of whether you see the gulf bridged in any way at all by extant species in an intermediate of multicellularity or not. If not, there is little point in discussing this any further.

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  48. Paul,

    It appears multicellularity has been around for as long as living organisms have been around.

    Implicit in my original question is the doubt that anything evolved.

    IOW it appears that forming colonies was part of the make-up of the original population(s).

    IOW my position is that multicellularity- as in forming colonies and even the Volvox is that nothing evolved- that the organisms had the ability to do so from the start.

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  49. This comment has been removed by the author.

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  50. Joe G said...

    Paul,

    It appears multicellularity has been around for as long as living organisms have been around.


    Clueless Joe G is clueless once again.

    The oldest known multicellular animals date to the early Ediacaran period some 610-630 million years ago. There is some evidence (trace fossil tracks) that they possibly arose a few hundred million years earlier.

    The oldest known unicellular life dates back to 3.5 billion years.

    But what's a few billion years to an IDiot like Joe?

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  51. Thorton:
    The oldest known multicellular animals date to the early Ediacaran period some 610-630 million years ago. There is some evidence (trace fossil tracks) that they possibly arose a few hundred million years earlier.

    Methinks you are confusing metazoans for multicellular.

    As Paul pointed out colonies of the same unicellular organisms are multicellular.

    Thorton:
    The oldest known unicellular life dates back to 3.5 billion years.

    So what?

    Did you know the fossil evidence is of stromatolites- which is formed by a colony, ie multicellular?

    IOW once again diaper boy demonstrates its ignorance...

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  52. diaper boy:
    The oldest known multicellular animals date to the early Ediacaran period some 610-630 million years ago.

    The topic isn't about multicellular animals- BTW scientists call them metazoans.

    IOW once again you prove that you are a clueless dolt.

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  53. JoeTard said...

    Thorton:
    The oldest known multicellular animals date to the early Ediacaran period some 610-630 million years ago.

    The topic isn't about multicellular animals


    LOL! That's why the title of this thread is

    "Brown Algae and The Serendipity of Multicellularity"

    JoeTard: still unable to read for comprehension.

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  54. diaper boy,

    As Paul has said multicellularity just means multiple cells- as in a colony/ Volvox.

    It does not mean metazoans.

    IOW thank you for proving that you are a retarded freak.

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  55. BTW brown algae is not a multicelular animal you ignorant joke...

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  56. Paul:
    "Multicellularity refers to an organism comprising multiple cells, not multiple cell types, although this is of course common."

    IOW diaper boy needs a diaper change...

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  57. Joe G says:"IOW my position is that multicellularity- as in forming colonies and even the Volvox is that nothing evolved- that the organisms had the ability to do so from the start."

    I think you are overstating the status of colony-forming behaviour. My point in discussing Volvox and Porifera is very much that these are proto-multicellular arrangements. Metazoans have a much more complex type of multicellularity whereby cells are specialised and cannot exist independently for even short periods. They also have more complex intercellular communication. Volvox and sponges, with 2 or 3 cell types are much more like aggregations of cells that benefit from colony forming but have greater degrees of independence - perhaps loosely analogous to the interdependence between different species in lichens. Prior to this in earth's timeline, colonies of otherwise unicellular life are known to have existed, but it is worth stressing that an homogeneous aggregration of one cell type is not multicellularity on the same level as humans, nematodes, sponges or trees.

    As Thornton quite correctly points out the complex multicellularity of metazoans did not arise until the end of the Precambrian era, indicating very much that something did evolve.

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  58. "IOW my position is that multicellularity- as in forming colonies and even the Volvox is that nothing evolved- that the organisms had the ability to do so from the start."

    Paul:
    I think you are overstating the status of colony-forming behaviour.

    No, I am just making a point.

    Paul:
    My point in discussing Volvox and Porifera is very much that these are proto-multicellular arrangements.

    Not proto- they are multicellular.

    Paul:
    "Metazoans have a much more complex type of multicellularity whereby cells are specialised and cannot exist independently for even short periods."

    Yes I know.

    Paul:
    "but it is worth stressing that an homogeneous aggregration of one cell type is not multicellularity on the same level as humans, nematodes, sponges or trees."

    Yes I know.

    Paul:
    As Thornton quite correctly points out the complex multicellularity of metazoans did not arise until the end of the Precambrian era, indicating very much that something did evolve.

    That is false.

    We don't know when metazoans arose.

    The fossil record isn't complete and absence of evidence is not evidence of absence.

    And there isn't any evidence that metazoans can evolve from multicellular colonies.

    IOW as far as anyone knows the Earth was terraformed by some alien race in need of a new home.

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  59. JoeG says:"Not proto- they are multicellular.

    They have a less complex form of multicellularity in the ways I have described now several times, and to which you've responded that "you know". Defining them simply as multicellular and ignoring the details of their difference makes no sense.

    "We don't know when metazoans arose."

    Fine. Let us say then that there is no evidence of metazoans existing prior to the Ediacaran period, despite numerous records of single celled organisms that predate the Ediacaran by billions of years. It hardly changes the substance of the argument.

    "The fossil record isn't complete and absence of evidence is not evidence of absence.

    Indeed the fossil record is incomplete. But what we have is the absence of evidence for billions of years followed by gratuitous volumes of evidence in the past 600 million years. To suggest nothing can be read from this is greatly disingenuous.

    "And there isn't any evidence that metazoans can evolve from multicellular colonies."

    I haven't a clue what you would consider evidence. Intermediate forms show the possibility exists.

    "IOW as far as anyone knows the Earth was terraformed by some alien race in need of a new home."

    Your aliens must be very patient types.

    Personally I prefer theories that haven't been plucked, devoid of evidence, from the air.

    IOW, I think we're done here.

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  60. Paul,

    What is the evidence that a multicellular colony- aggregates of the cell- can evolve into a metazoan?

    How can we even test such a premise?

    Can we take slime-mold and tinker with it until a metazoan starts to develop?

    As for your timeframe- how do you know it's accurate?

    We are finding today that catastrophes can cause geological formations that we once thought took millions of years to create can happen in days or weeks.

    So in order to put a time line on the fossil record we have to know how it was formed.

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