I just finished reading a brief review of a paper in Nature 467, 929-934 (21 Oct. 2010) Nick Lane and William Martin.
This is a quote from the paper.
" All complex life is composed of eukaryotic (nucleated) cells. The eukaryotic cell arose from prokaryotes just once in four billion years, and otherwise prokaryotes show no tendency to evolve greater complexity. Why not? Prokaryotic genome size is constrained by bioenergetics. The endosymbiosis that gave rise to mitochondria restructured the distribution of DNA in relation to bioenergetic membranes, permitting a remarkable 200,000-fold expansion in the number of genes expressed. This vast leap in genomic capacity was strictly dependent on mitochondrial power, and prerequisite to eukaryote complexity: the key innovation en route to multicellular life" Later Lane and Martin state:
"The transition to complex life on Earth was a unique event that hinged on a bioenergetic jump afforded by spatially combinatorial relations between two cells and two genomes (endosymbiosis), rather than natural selection acting on mutations accumulated gradually among physically isolated prokarykotic individuals. Given the energetic nature of these arguments, the same is likely to be true of any complex life elsewhere"
My question is: Does this mean the authors are saying that natural selection was not the cause of the evolution of the eukaryotic cell from the prokaryotic cell?
And if true what effect does that have for The Darwinian and neo-Darwinian theory of gradual descent by random mutution and natural selection?
Thanks Rahvim and Catholic Scientist. The reviewer of the paper at www.selectsmart.com one Pate De Parodic stated after reviewing the paper:
"Basicially the problem is that a primitive bacteria cannot evolve mitochondria by 'jugglilng its genes'. It would require that one of these primitive bacteria absorb and adapt by swallowing or absorbing an entirely new cell. On earth this has never been observed happening with prokaryotic cells. However eukaryotic cells indeed have been observed to do this. For a prokaryotic cell to transform to a eukaryotic cell it would have to do things that seem to only happen in eukaroytic cells"
[gs]Did you read about the Endosymbiotic Theory that I linked to?[/gs]
I did but my understanding of that article is that the theory has not been fully accepted. Lane and Martin state that a prokaryote has evolved once in four billion years into a eukaryote. So I am still quite confused. Thanks for your help
"The transition to complex life on Earth was a unique event that hinged on a bioenergetic jump afforded by spatially combinatorial relations between two cells and two genomes (endosymbiosis), rather than natural selection acting on mutations accumulated gradually among physically isolated prokarykotic individuals.
This is the part of the quote from Lane & Martin that I have a problem understanding.
I understand this to mean that the TRANSITION TO COMPLEX LIFE was a unique event that did not rely on natural selection. Was the transition from prokaroyte to eukaroyte an example of macro evolution?
I don't like the expression "rely on natural selection." However, natural selection would be as much involved here as with anything else.
Nick Lane says in his paper "The transition to COMPLEX LIFE(My emphasis) on Earth was a UNIQUE event that hinged on a bioenergetic jump afforded by spatially combinatorial relations between two cells and two genomes (endosymbiosis) rather than natural slection actilng on mutations..."
I think he is pretty clear that natural selection was not involved in the transition to complex life. That this was jump and not a gradual transition. I interpret this to mean that there was a vast increase in genes during the transition and this increase did not evolve by natural selection. Therefore it could be assumed, if Lane is correct, that this was a macroevolutionary event w/o natual selection. By the way Lane seems to be very well qualified and is an evolutionist. www.nick-lane.net
As to whether they are right about the mutations, it depends on how you look at things. If you conceive of the pre-endosymbiosis eukaryote and the mitochondria as being and remaining two organisms, then you have a fairly normal case of the evolution of symbiosis. If you look at them as becoming one organism, the post-endosymbiosis eukaryote, then the eukaryote received a whole lot of genes suddenly by an unusual form of lateral gene transfer.
Edited I read it to mean that there was a unique jump from prokaroyte to eukaryote, ie to complex life w/o natural selection. That seems to me to be a macroevolutionary event. Lane seems to be very well qualifed www.nick-lane.net
If I may, I think what is being said here is not that natural selection was not involved, but that random mutation was the force playing a reduced role. The leap to eukaryotic life was not the kind of change that took place bit-by-bit, under random mutation in the normal sense. It was much more sudden, but that doesn't mean that natural selection would not have come into play as eukaryotes emerged.
Lane is pretty clear that natural selection was not involved. He says it was "a jump" and a unique event. I take that to mean it was not a normal evolutionary event as would be expected per Darwinan or neo-Darwinan theory.
Edited by shadow71, : insert "as would be expected " in 3rd sentence.
this is in reply to granny magda 483 & 488, bluejay 491 and nwr 486
Yes and I think that it's fair to say that it was a very unusual event. I'm not sure why you seem to think that NS could not have acted upon the earliest eukaryotes though. Remember, NS is what selects from amongst varieties that already exist. It does not create variety itself, it only acts as a filter. Just because the normal process of random mutation would have had a reduced role in the change to endosymbiosis does not mean that NS would not have taken place. I do not believe that Lane intended to imply this.
I am not saying that NS was not involved after the jump from prokaryote to eukaroyte, or that NS & mutation were not involved in prokaryote prior to the jump. But the jump per Lane & Martin was a "unique event", that did not rely on NS. Not sure if I am clear, but I interpret this to mean that the jump from ProK to EuroK was a moment of Macro evolution.
Some papers I have been reading are leaning toward the hypothesis that Macro evolution, or the transition to complex entities, does not rely on NS and mutation, but on genetic information engineering processes and are almost instant in nature compared to the gradualness of micro evolution.
This seems to be in concert with Lane & Martin. Remember I am not a biologist, and you all should know that I am a practicing Roman Catholic who believes as the church does that evolution is a continuing process, but was not initiated by a Natural act. In other words, nature is performing it's, shall we say programmed, work.
Then how does this "jump" differ from the evolution of any other form of symbiosis? And in what sense is it a "jump"?
What exactly are you visualizing as happening here?
Lane and Martin state "The transition to complex life on Earth was a unique event..."
I interpret that to mean a jump from simple prokaroyte to a complex eukaroyte. This is not a gradual mutation, natural selection process as in microevolution. It is a jump from one species to another, a macroevolution event.
Saying that it was unique doesn't mean that it was a saltation.
And I don't see how a saltation would have worked. Surely they can't have "jumped" in a single step from no symbiosis to obligate endosymbiosis. How do you envisage that happening?
I am not a biologists, but can only rely on the papers I read by the experts in the field. Carl Woese's work indicates that there may have been a saltation whereas the proK's, EuroK's and Archaea arose from a change in cell organizations early on that gradually led to the evolution theory now accepted by Darwinians & neo-Darwinains. This seems in line w/ Lane & Martin's paper.
If true this slatation or saltations may have been the precusor of micro evolution.
"Evidence today strongly suggests that a highly developed translation system was a necessary condition for the emergence of cells, as we know them. In the universal phylogenetic tree (UPT) format, this maturation of the translation system seems to be represented by the tree's basal branchings, where first the bacterial and then the archaeal and eukaryotic lineages appear individually to emerge. What lies beneath the "root" locus, the evolution leading up to it, cannot be captured in familiar tree representation. It would seem to be some distributed universal ancestral state from which the (three) primary organismal lineages materialized via one or a brief series of major evolutinary saltations in which the state of the evolving cellular organization and the accompanying evolutionary dynamic underwent dramatic change. The aboriginal evolutionary dynamic may have been "Lamarckian" in the sense that it seems likely to have involved massive pervasive horizontal transfer of genes (HGT), innovation sharing. The kind and frequency of the HGT envisioned would make evolution early on effectively communal. This communal evolutinary dynamic comes to an end relatively suddenly and transroms largely into the familar genealogical dynamic when the evolving organisms in the community reach a stage of 'critical complexity,' wherein their organizations change significantly and rapidly, becoming more refined and individualized, more 'self-composed'. These we call Darwinian transitions..."
That seems to me to be in line with what Lane and Martin are saying.
Sorry my cite does not work. You may google "molecular signatures of ribosomal evolution Elijah Roberts, ... Carl R. Worse
From your later posts, its seems like you think that L&M are saying that the prokaryote evolved one time in one single organism. Yeah?
This is the source of your confusion, me thinks.
I belive that is what they are saying. A unique event that happened only once in four billion years. If you read the post in reply to Dr. Adequate, Carl Woese seems to be saying the same thing. It appears there was a saltation, a unique jump, from simple life to complex life that the scientists cannot explain. A translation that is not accountable by Darwin's or neo-Darwinian theory. I believe this supports my theory of planned transition from original life to evolution and gradual changes in life.
"The origin of the translation system is, arguably, the central and hardest problem in the study of the origin of life, and one of the hardest in all evolutionary biology. The problem has a clear catch-22 aspect: high translation fidelity hardly can be achieved without a complex, highly evolved set of RNAs and proteins but an elaborate protein machinery could not evolve without an accurate translation system.,,
"Here we combine the results of comparative genomics of translation system components, data on interaction of amino acids with their cognate codons and anticodons, and data on catalytic activities of ribozymes to develop conceptual models for the orgin of the translation system and genetic code"
Here is the conclusion: "The scenarios for the origin of the translation system and the genetic code outlined here are both sketchy and highly speculative. Why, then bother building such conceptual qualitative models at all? The justification for this kind of theorizing can be succinctly put in the short phrase: we have to get from there to here..." http://www.biology-direct.com/content/2/1/14
There are just some things science will not be able to solve. The intricate initial cells to what we have today, I accept came from some form of evolution. However I do not see how science can find the beginning of a naturally cause life. Just as the "Big Bang" angered many scientists, especially those of athestic beliefs, so the translation system cannot be solved w/o a Planned beginning.
Can I prove this no. But one at some point must logically look at all the circumstantial evidence and form an opinion. My opinion and belief is that God created life. How and in what manner I don't know. As for the "God of the Gaps" argument. I am not saying God fills in the gaps, He created life in some form and the rest is evolving.
If you want to advance an Intelligent Design hypothesis, what you need is evidence that clearly points toward the correctness of your hypothesis, not evidence that just fails to directly contradict it.
See my post 588 in answer to jar.
I am not advancing an intelligent design hypothesis, I am advancing a God created life hyothesis, that I know I cannot prove. But as Wolf et. al state, we can't prove the orgin of life but we have to get from here to there.
I believe Science & theology can co-exist, but as long as science insists that it will always find all the answers there is a problem.
I am of the opinion that science must say, we may never know the answer to this issue.
In order to commit the God-of-the-Gaps fallacy, it is first necessary to find some gaps. What we have here are transitions that scientists say are explicable by endosymbiosis and HGT respectively. You have quoted them doing so.
I do not argue God of the Gaps. I argue God created it and it is evolving.