AuldSoul:
It is a challenge to Dawkinsian Neo-Darwinism which suggests that each organism is engaged in a separate, segregated fight to survive.
Ah, so it's a challenge to a belief that nobody actually holds. No big deal, then.
Endosymbiosis --- A challenge to Dawkins' Universal Darwinism
by hamilcarr 46 Replies latest jw friends
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funkyderek
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AuldSoul
Ah, so it's a challenge to a belief that nobody actually holds. No big deal, then.
Miniscule and exponentially manifest organismic response to environmental pressures is only predicted in a system where the organism strives to survive.
"Natural selection", as explained by Dawkins and as initially suggested by Darwin to explain the obvious commonality he saw, requires that the organism cares whether it survives. It also requires that there be an empirically demonstrable acquisition of new code (or activation of dormant code) that is beneficial to a species in order to be proved.
Margulis' theory utterly solves the problem of "new code". But this is, in my opinion, merely incidental to the true beauty of her theory and its potential to unify our comprehension of several fields of science which have been relatively bad bedfellows to date.
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BurnTheShips
Endosymbiosis either happened as a result of random mutation, or in itself represents a kind of random macro-mutation
I'd really like to see how.
When all you have is a hammer, every problem looks like a nail.
BTS
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funkyderek
AuldSoul:
Miniscule and exponentially manifest organismic response to environmental pressures is only predicted in a system where the organism strives to survive.
What? Can you rephrase that please? I can't quite make sense of it.
"Natural selection", as explained by Dawkins and as initially suggested by Darwin to explain the obvious commonality he saw, requires that the organism cares whether it survives.
No it does not. It requires merely that organisms that are better equipped to survive are more likely to survive. It can be useful to think of an organism (or gene) "caring" about its survival as long as one remembers that it is only true in a metaphorical sense.
It also requires that there be an empirically demonstrable acquisition of new code (or activation of dormant code) that is beneficial to a species in order to be proved.
Luckily there's no shortage of examples.
Margulis' theory utterly solves the problem of "new code".
It's not really a problem that needs solving. And in any case, what Margulis proposed has little bearing on most of evolution. It's quite obvious that the majority of significant mutations in the history of any species have involved point mutations, rather than the assimilation of another organism.
But this is, in my opinion, merely incidental to the true beauty of her theory and its potential to unify our comprehension of several fields of science which have been relatively bad bedfellows to date.
What is the "true beauty of her theory", to what fields of science are you referring and how can her theory help unify them?
BurnTheShips:
I'd really like to see how.
I doubt it but let's give it a go anyway. For two organisms to combine either there was a point mutation in one or both of them that allowed this novel state of affairs, or there was no such change, just a bit of environmental serendipity that brought the two together. In either case, the offspring would be significantly different genetically from its parents. Such a sudden and profound genetic change could be thought of as a macro-mutation.
Alternatively, of course, it's possible to think of each organism as part of the environment of the other, as each continues to pass its genes along separately. Over time mutations in both organisms increase the advantage that the symbiosis initially gave them.
Whichever view you take it quickly becomes obvious that such a situation presents no problem for Darwinism, universal Darwinism, neo-Darwinism, Dawkinsian neo-Darwinism or any other view that is actually held by mainstream biologists.
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BurnTheShips
Playing fast and loose with scientific terms FD? Mutation has a specific meaning in this context and it is not what happens in a symbiotic merge. FD, FD, FD. The symbiosis is a fundamentally different thing from the self contained mutation.You could think of it as a mutation, just as I can think of last night's dinner mutating and evolving into this morning's smelly turd (which would have a lot in common with your post above)--but it's not the same thing is it? Did my beef and bean burrito with extra hot salsa and a side of guacamole washed down with a Corona mutate or evolve (in a Darwinian sense) into the mephitic juggernaut that cleared an entire employee restroom? Did the excessive backsplashing and brown streaks on the back of the bowl represent a new adaptive cusp to be admired by all existing forms if Mexican cuisine? Was the noisy expulsion a new mating call, or a cri du coeur heralding a new level of existence? I don't think so, and neither did the chimichangas that I turned down either; and the same is true here. The burrito and myself entered into a special relationship, which resulted in a call to the janitorial staff. All change was a result of the relationship and not mutation.
Whichever view you take it quickly becomes obvious that such a situation presents no problem for Darwinism, universal Darwinism, neo-Darwinism, Dawkinsian neo-Darwinism or any other view that is actually held by mainstream biologists.
Madame Margulis seems to think otherwise.
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funkyderek
BurnTheShips:
Playing fast and loose with scientific terms FD?
A little.
Mutation has a specific meaning in this context and it is not what happens in a symbiotic merge.
Agreed. Which is why I said it's a "kind of macro-mutation". It has some of the functional effects of a large mutation, but that really only holds if we think of the symbiont as an individual organism descended from one or other of the original cells. On reflection it is really only adaptation to a specific environment. In this case the environment is another organism, or more correctly, each organism is part of the environment of the other. Of course, this is only difficult because we have a tendency to think on the level of living organisms, forgetting that the idea is largely an artificial construct. If we look on the genetic level, what we see are genes mutating and responding to changes in their environment in such a way that those best suited to surviving are those that survive.
Madame Margulis seems to think otherwise.
Good for her.
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hamilcarr
Endosymbiosis either happened as a result of random mutation, or in itself represents a kind of random macro-mutation
The neo-Darwinists say that variation originates from random mutation, defining mutation as any genetic change. By randomness they mean that characters appear randomly in offspring with respect to selection: if an animal needs a tail, it doesn't develop this tail because it needs it; rather, the animal randomly develops all sorts of changes and those with tails survive to produce more offspring. H.J. Muller, in the 1920s, discovered that not only do X rays increase the fruit-fly mutation rate, but even if fruit flies are isolated completely from X rays, solar radiation, and other environmental perturbation, a spontaneous mutation rate can be measured. Inherited variants do appear spontaneously; they have nothing to do with whether or not they're good for the organism in which they appear. Mutation was then touted as the source of variation- -that upon which natural selection acted — and the neo-Darwinian theory was declared complete. The science remaining required filling in the gaps in a "theory" with very few holes.
From many experiments, it is known that if mutagens like X rays or certain chemicals are presented to fruit flies, sick and dead flies result. No new species of fly appears — that is the real rub. Everyone agrees that such mutagens produce inherited variation. Everyone agrees that natural selection acts on this variation. The question is, From where comes the useful variation upon which selection acts? This problem has not yet been solved. But I claim that most significant inherited variation comes from mergers — from what the Russians, especially Konstantin S. Mereschkovsky, called symbiogenesis and the American Ivan Emanuel Wallin called symbionticism. Wallin meant by the term the incorporation of microbial genetic systems into progenitors of animal or plant cells. The new genetic system — a merger between microbe and animal cell or microbe and plant cell — is really different from the ancestral cell that lacks the microbe. Analogous to improvements in computer technology, instead of starting from scratch to make all new modules again, the symbiosis idea is an interfacing of preexisting modules. Mergers result in the emergence of new and more complex beings. I doubt new species form just from random mutation.
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funkyderek
hamilcarr:
But I claim that most significant inherited variation comes from mergers [...]I doubt new species form just from random mutation.
While mergers of this type obviously have the potential to radically alter the sorts of bodies future copies of certain genes will find themselves in, it's important to note that the merger itself results in no new information, it's just a new environment for two already extant genomes. The new information comes as random mutations that benefit the new merged organism are selected. Also, it doesn't require much thought to realise that mergers like this can only take place at the level of single-celled or at least very small and simple organisms. Nobody could seriously be proposing that the differences between humans and apes (for example) are the result of such a merger.
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BurnTheShips
While mergers of this type obviously have the potential to radically alter the sorts of bodies future copies of certain genes will find themselves in, it's important to note that the merger itself results in no new information, it's just a new environment for two already extant genomes. The new information comes as random mutations that benefit the new merged organism are selected. Also, it doesn't require much thought to realise that mergers like this can only take place at the level of single-celled or at least very small and simple organisms. Nobody could seriously be proposing that the differences between humans and apes (for example) are the result of such a merger.
Hamlet is just a merger of many already extant English words, no new information comes from already extant words.
Right?
BTS
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hamilcarr
Nobody could seriously be proposing that the differences between humans and apes (for example) are the result of such a merger.
According to a later theory by Margulis, symbiotic relations between organisms of different kingdoms (or domains, for instance between prokaryots and eukaryots) are the driving force behind evolution. Results from the Human Genome Project have recently lend support to this hypothesis because it was shown that significant portions of the human genome are either of bacterial or viral in origin.