5 ms·

This is crap. It doesn't say anything. Article tl;dr: Ignoring the inconceivably remote chance of life forming from non-life, it's very very rare for simple

by eof 16y ago

This is crap. It doesn't say anything. Article tl;dr: Ignoring the inconceivably remote chance of life forming from non-life, it's very very rare for simple life to evolve into more complicated life. Also, we just realized that cells need to get bigger to get more complex, and that somehow isn't just 'another' mutation. And then the title? There is nothing about how or why complex life only evolved once. Just that it was unlikely. Chance of life forming from non life * age of the universe * number of stars * the chance a star has an earth like planet, is far from zero. I wouldn't even bother ranting but this was number 3 on the front page.

earnubs 16y ago
Isn't the optimistic guess at Drake 2 or something (correct me if I'm wrong)? That's not /very/ far from zero, and if you consider that it's the number in the Milky Way I'd say that's pretty very much close to zero.
danteembermage 16y ago
I upvote based on content not title. Perhaps a mod can change it to "New theory suggests Mitochondria precede complexity in early life" I definitely would classify engulfing mitochondria as not just another mutation, it's an entirely different thing.
- eof 16y ago
  Then everything is an entirely different thing. The simple act of a single cell engulfing mitochondria is not the birth of a species. Even on content I would bury this if I had the button for it, it makes pretty heavy claims without any evidence and necessarily brushing aside fundamental problems with the overall conclusion. I am not bashing the scientific article that this editorial is 'about'; but the article itself, besides a tiny nugget about the necessity of mitochondria being perhaps otherwise overlooked, it is just drivel.
pygy_ 16y ago
The original article [1] is titled "The energetics of genome complexity", which is much more reasonable. It argues that the energy processing of mitochondria was necessary in order for eukaryotes to expand in complexity. The article is behind a paywall, so I can't read the details. Anecdotically, there exist anaerobic eukariot cells that live on hydrogenosomes [2]. I don't know if they were originally aerobic and lost their mitochondria, or if they evolved in parallel. There also exist sea slugs that live in symbiosis with the chloroplasts of the algae they eat [3], so this kind of symbiosis has happened more than once. 1. http://www.nature.com/nature/journal/v467/n7318/full/nature09486.html http://www.nature.com/nature/journal/v467/n7318/full/nature0... 2. http://en.wikipedia.org/wiki/Hydrogenosome http://en.wikipedia.org/wiki/Hydrogenosome 3. http://www.plantphysiol.org/cgi/content/full/123/1/29 http://www.plantphysiol.org/cgi/content/full/123/1/29
- nollidge 16y ago
  One of the perks of working for a school... I'll try to summarize as best I can: The main calculation in the Nature paper is the energy budget of a cell. They give the example of E. coli: "to raise gene number tenfold, E. coli must also increase its energy budget by close to tenfold; and therein lies the problem." The reason so much more energy is required is due to protein synthesis (DNA codes to RNA which codes proteins, if you're unfamiliar with genetics). So obviously with a larger genome, there's more proteins to synthesize, and this cannot be accomplished by simply making fewer copies of the old proteins. If anything, you need more of some of those original proteins as infrastructure support for this new Genome 2.0. So (and this is my wording) prokaryotes are at a local maximum for genome and cell size. Chucking mitochondria into the picture provides the wattage (literally) for them to reach a much greater genome and cell size, and therefore organismic complexity.
  - anigbrowl 16y ago
    I am unclear about why the acquisition of mitochondria by a cell is considered to be such an unlikely event, as I lean towards the view that given enough cells/space/time, unlikely short term possibilities become distinct probabilities eventually. Also, I can't help wondering if the reason that simple cells are not observed to absorb free mitochondria is that eukaryotic cells and the organisms they evolved into have somehow poisoned the well, or attacked newly-complex competitors so aggressively that they've suppressed the population of omnivorous simple cells. But I'm no biologist. Am I missing something obvious, or is there a particular paper explaining why this mitochondrial upgrade is considered such an unlikely event?
zeteo 16y ago
"Chance of life forming from non life * age of the universe * number of stars * the chance a star has an earth like planet, is far from zero" You have no proof for this, and things can well be the other way round. Let n = age of the universe * number of stars * the chance a star has an Earth like planet n is a number that we currently have a pretty good guess at. Let p = chance of life forming from non life on Earth-like planet within a given year. We are basically clueless as to the value of p. p may well be much less than 1/n, which would make our biosphere very special indeed.
- eof 16y ago
  I have no proof for it, but I don't need it. The burden of proof is not on me. They are making the claim that 'complex life only happened once'. Life certainly does exist so p > 0. Since our understanding (or I should say, my under standing of 'our' understanding) of n is approaching infinity, it stands to reason that p x n is > 0.
  - zeteo 16y ago
    You've made a statement that a certain quantity is far larger than zero, so you do incur a burden of proof for that statement. p * n > 0 doesn't imply p * n >> 0, not even for large values of n (and "approaching infinity" doesn't apply to constants).
    - eof 16y ago
      Sorry, 'far from zero' is really meaningless and I shouldn't have said it that way. I don't actually mean to make a positive statement about the existence of complex life elsewhere in the universe, though intuitively I think it's absurd to believe our little planet is the only one with life on it. I mean, why would we believe that other than residual religious dogma? Our understanding of n is not a constant.
      - jerf 16y ago
        "I mean, why would we believe that other than residual religious dogma?" Because when we look out into the universe, it looks like we expect it to look when it is dead, not full of life, some significant percentage of which becomes intelligent. Nothing that looks like Dyson spheres of any form (recalling that the "solid shell" is actually only a special case), nothing that looks like curated stellar evolution (very high-end stuff but a truly advanced civilization will not want to leave stars just randomly flying around a galaxy and exploding), very very little that could even conceivably be a ship traveling between the stars (which turns out with any physically-plausible propulsion mechanism to be visible from a very long ways away and would show very clear blue/red shift changes), nothing that doesn't appear entirely natural. This isn't the whole story (maybe they're hiding, maybe our idea of the top end of tech is wrong, maybe they're all virtual, maybe they escaped into another, friendlier dimension, maybe they all kill themselves, maybe the universe is soaked with simple life but this article is essentially correct and complex intelligent life really is a 10^-1000 event, etc.), but it is not true that the claim that complex life must be hard is some sort of stupid idea in light of the size of the universe. Arguably it's actually the claim best supported by the evidence at this time. People are really bad at thinking about small probabilities even on the scale of one out of a million, and it's not impossible that complex intelligent life turns out to be one out of 10^1000 or worse; we simply don't know. It is not hard to come up with calculations that plausibly set the odds of advanced life occurring even once in the universe as less than 50/50 without having to make stuff up. Our ignorance dominates our knowledge here.
jokermatt999 16y ago
The last part of your post is known as the Drake Equation (http://en.wikipedia.org/wiki/Drake_equation http://en.wikipedia.org/wiki/Drake_equation). I'm guessing you've probably heard of it, but it could be of interest to other people, so I figured I'd link it.
- Roboprog 16y ago
  Tangent: the Drake Equation seems to be the template for a class of "Google interview" questions: estimate something you can't really know, at least off the top of your head, in which you then start to identify factors, and start to guess at upper and lower bounds, to come back with a plausible answer, or at least a range. I suppose a lot of research is like that, but the Drake just happens to deal with factors that are harder to measure.

by eof 16y ago

earnubs 16y ago

Isn't the optimistic guess at Drake 2 or something (correct me if I'm wrong)? That's not /very/ far from zero, and if you consider that it's the number in the Milky Way I'd say that's pretty very much close to zero.

danteembermage 16y ago

I upvote based on content not title. Perhaps a mod can change it to "New theory suggests Mitochondria precede complexity in early life" I definitely would classify engulfing mitochondria as not just another mutation, it's an entirely different thing.

eof 16y ago
Then everything is an entirely different thing. The simple act of a single cell engulfing mitochondria is not the birth of a species. Even on content I would bury this if I had the button for it, it makes pretty heavy claims without any evidence and necessarily brushing aside fundamental problems with the overall conclusion. I am not bashing the scientific article that this editorial is 'about'; but the article itself, besides a tiny nugget about the necessity of mitochondria being perhaps otherwise overlooked, it is just drivel.

pygy_ 16y ago

The original article [1] is titled "The energetics of genome complexity", which is much more reasonable. It argues that the energy processing of mitochondria was necessary in order for eukaryotes to expand in complexity. The article is behind a paywall, so I can't read the details. Anecdotically, there exist anaerobic eukariot cells that live on hydrogenosomes [2]. I don't know if they were originally aerobic and lost their mitochondria, or if they evolved in parallel. There also exist sea slugs that live in symbiosis with the chloroplasts of the algae they eat [3], so this kind of symbiosis has happened more than once. 1. http://www.nature.com/nature/journal/v467/n7318/full/nature09486.html http://www.nature.com/nature/journal/v467/n7318/full/nature0... 2. http://en.wikipedia.org/wiki/Hydrogenosome http://en.wikipedia.org/wiki/Hydrogenosome 3. http://www.plantphysiol.org/cgi/content/full/123/1/29 http://www.plantphysiol.org/cgi/content/full/123/1/29

nollidge 16y ago
One of the perks of working for a school... I'll try to summarize as best I can: The main calculation in the Nature paper is the energy budget of a cell. They give the example of E. coli: "to raise gene number tenfold, E. coli must also increase its energy budget by close to tenfold; and therein lies the problem." The reason so much more energy is required is due to protein synthesis (DNA codes to RNA which codes proteins, if you're unfamiliar with genetics). So obviously with a larger genome, there's more proteins to synthesize, and this cannot be accomplished by simply making fewer copies of the old proteins. If anything, you need more of some of those original proteins as infrastructure support for this new Genome 2.0. So (and this is my wording) prokaryotes are at a local maximum for genome and cell size. Chucking mitochondria into the picture provides the wattage (literally) for them to reach a much greater genome and cell size, and therefore organismic complexity.
- anigbrowl 16y ago
  I am unclear about why the acquisition of mitochondria by a cell is considered to be such an unlikely event, as I lean towards the view that given enough cells/space/time, unlikely short term possibilities become distinct probabilities eventually. Also, I can't help wondering if the reason that simple cells are not observed to absorb free mitochondria is that eukaryotic cells and the organisms they evolved into have somehow poisoned the well, or attacked newly-complex competitors so aggressively that they've suppressed the population of omnivorous simple cells. But I'm no biologist. Am I missing something obvious, or is there a particular paper explaining why this mitochondrial upgrade is considered such an unlikely event?

zeteo 16y ago

"Chance of life forming from non life * age of the universe * number of stars * the chance a star has an earth like planet, is far from zero" You have no proof for this, and things can well be the other way round. Let n = age of the universe * number of stars * the chance a star has an Earth like planet n is a number that we currently have a pretty good guess at. Let p = chance of life forming from non life on Earth-like planet within a given year. We are basically clueless as to the value of p. p may well be much less than 1/n, which would make our biosphere very special indeed.

eof 16y ago
I have no proof for it, but I don't need it. The burden of proof is not on me. They are making the claim that 'complex life only happened once'. Life certainly does exist so p > 0. Since our understanding (or I should say, my under standing of 'our' understanding) of n is approaching infinity, it stands to reason that p x n is > 0.
- zeteo 16y ago
  You've made a statement that a certain quantity is far larger than zero, so you do incur a burden of proof for that statement. p * n > 0 doesn't imply p * n >> 0, not even for large values of n (and "approaching infinity" doesn't apply to constants).
  - eof 16y ago
    Sorry, 'far from zero' is really meaningless and I shouldn't have said it that way. I don't actually mean to make a positive statement about the existence of complex life elsewhere in the universe, though intuitively I think it's absurd to believe our little planet is the only one with life on it. I mean, why would we believe that other than residual religious dogma? Our understanding of n is not a constant.
    - jerf 16y ago
      "I mean, why would we believe that other than residual religious dogma?" Because when we look out into the universe, it looks like we expect it to look when it is dead, not full of life, some significant percentage of which becomes intelligent. Nothing that looks like Dyson spheres of any form (recalling that the "solid shell" is actually only a special case), nothing that looks like curated stellar evolution (very high-end stuff but a truly advanced civilization will not want to leave stars just randomly flying around a galaxy and exploding), very very little that could even conceivably be a ship traveling between the stars (which turns out with any physically-plausible propulsion mechanism to be visible from a very long ways away and would show very clear blue/red shift changes), nothing that doesn't appear entirely natural. This isn't the whole story (maybe they're hiding, maybe our idea of the top end of tech is wrong, maybe they're all virtual, maybe they escaped into another, friendlier dimension, maybe they all kill themselves, maybe the universe is soaked with simple life but this article is essentially correct and complex intelligent life really is a 10^-1000 event, etc.), but it is not true that the claim that complex life must be hard is some sort of stupid idea in light of the size of the universe. Arguably it's actually the claim best supported by the evidence at this time. People are really bad at thinking about small probabilities even on the scale of one out of a million, and it's not impossible that complex intelligent life turns out to be one out of 10^1000 or worse; we simply don't know. It is not hard to come up with calculations that plausibly set the odds of advanced life occurring even once in the universe as less than 50/50 without having to make stuff up. Our ignorance dominates our knowledge here.

jokermatt999 16y ago

The last part of your post is known as the Drake Equation (http://en.wikipedia.org/wiki/Drake_equation http://en.wikipedia.org/wiki/Drake_equation). I'm guessing you've probably heard of it, but it could be of interest to other people, so I figured I'd link it.

Roboprog 16y ago
Tangent: the Drake Equation seems to be the template for a class of "Google interview" questions: estimate something you can't really know, at least off the top of your head, in which you then start to identify factors, and start to guess at upper and lower bounds, to come back with a plausible answer, or at least a range. I suppose a lot of research is like that, but the Drake just happens to deal with factors that are harder to measure.