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posted by Fnord666 on Tuesday May 29 2018, @04:35AM   Printer-friendly
from the like-a-bad-penny dept.

Submitted via IRC for guy_

Plants, like all living things, need nitrogen to build amino acids and other essential biomolecules. Although nitrogen is the most abundant element in air, the molecular form of nitrogen found there is largely unreactive. To become useful to plants, that nitrogen must first be "fixed," or busted out of its molecular form and linked with hydrogen to make ammonia. The plants can then get at it by catalyzing reactions with ammonia.

But plants can't fix nitrogen. Bacteria can.

Some legumes and a few other plants have a symbiotic relationship with certain bacterial species. The plants build specialized structures on their roots called nodules to house and feed the bacteria, which in turn fix nitrogen for the plants and assure them a steady supply of ammonia. Only 10 families of plants have the ability to do this, and even within these families, most genera opt out. Ever since the symbiosis was discovered in 1888, plant geneticists have wondered: why? If you could ensure a steady supply of nitrogen for use, why wouldn't you?

A global consortium of geneticists sequenced and compared the genomes of 37 plants—some symbiotic, some not; some that build nodules, some not; some agriculturally relevant, some not—to try to find out what was going on. The group's genetic analysis of the conundrum was reported in Science.

Source: https://arstechnica.com/science/2018/05/plants-repeatedly-got-rid-of-their-ability-to-obtain-their-own-nitrogen/


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  • (Score: 3, Insightful) by meustrus on Tuesday May 29 2018, @04:11PM (5 children)

    by meustrus (4961) on Tuesday May 29 2018, @04:11PM (#685694)

    I'd like to support your pedantry, but my eyes nearly rolled into the back of my skull trying to read your corrections. The same thing happens trying to describe how well an organism is adapted to a particular purpose without saying they were "designed" or that they "evolved" for that purpose (neither of which is entirely accurate and both of which are going to unnecessarily turn away part of the audience).

    We need better easily understandable language to describe how the plants became adapted to fix nitrogen, stop fixing nitrogen, or any other trait. Preferably, this language would accurately describe adaptation without asserting how it happened.

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  • (Score: 3, Informative) by HiThere on Tuesday May 29 2018, @06:32PM (4 children)

    by HiThere (866) Subscriber Badge on Tuesday May 29 2018, @06:32PM (#685783) Journal

    Unfortunately, the correct language is mathematical. It would be as friendly to most people as a block of assembler code to an unknown CPU. Even experts have trouble following the feedback loops involved. And even Haldane got things wrong because of that.

    People tend to think in terms of causal agents. Thinking any other way is more difficult, and leads to more mistakes, even though that's often only approximately correct.

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    • (Score: 3, Insightful) by meustrus on Wednesday May 30 2018, @04:53PM (3 children)

      by meustrus (4961) on Wednesday May 30 2018, @04:53PM (#686341)

      People tend to think in terms of causal agents. Thinking any other way is more difficult, and leads to more mistakes, even though that's often only approximately correct.

      Does that mean that for some definition of "god", talking about adapted traits as "god's design" would actually be the best balance between correctness and effective communicability? Such a god would be based on the whole of the Earth's ecosystem, which is closer to Gaia than Yhwh.

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      • (Score: 3, Insightful) by HiThere on Wednesday May 30 2018, @06:19PM (2 children)

        by HiThere (866) Subscriber Badge on Wednesday May 30 2018, @06:19PM (#686394) Journal

        No. But it does mean that talking about evolution as design is the easiest way to think about it. You don't need to specify the designer. I suppose you could go all Deist, but that implies a degree of predeterminism that isn't proven correct. (It's one possible interpretation of quantum mechanics, but no more certain than any of the other valid ones.)

        In fact, in a sense talking about it as design is correct, but explaining that sense takes a long time, and a lot of closely reasoned argument. And it depends on a particular definition of what it means for something to be designed which allows conscious intent to be absent. So you could say that the industrial pollution in Scotland designed the domination of dark winged moths over light winged moths. This is clearly an unusual meaning of design, so I started off this paragraph with "in a sense".

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        • (Score: 3, Insightful) by meustrus on Wednesday May 30 2018, @07:33PM (1 child)

          by meustrus (4961) on Wednesday May 30 2018, @07:33PM (#686434)

          it depends on a particular definition of what it means for something to be designed which allows conscious intent to be absent.

          I absolutely agree. The #1 problem with so-called "intelligent design", in my opinion, is the "intelligent" part. It implies intent where often there is none, like in your moth example. That further implies that we can understand the outcome by assigning human intelligence and motivation to the designer, which isn't even true if the designer is God. But worst of all, it implies that the actual result is the most correct outcome, with anything else being an unnatural abomination.

          Do you have any ideas for how to easily talk about adaptation as "design" while avoiding these problematic implications?

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          • (Score: 3, Informative) by HiThere on Thursday May 31 2018, @06:26AM

            by HiThere (866) Subscriber Badge on Thursday May 31 2018, @06:26AM (#686624) Journal

            The only way I can think of that "sort of" works, if you don't want to get verbose about what you mean be design, is the Deist approach. There is an interpretation of quantum mechanics that is consistent with that, but it sure isn't congenial to my thought processes. But when I think about evolution in words, "designed" automatically pops up. Dawkins created the word "designoid" to use in that circumstance, but I can't slip it into my thought processes, even though they (the thoughts) can be translated back into evolutionarily acceptable arguments. (Well, not really, because I don't really have the math, and I doubt that anyone can actually think that way, but close, close.)

            Unfortunately, evolution is "best expressed" as a multiplayer game with a very large number of players, partially hidden information, and where the different players get different payoffs in the same situation. Even simplified this math is formidable...and well beyond me. So, for example, you can't really talk about the evolution of an eye as separated from the rest of the circumstances. Even specialists in evolution do, though, because nobody can handle the real math. And there's probably a bit a chaos in there to, so that even slightly different initial conditions would yield a different result, though there are certainly basins of attraction. And that leaves out various truly random occurrences such a mutations, or giant meteor impacts.

            So everyone oversimplifies evolution, because there isn't any other way to even try to handle it. When I say "an eye is designed to see with" I'm talking about the same designer that "it's raining" uses as the actor. It's not valid logically, but it's valid linguistically.

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