4 ms·

I don't get the premise of the article. A tree is just a growth shape of a plant (plants are quite flexible regarding growth shapes, and often adapt to the envi

by samus 5y ago

I don't get the premise of the article. A tree is just a growth shape of a plant (plants are quite flexible regarding growth shapes, and often adapt to the environment), and a category that our minds place a plant species into. And its clearly an ancient ability common to all vascular plants to develop woody tissues. So why would we expect the tendency of a plant to become a tree to depend on its position in the phylogenetic tree? (the authors had me there for a moment. I thought they wanted to show that the phylogenetic tree is not really a tree!)

bejelentkezni 5y ago
I was under the impression that what made a tree was its woodenness so I was probably more of the target audience, and was impressed by the article.
- da39a3ee 5y ago
  You’re right that is what makes a tree. But don’t you feel that it’s obvious that different lineages of plants could acquire, and lose, woodenness independently of each other? And therefore 100% unsurprising that “tree” is not a monophyletic group.
  - asimpletune 5y ago
    After reading this article yes, but obvious? No at all.
  - williamdclt 5y ago
    Definitely not obvious. I have no idea how complex "woodiness" is, evolutionarily. It's like if you asked me "don’t you feel that it’s obvious that different lineages of animals could acquire, and lose, feathers independently of each other": probability is certainly non-zero but is it negligible or is it actually likely? No idea, I'm not an evolutionary biologist, and would read an article about it with interest
  - yxhuvud 5y ago
    It is obvious that it can happen, but it is not obvious how common it seems to be.
throwanem 5y ago
Intuition and vernacular make poor guides to the formal lexicon of taxonomy, as I learned over the course of trying to answer the question "okay, so what kind of wasp am I looking at right now, anyway?" Two years, a couple shelf-feet of research material, and a great deal of dedicated study later - "dedicated" here meaning for example that I taught myself how to bind books because they're better for annotation and reference than PDFs - I find myself more or less able to give a fairly confident answer to that question in about two-thirds of cases, and even at that I'm often not very sure. And that's all just been to develop an experienced birder's sense of where a given animal fits into the broader picture! It'd be a lot more complicated if I were more than just a casual amateur. Phylogenetically, it's likewise reasonable to say that there's no such thing as a wasp, as the category is paraphyletic in "all of Apocrita that isn't ants and bees". This doesn't render "wasp" meaningless in its vernacular sense, of course - I may know I just saw a female Auplopus architectus metallicus [1], but if you ask about her, I'll spare you the detail and just say she's a spider wasp whose babies are lucky to have a mom who's busy seeing they'll grow up big and strong like her. The point of the article isn't to discuss the vernacular, and the point of "there's no such thing as a tree" is to make a startlingly counterintuitive assertion that draws the reader into a detailed discussion of how genomic taxonomy works. Such statements constitute a fairly common rhetorical technique - one worth knowing about, so as not perhaps again to miss the forest for a single tree. [1] https://aaron-m.com/2021/01/23/auplopus-architectus-metallicus https://aaron-m.com/2021/01/23/auplopus-architectus-metallic...
thaumasiotes 5y ago
> I thought they wanted to show that the phylogenetic tree is not really a tree! Well, it isn't. That wouldn't be news. A node in the phylogenetic tree can easily have multiple parents; it's a DAG, not a tree.
zuminator 5y ago
In addition to the sibling comments, I'd point out that the article is sort of an extended riff on the phrase, "There is no such thing as a fish," which was a sloppy QI paraphrase [0][1] of a principle elucidated by the 20th century paleontologist Stephen Jay Gould, and later became the title of QI's well-known podcast [2]. And of course, fish do exist, just not in the simplistic way that many of us were taught as children, that they are one of five genetically discrete, self-contained, non-overlapping taxonomic classes: Fish, Amphibians, Reptiles, Birds and Mammals. The author is arguing that if you are going to say that about fish, you can say it about trees, fruit, and plenty of other things. That may be true, but unlike with fish, I don't ever recall being given the impression that trees and fruit were genetically discrete self-contained scientific categories. Fruit just seemed like something that some plants have, without any sense that fruity plants were necessarily more closely related than non-fruity plants. I mean, "biped" is also a category but nobody ever claimed that birds and humans are genetically discrete from the other four, six, eight, etc. legged animals. Still, it's a fun and interesting conversation, even though the author may have been forcing the fish analogy a bit. [0] QI ("Quite Interesting") is a long-running British trivia/humor related game show [1] https://www.youtube.com/watch?v=uhwcEvMJz1Y https://www.youtube.com/watch?v=uhwcEvMJz1Y [2] https://www.nosuchthingasafish.com/ https://www.nosuchthingasafish.com/
- rzzzt 5y ago
  Chairs are also brought up in philosophical debacles: http://steve-patterson.com/no-chairs-do-not-exist/ http://steve-patterson.com/no-chairs-do-not-exist/ The point seems to be close to what you describe, but not entirely: "chair" is a human-made label, assigned to physical objects in the real world, but it's too abstract. Lots of objects resembling a chair or named "chair" exist, each with their own peculiarities, features, identity, but that's just humans going around, marking stuff with an invisible label maker.
- NoGravitas 5y ago
  In a similar way, there's no such thing as a reptile. An alligator is more closely related to a sparrow than it is to a monitor lizard.
da39a3ee 5y ago
Precisely. I think this has been on HN before, or if not then another “Wow you’re gonna be surprised by this — trees aren’t monophyletic!” article. Given all the surprising examples of convergent evolution, and given human tendencies to give vernacular names to paraphyletic groups, and given that it’s obviously easy for plant lineages to increase or decrease the woodiness of their stems, it is baffling that anyone would think it surprising that “trees” aren’t monophyletic.
- camtarn 5y ago
  'Anyone'? Really? I think you massively overestimate how much general knowledge about biology people have. For a lot (I would reckon most, but obviously I have no evidence of that) of people, terms like 'paraphyletic' are literally not in their vocabulary.
  - da39a3ee 5y ago
    Yeah, no, fair enough. I didn't mean that people would express it in that terminology, or appreciate the distinction between paraphyly and polyphyly! What I'm trying to say is: anyone who has ever poked around in some wild vegetation (even as a kid) knows that "normal plants" vary quite a bit in their woodiness. There are little ones, and sort of stiff little ones, and then there are "shrubs". I think most people here have the nous to think at this point "wtf's a shrub?" and 'I am doubting that "shrub" is actually a real thing'. Hence, by extension, tree? They are just sort of big stiff things aren't they?
    - camtarn 5y ago
      Perhaps I'm just on the low end of botanical curiosity, but I wouldn't ever have made that leap myself. If you'd asked my younger self 'what is a shrub?' I would have said 'uh, like a small bush?'. It would never have occurred to me to pursue the thought any further: my mind interfaced well with mechanical and electrical and computational things, and not at all with living things! I'd just about struggled through introductory Biology at school but was never particularly interested in it. So - yes, if you'd asked me whether all trees had a single woody ancestor, I would probably have said yes. I'd come across the idea of convergent evolution in animals before, but at least convergently evolved animals were really obviously different. Trees were obviously all the same thing: big trunk, some branches, green bits on the end. Some of them were coniferous and some deciduous, but I would have guessed that was a far-back ancestral split. I had no idea that tree ferns even existed! Anyway, the conclusion of this very rambling story is that I started dating an horticulturist and rapidly learned an enormous number of mind-melting facts about plant biology. But I still remember knowing absolutely nothing.

by samus 5y ago

bejelentkezni 5y ago

I was under the impression that what made a tree was its woodenness so I was probably more of the target audience, and was impressed by the article.

da39a3ee 5y ago
You’re right that is what makes a tree. But don’t you feel that it’s obvious that different lineages of plants could acquire, and lose, woodenness independently of each other? And therefore 100% unsurprising that “tree” is not a monophyletic group.
- asimpletune 5y ago
  After reading this article yes, but obvious? No at all.
- williamdclt 5y ago
  Definitely not obvious. I have no idea how complex "woodiness" is, evolutionarily. It's like if you asked me "don’t you feel that it’s obvious that different lineages of animals could acquire, and lose, feathers independently of each other": probability is certainly non-zero but is it negligible or is it actually likely? No idea, I'm not an evolutionary biologist, and would read an article about it with interest
- yxhuvud 5y ago
  It is obvious that it can happen, but it is not obvious how common it seems to be.

throwanem 5y ago

Intuition and vernacular make poor guides to the formal lexicon of taxonomy, as I learned over the course of trying to answer the question "okay, so what kind of wasp am I looking at right now, anyway?" Two years, a couple shelf-feet of research material, and a great deal of dedicated study later - "dedicated" here meaning for example that I taught myself how to bind books because they're better for annotation and reference than PDFs - I find myself more or less able to give a fairly confident answer to that question in about two-thirds of cases, and even at that I'm often not very sure. And that's all just been to develop an experienced birder's sense of where a given animal fits into the broader picture! It'd be a lot more complicated if I were more than just a casual amateur. Phylogenetically, it's likewise reasonable to say that there's no such thing as a wasp, as the category is paraphyletic in "all of Apocrita that isn't ants and bees". This doesn't render "wasp" meaningless in its vernacular sense, of course - I may know I just saw a female Auplopus architectus metallicus [1], but if you ask about her, I'll spare you the detail and just say she's a spider wasp whose babies are lucky to have a mom who's busy seeing they'll grow up big and strong like her. The point of the article isn't to discuss the vernacular, and the point of "there's no such thing as a tree" is to make a startlingly counterintuitive assertion that draws the reader into a detailed discussion of how genomic taxonomy works. Such statements constitute a fairly common rhetorical technique - one worth knowing about, so as not perhaps again to miss the forest for a single tree. [1] https://aaron-m.com/2021/01/23/auplopus-architectus-metallicus https://aaron-m.com/2021/01/23/auplopus-architectus-metallic...

thaumasiotes 5y ago

> I thought they wanted to show that the phylogenetic tree is not really a tree! Well, it isn't. That wouldn't be news. A node in the phylogenetic tree can easily have multiple parents; it's a DAG, not a tree.

zuminator 5y ago

In addition to the sibling comments, I'd point out that the article is sort of an extended riff on the phrase, "There is no such thing as a fish," which was a sloppy QI paraphrase [0][1] of a principle elucidated by the 20th century paleontologist Stephen Jay Gould, and later became the title of QI's well-known podcast [2]. And of course, fish do exist, just not in the simplistic way that many of us were taught as children, that they are one of five genetically discrete, self-contained, non-overlapping taxonomic classes: Fish, Amphibians, Reptiles, Birds and Mammals. The author is arguing that if you are going to say that about fish, you can say it about trees, fruit, and plenty of other things. That may be true, but unlike with fish, I don't ever recall being given the impression that trees and fruit were genetically discrete self-contained scientific categories. Fruit just seemed like something that some plants have, without any sense that fruity plants were necessarily more closely related than non-fruity plants. I mean, "biped" is also a category but nobody ever claimed that birds and humans are genetically discrete from the other four, six, eight, etc. legged animals. Still, it's a fun and interesting conversation, even though the author may have been forcing the fish analogy a bit. [0] QI ("Quite Interesting") is a long-running British trivia/humor related game show [1] https://www.youtube.com/watch?v=uhwcEvMJz1Y https://www.youtube.com/watch?v=uhwcEvMJz1Y [2] https://www.nosuchthingasafish.com/ https://www.nosuchthingasafish.com/

rzzzt 5y ago
Chairs are also brought up in philosophical debacles: http://steve-patterson.com/no-chairs-do-not-exist/ http://steve-patterson.com/no-chairs-do-not-exist/ The point seems to be close to what you describe, but not entirely: "chair" is a human-made label, assigned to physical objects in the real world, but it's too abstract. Lots of objects resembling a chair or named "chair" exist, each with their own peculiarities, features, identity, but that's just humans going around, marking stuff with an invisible label maker.
NoGravitas 5y ago
In a similar way, there's no such thing as a reptile. An alligator is more closely related to a sparrow than it is to a monitor lizard.

da39a3ee 5y ago

Precisely. I think this has been on HN before, or if not then another “Wow you’re gonna be surprised by this — trees aren’t monophyletic!” article. Given all the surprising examples of convergent evolution, and given human tendencies to give vernacular names to paraphyletic groups, and given that it’s obviously easy for plant lineages to increase or decrease the woodiness of their stems, it is baffling that anyone would think it surprising that “trees” aren’t monophyletic.

camtarn 5y ago
'Anyone'? Really? I think you massively overestimate how much general knowledge about biology people have. For a lot (I would reckon most, but obviously I have no evidence of that) of people, terms like 'paraphyletic' are literally not in their vocabulary.
- da39a3ee 5y ago
  Yeah, no, fair enough. I didn't mean that people would express it in that terminology, or appreciate the distinction between paraphyly and polyphyly! What I'm trying to say is: anyone who has ever poked around in some wild vegetation (even as a kid) knows that "normal plants" vary quite a bit in their woodiness. There are little ones, and sort of stiff little ones, and then there are "shrubs". I think most people here have the nous to think at this point "wtf's a shrub?" and 'I am doubting that "shrub" is actually a real thing'. Hence, by extension, tree? They are just sort of big stiff things aren't they?
  - camtarn 5y ago
    Perhaps I'm just on the low end of botanical curiosity, but I wouldn't ever have made that leap myself. If you'd asked my younger self 'what is a shrub?' I would have said 'uh, like a small bush?'. It would never have occurred to me to pursue the thought any further: my mind interfaced well with mechanical and electrical and computational things, and not at all with living things! I'd just about struggled through introductory Biology at school but was never particularly interested in it. So - yes, if you'd asked me whether all trees had a single woody ancestor, I would probably have said yes. I'd come across the idea of convergent evolution in animals before, but at least convergently evolved animals were really obviously different. Trees were obviously all the same thing: big trunk, some branches, green bits on the end. Some of them were coniferous and some deciduous, but I would have guessed that was a far-back ancestral split. I had no idea that tree ferns even existed! Anyway, the conclusion of this very rambling story is that I started dating an horticulturist and rapidly learned an enormous number of mind-melting facts about plant biology. But I still remember knowing absolutely nothing.