5 ms·

This seems to say that forests were gone, so all tree dwelling birds died out and thus all modern birds are descended from ground dwelling birds. Looking at th

by cwmma 8y ago

This seems to say that forests were gone, so all tree dwelling birds died out and thus all modern birds are descended from ground dwelling birds. Looking at the paper [1] it seems to only say 'reduced flight capacity' which makes more sense, considering we only know of 4 times flight has only evolved so this would be a big deal if birds had evolved it twice. 1. https://www.cell.com/current-biology/fulltext/S0960-9822(18)30534-7 https://www.cell.com/current-biology/fulltext/S0960-9822(18)...

robbrown451 8y ago
But this time they wouldn't have to evolve it from scratch. It's not hard to imagine a bird such as an ostrich evolving into a flight capable bird, especially if there were no existing flighted birds to compete with. They have elaborate feathered wings, so the biggest change needed is probably just to be smaller. Probably 99.9% of the DNA necessary for flight is already there, it just needs to be regulated a bit differently. This would even be true in birds like kiwis or emus, whose wings are much smaller and vestigial.
GuiA 8y ago
It would certainly be a fantastic discovery, but would it be that surprising? The amount of knowledge we can infer from the fossil record is infinitesimal compared to all that actually happened; and while going from 0 instances of an event to 1 is notable (it tells us that “it can happen”), so is 1 to 2 (it tells us that “it can happen more than once”), but is 4 to 5 that crazy?
- dekhn 8y ago
  Under the mostly accepted principle of parsimony, yes.
  - GuiA 8y ago
    Flight has been evolved independently 4 times, gliding much more - how does that square with the principle of parsimony? (ie, if we hadn’t discovered pterosaurs yet, we could make the argument that flight evolved 3 times and probably not more due to the principle of parsimony, but we would be wrong)
    - cwmma 8y ago
      the principle of parsimony is just that, given equal evidence one way or the other, the simpler explanation (flight only evolved 1 time in birds) is more likely then the more complex one (birds gained flight, lost it, then gained it again). The fact that there are only 4 times it's happened that we know about is just evidence that it's a fairly rare thing to evolve.
      - monocasa 8y ago
        But given that it evolved once in birds, after an event that wiped out all of the flying animals, wouldn't the principle of parsimony imply that birds have the lowest barrier to gaining it again to take advantage of that now empty niche?
        dekhn 8y ago
        that depends on how you think loss of function and gain of function works at the phenotype level. For example, I choose to interpret these sorts of situations in the way you do: birds that lost flight still had 99% of the flight capability, being maintained under functional selection for other uses, and so only a small amount of change would be required to regain the ability.
dekhn 8y ago
Basically, you can't take any science reporting major media at face value. The headlines are written as click-bait, and typically in a non-scientific fashion. Some scientists are also prone to releasing catchy PR that misinterprets their results.
- ISL 8y ago
  Most of us natively write anti-clickbait titles. Though it is rarely cited, my favorite paper that I've co-authored is: Indirect Evidence for Lévy Walks in Squeeze Film Damping: https://arxiv.org/abs/1005.4926 https://arxiv.org/abs/1005.4926 It could have alternatively been titled: "Holy crap! Did you know that high-vacuum gas particles trapped between two walls follow fractal paths?!"
  - ChuckMcM 8y ago
    "You won't believe where these high vacuum particles go when they move, or how they get there!"
    - mromanuk 8y ago
      “The walls hate these particles, they can move in fractal ways, you can learn the secret, too”
    - kevin_thibedeau 8y ago
      Bait me with how this affects my car insurance and you've got a click.
      - jonbarker 8y ago
        These four tech giants are upending this centuries old industry... with quantum entanglement.
    - jonbarker 8y ago
      A light wave got sucked into a black hole, you won't believe what happened next! I predict a new meme theme of taboola/outbrain style headlines that are actually semi-accurate sciencey clickbait titles. Genius!
taeric 8y ago
To be fair, the headline is not that they reevolved the ability, but that they had to relearn flight. I was expecting it to say more that many of the strategies that were dominate for flight died off. I was guessing dominate air currents higher up, possibly something crazy like a change in dominate gasses. Point being, same basic birds. Just new advantages steering dominate flight patterns. Not a new mechanism of flight. (Which, yeah, I guess that is all part and parcel of evolution...)
- lomnakkus 8y ago
  I'm not a native English speaker, but AFAIUI "learning" is typically used for individuals and not a species? I think I've seen it used before about species, but it seems to imply some sort of teleology which is decidedly not what happens in evolution. (Though it sometimes might seem like it does!)
  - yonoataraxia 8y ago
    This is more of a semantic discussion: after a while, there will be individuals with better strategies to survive and reproduce (this is the implicit teleology of evolution: living things live on, dead things go extinct). You don't even need someone giving this orders because we define living things as those who live (research communities can't even agree on the definition of life - see viruses). Our words imply specific meaning. I guess you mean that there is another meaning in the word "learning" in that context: That the species follows a specific purpose. But what is the species? The aggregation of all individuals of some kind (the research community can't even agree on a definition for "species"). Some individuals will do stuff or become something (due to genetic modifications) that gives them more resources or better reproduction rates - sometimes individuals will learn and teach it to their offspring. If it's a good strategy, the species will contain a lot of individuals who acquired this strategy. So I guess "learning" is accurate enough for common usage.
    - lomnakkus 8y ago
      Yeah, I guess I was just a bit surprised by "learning" because it does sort of imply "learning by experience" which isn't really a thing when it comes to evolution. I do agree, it's probably just a bit "too semantics", though I do feel it pretty important in science reporting to be as accurate as possible and to try to avoid fostering misconceptions as far as possible. (Let's face it, popular science reporting doesn't have a great record on this. Hell, even university PR departments[1] are culpable.) [1] It's amazing that there even is such a thing, but I guess we just have to deal.
lomnakkus 8y ago
Yes. I know nothing about the evolutionary origin/path of the chicken except that it's a "flightless dinosaur". It certainly has "reduced flight capacity", but given evolutionary time and pressure, it certainly doesn't seem like a controversial idea that chickens -- given the right selective pressure -- could evolve in a direction towards being fully flighted dinos again...?
- jammi 8y ago
  Chickens can perform short flights, but from my limited observations it seems like the stamina is the main limiting factor for them. They've however clearly evolved from fully flight-capable birds, but the now-extinct Moa however might have been a different story: https://en.wikipedia.org/wiki/Moa https://en.wikipedia.org/wiki/Moa
  - lomnakkus 8y ago
    Oh, yes, there are evolutionary dead ends, but e.g. the Moa (or even the Dodo[1]) basically evolved for really long without any evolutionary pressure towards avoiding "enemies" and thus was stuck in a local optimum with no way out. Still ~25 seconds of sustained flight, just about the record for a chicken, I think seems like not-evolutionary-dead-end-enough to my untrained eye. :). YMMV. [1] AFAIUI, it was humans that ultimately drove it to extiction, but it could have been any invasive species that would kill bird-like thigs. Maybe I'm wrong on that.
subleq 8y ago
What are the 4 times that flight has evolved?
- VladimirGolovin 8y ago
  Insects, pterosaurs, birds, and bats. https://en.wikipedia.org/wiki/Flying_and_gliding_animals https://en.wikipedia.org/wiki/Flying_and_gliding_animals Here's a good picture that highlights the differences: https://en.wikipedia.org/wiki/File:Homology.jpg https://en.wikipedia.org/wiki/File:Homology.jpg
- deleted 8y ago
  [deleted]
- pfdietz 8y ago
  That's powered flight, btw. Gliding evolves much more easily.
bjd2385 8y ago
I liked the article's statement that "there were no more perches." Is that to say, then, that even birds that "perch" refused to do so on cliffs? Certainly, not all of the trees perished as well.

by cwmma 8y ago

robbrown451 8y ago

But this time they wouldn't have to evolve it from scratch. It's not hard to imagine a bird such as an ostrich evolving into a flight capable bird, especially if there were no existing flighted birds to compete with. They have elaborate feathered wings, so the biggest change needed is probably just to be smaller. Probably 99.9% of the DNA necessary for flight is already there, it just needs to be regulated a bit differently. This would even be true in birds like kiwis or emus, whose wings are much smaller and vestigial.

GuiA 8y ago

It would certainly be a fantastic discovery, but would it be that surprising? The amount of knowledge we can infer from the fossil record is infinitesimal compared to all that actually happened; and while going from 0 instances of an event to 1 is notable (it tells us that “it can happen”), so is 1 to 2 (it tells us that “it can happen more than once”), but is 4 to 5 that crazy?

dekhn 8y ago
Under the mostly accepted principle of parsimony, yes.
- GuiA 8y ago
  Flight has been evolved independently 4 times, gliding much more - how does that square with the principle of parsimony? (ie, if we hadn’t discovered pterosaurs yet, we could make the argument that flight evolved 3 times and probably not more due to the principle of parsimony, but we would be wrong)
  - cwmma 8y ago
    the principle of parsimony is just that, given equal evidence one way or the other, the simpler explanation (flight only evolved 1 time in birds) is more likely then the more complex one (birds gained flight, lost it, then gained it again). The fact that there are only 4 times it's happened that we know about is just evidence that it's a fairly rare thing to evolve.
    - monocasa 8y ago
      But given that it evolved once in birds, after an event that wiped out all of the flying animals, wouldn't the principle of parsimony imply that birds have the lowest barrier to gaining it again to take advantage of that now empty niche?
      - dekhn 8y ago
        that depends on how you think loss of function and gain of function works at the phenotype level. For example, I choose to interpret these sorts of situations in the way you do: birds that lost flight still had 99% of the flight capability, being maintained under functional selection for other uses, and so only a small amount of change would be required to regain the ability.

dekhn 8y ago

Basically, you can't take any science reporting major media at face value. The headlines are written as click-bait, and typically in a non-scientific fashion. Some scientists are also prone to releasing catchy PR that misinterprets their results.

ISL 8y ago
Most of us natively write anti-clickbait titles. Though it is rarely cited, my favorite paper that I've co-authored is: Indirect Evidence for Lévy Walks in Squeeze Film Damping: https://arxiv.org/abs/1005.4926 https://arxiv.org/abs/1005.4926 It could have alternatively been titled: "Holy crap! Did you know that high-vacuum gas particles trapped between two walls follow fractal paths?!"
- ChuckMcM 8y ago
  "You won't believe where these high vacuum particles go when they move, or how they get there!"
  - mromanuk 8y ago
    “The walls hate these particles, they can move in fractal ways, you can learn the secret, too”
  - kevin_thibedeau 8y ago
    Bait me with how this affects my car insurance and you've got a click.
    - jonbarker 8y ago
      These four tech giants are upending this centuries old industry... with quantum entanglement.
  - jonbarker 8y ago
    A light wave got sucked into a black hole, you won't believe what happened next! I predict a new meme theme of taboola/outbrain style headlines that are actually semi-accurate sciencey clickbait titles. Genius!

taeric 8y ago

To be fair, the headline is not that they reevolved the ability, but that they had to relearn flight. I was expecting it to say more that many of the strategies that were dominate for flight died off. I was guessing dominate air currents higher up, possibly something crazy like a change in dominate gasses. Point being, same basic birds. Just new advantages steering dominate flight patterns. Not a new mechanism of flight. (Which, yeah, I guess that is all part and parcel of evolution...)

lomnakkus 8y ago
I'm not a native English speaker, but AFAIUI "learning" is typically used for individuals and not a species? I think I've seen it used before about species, but it seems to imply some sort of teleology which is decidedly not what happens in evolution. (Though it sometimes might seem like it does!)
- yonoataraxia 8y ago
  This is more of a semantic discussion: after a while, there will be individuals with better strategies to survive and reproduce (this is the implicit teleology of evolution: living things live on, dead things go extinct). You don't even need someone giving this orders because we define living things as those who live (research communities can't even agree on the definition of life - see viruses). Our words imply specific meaning. I guess you mean that there is another meaning in the word "learning" in that context: That the species follows a specific purpose. But what is the species? The aggregation of all individuals of some kind (the research community can't even agree on a definition for "species"). Some individuals will do stuff or become something (due to genetic modifications) that gives them more resources or better reproduction rates - sometimes individuals will learn and teach it to their offspring. If it's a good strategy, the species will contain a lot of individuals who acquired this strategy. So I guess "learning" is accurate enough for common usage.
  - lomnakkus 8y ago
    Yeah, I guess I was just a bit surprised by "learning" because it does sort of imply "learning by experience" which isn't really a thing when it comes to evolution. I do agree, it's probably just a bit "too semantics", though I do feel it pretty important in science reporting to be as accurate as possible and to try to avoid fostering misconceptions as far as possible. (Let's face it, popular science reporting doesn't have a great record on this. Hell, even university PR departments[1] are culpable.) [1] It's amazing that there even is such a thing, but I guess we just have to deal.

lomnakkus 8y ago

Yes. I know nothing about the evolutionary origin/path of the chicken except that it's a "flightless dinosaur". It certainly has "reduced flight capacity", but given evolutionary time and pressure, it certainly doesn't seem like a controversial idea that chickens -- given the right selective pressure -- could evolve in a direction towards being fully flighted dinos again...?

jammi 8y ago
Chickens can perform short flights, but from my limited observations it seems like the stamina is the main limiting factor for them. They've however clearly evolved from fully flight-capable birds, but the now-extinct Moa however might have been a different story: https://en.wikipedia.org/wiki/Moa https://en.wikipedia.org/wiki/Moa
- lomnakkus 8y ago
  Oh, yes, there are evolutionary dead ends, but e.g. the Moa (or even the Dodo[1]) basically evolved for really long without any evolutionary pressure towards avoiding "enemies" and thus was stuck in a local optimum with no way out. Still ~25 seconds of sustained flight, just about the record for a chicken, I think seems like not-evolutionary-dead-end-enough to my untrained eye. :). YMMV. [1] AFAIUI, it was humans that ultimately drove it to extiction, but it could have been any invasive species that would kill bird-like thigs. Maybe I'm wrong on that.

subleq 8y ago

What are the 4 times that flight has evolved?

VladimirGolovin 8y ago
Insects, pterosaurs, birds, and bats. https://en.wikipedia.org/wiki/Flying_and_gliding_animals https://en.wikipedia.org/wiki/Flying_and_gliding_animals Here's a good picture that highlights the differences: https://en.wikipedia.org/wiki/File:Homology.jpg https://en.wikipedia.org/wiki/File:Homology.jpg
deleted 8y ago
[deleted]
pfdietz 8y ago
That's powered flight, btw. Gliding evolves much more easily.

bjd2385 8y ago

I liked the article's statement that "there were no more perches." Is that to say, then, that even birds that "perch" refused to do so on cliffs? Certainly, not all of the trees perished as well.