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err, I maybe hugely mistaken but is this an example of a real life of the following joke: "a scientist had this experiment going wherein everytime he rung a bel

err, I maybe hugely mistaken but is this an example of a real life of the following joke: "a scientist had this experiment going wherein everytime he rung a bell the grasshopper would jump. He clips one of the grasshopper's legs and rings the bell to see if the grasshopper would still jump and it did. He repeated the clipping process till the grasshopper had no legs. He wondered if it would still jump ... and it did not. He muttered to himself that hence that proves grasshoppers use their legs to hear" am wondering it this is an example of a teleological thinking?

phirus 4y ago
Yes "random walk" is not a strategy, it is a model. This article basically just says:"Jumping bean motion can be modeled with random walk", which isn't really suprising.
- ars 4y ago
  Yah, this article is basically nonsense. The beans jump more when hot, and less when cold, meaning they are more likely to stay put when jumping into the shade, and if too hot they'll keep jumping.
  - yipbub 4y ago
    "These results suggest that diffusive motion [random walks] in Mexican jumping beans does not optimize for finding shade quickly," the authors concluded. "Rather, Mexican jumping beans use a strategy that minimizes the chances of never finding shade when shade is sparse."
    - jameshart 4y ago
      I’m not sure what alternative strategy they are hypothesizing that would find shade more quickly, though? it seems like the bugs have only one motor function - move in a random direction - and only one input sensor - temperature. What other strategies are available to them than random walk with a probability of movement based on a function of temperature and time?
      - mhb 4y ago
        I don't know either, but is it possible they are concluding that the bugs have only the function "move in a random direction" based on their observations? If the bugs had the functions 1) move in one direction and 2) turn, then they might have observed a circular or spiral path.
        jameshart 4y ago
        Put a blindfolded human in a zorb on an uneven patch of desert and I would be impressed if they could manage more than one bounce in the same direction in a row. Not sure what mechanism would enable a jumping bean to reliably bounce ‘forwards’.
    - SamBam 4y ago
      Right, but that conclusion is teleological. First, they have no evidence that evolution could create a jumping bean that jumps in a straight line. It seems that the direction the bean moves is a function of the uncurling larvae but also the shape of the bean. Possibly such a movement could have evolved, but the authors are presenting this like the random walk improved the larvae's fitness function. Second, the conclusion that a straight line would find shade quickest, but only for a small percentage of larvae, is obvious and doesn't result in anything scientifically new. Of course if you draw straight lines from any point in all direction, the straight lines that happened to intersect with the shade will be the fastest path to the shade. But just as obviously, heading in a straight line in a random direction is not the most efficient way to find shade. If they had the freedom to evolve any search strategy possible, there are plenty of search strategies that will uncover shade faster than a random walk. But the larva don't have the ability to select any search strategy they want, they're blind and have no senses besides their current temperature. They have no way of knowing which direction they're facing. Therefore a random walk is simply all that is available to them, it's not a strategy.
- ilija139 4y ago
  Exactly! Many motions in nature can be modeled as either Brownian motion or Lévy flight.
- amatic 4y ago
  Jumping randomly(edit:in a random direction) when it is too hot is a strategy. And apparently good enough for survival of this species. The bacterium e. Coli uses a similar, or identical strategy of turning("tumbling") in a random direction when the environment conditions are not favorable, and then running straight while the conditions are good. You can guide a blindfolded person to a goal of your choosing just by telling them "hot" or "cold". Maybe the name of the strategy should be "directed random walk".
  - ballenf 4y ago
    Isn't it only a strategy if you've established that they are capable of movement in direct line? Otherwise the most you could say is natural selection selected for shell shape that produces random walks. I.e., it's a strategy at the species scale, but not the individual scale. But, maybe that's my mistake of not knowing how these words are used in biology.
    - amatic 4y ago
      It's not the shell that produces random walks, it's the larva of a moth living inside the bean. The larva cannot see the environment, it can sense the temperature, so jumping in a random direction is a means (or a strategy) of the larva with the goal of achieving optimal temperature. It works well in their environment, because the temperature rises if they are exposed to direct sunlight, and a few jumps in a random direction might just get them to shade to a lower temperature. In the shade, they stop jumping.
    - TeMPOraL 4y ago
      "Strategy" makes clear sense for humans. A group of people could think some problem through and adopt a strategy to solve it. For any other life we know of, it quickly stops being meaningful. We may sometimes say that cats or dogs or chimpanzees adopt strategies, because we often like to talk about them as agents. But as we move towards less complex/intelligent forms of life, it quickly becomes clear that we're only ever dealing with biased dice throws. Point being, I wouldn't worry too much about "having a strategy" vs. "natural selection selecting for". It's only ever the latter - perhaps with exception of humans, but that's up to philosophers to figure out.
- kilgnad 4y ago
  Wrong. The model CAN be characterized as a strategy. Why? Because there are better strategies that can be executed. A model is just a description, a strategy is a method for winning. Some methods are better then others. Given zero information about your surroundings other then the fact of whether you are currently in a shade or currently not in a shade traveling in a straight line is a mathematically better strategy. Why? Because random walk includes the possibility of going back to the same place of where there is no shade while traveling in a straight line guarantees every move is a new location.
jacquesm 4y ago
> He muttered to himself that hence that proves grasshoppers use their legs to hear Not quite, but the location of the grasshoppers hearing organ is actually quite close to the legs!
- dotancohen 4y ago
  Many women would say the same about many men, who often don't hear a word that they are saying!
- DonaldFisk 4y ago
  In crickets, which together with grasshoppers are in the order Orthoptera, the hearing organs are actually on the legs: https://en.wikipedia.org/wiki/Cricket_(insect) https://en.wikipedia.org/wiki/Cricket_(insect)

phirus 4y ago

Yes "random walk" is not a strategy, it is a model. This article basically just says:"Jumping bean motion can be modeled with random walk", which isn't really suprising.

ars 4y ago
Yah, this article is basically nonsense. The beans jump more when hot, and less when cold, meaning they are more likely to stay put when jumping into the shade, and if too hot they'll keep jumping.
- yipbub 4y ago
  "These results suggest that diffusive motion [random walks] in Mexican jumping beans does not optimize for finding shade quickly," the authors concluded. "Rather, Mexican jumping beans use a strategy that minimizes the chances of never finding shade when shade is sparse."
  - jameshart 4y ago
    I’m not sure what alternative strategy they are hypothesizing that would find shade more quickly, though? it seems like the bugs have only one motor function - move in a random direction - and only one input sensor - temperature. What other strategies are available to them than random walk with a probability of movement based on a function of temperature and time?
    - mhb 4y ago
      I don't know either, but is it possible they are concluding that the bugs have only the function "move in a random direction" based on their observations? If the bugs had the functions 1) move in one direction and 2) turn, then they might have observed a circular or spiral path.
      - jameshart 4y ago
        Put a blindfolded human in a zorb on an uneven patch of desert and I would be impressed if they could manage more than one bounce in the same direction in a row. Not sure what mechanism would enable a jumping bean to reliably bounce ‘forwards’.
  - SamBam 4y ago
    Right, but that conclusion is teleological. First, they have no evidence that evolution could create a jumping bean that jumps in a straight line. It seems that the direction the bean moves is a function of the uncurling larvae but also the shape of the bean. Possibly such a movement could have evolved, but the authors are presenting this like the random walk improved the larvae's fitness function. Second, the conclusion that a straight line would find shade quickest, but only for a small percentage of larvae, is obvious and doesn't result in anything scientifically new. Of course if you draw straight lines from any point in all direction, the straight lines that happened to intersect with the shade will be the fastest path to the shade. But just as obviously, heading in a straight line in a random direction is not the most efficient way to find shade. If they had the freedom to evolve any search strategy possible, there are plenty of search strategies that will uncover shade faster than a random walk. But the larva don't have the ability to select any search strategy they want, they're blind and have no senses besides their current temperature. They have no way of knowing which direction they're facing. Therefore a random walk is simply all that is available to them, it's not a strategy.
ilija139 4y ago
Exactly! Many motions in nature can be modeled as either Brownian motion or Lévy flight.
amatic 4y ago
Jumping randomly(edit:in a random direction) when it is too hot is a strategy. And apparently good enough for survival of this species. The bacterium e. Coli uses a similar, or identical strategy of turning("tumbling") in a random direction when the environment conditions are not favorable, and then running straight while the conditions are good. You can guide a blindfolded person to a goal of your choosing just by telling them "hot" or "cold". Maybe the name of the strategy should be "directed random walk".
- ballenf 4y ago
  Isn't it only a strategy if you've established that they are capable of movement in direct line? Otherwise the most you could say is natural selection selected for shell shape that produces random walks. I.e., it's a strategy at the species scale, but not the individual scale. But, maybe that's my mistake of not knowing how these words are used in biology.
  - amatic 4y ago
    It's not the shell that produces random walks, it's the larva of a moth living inside the bean. The larva cannot see the environment, it can sense the temperature, so jumping in a random direction is a means (or a strategy) of the larva with the goal of achieving optimal temperature. It works well in their environment, because the temperature rises if they are exposed to direct sunlight, and a few jumps in a random direction might just get them to shade to a lower temperature. In the shade, they stop jumping.
  - TeMPOraL 4y ago
    "Strategy" makes clear sense for humans. A group of people could think some problem through and adopt a strategy to solve it. For any other life we know of, it quickly stops being meaningful. We may sometimes say that cats or dogs or chimpanzees adopt strategies, because we often like to talk about them as agents. But as we move towards less complex/intelligent forms of life, it quickly becomes clear that we're only ever dealing with biased dice throws. Point being, I wouldn't worry too much about "having a strategy" vs. "natural selection selecting for". It's only ever the latter - perhaps with exception of humans, but that's up to philosophers to figure out.
kilgnad 4y ago
Wrong. The model CAN be characterized as a strategy. Why? Because there are better strategies that can be executed. A model is just a description, a strategy is a method for winning. Some methods are better then others. Given zero information about your surroundings other then the fact of whether you are currently in a shade or currently not in a shade traveling in a straight line is a mathematically better strategy. Why? Because random walk includes the possibility of going back to the same place of where there is no shade while traveling in a straight line guarantees every move is a new location.

jacquesm 4y ago

> He muttered to himself that hence that proves grasshoppers use their legs to hear Not quite, but the location of the grasshoppers hearing organ is actually quite close to the legs!

dotancohen 4y ago
Many women would say the same about many men, who often don't hear a word that they are saying!
DonaldFisk 4y ago
In crickets, which together with grasshoppers are in the order Orthoptera, the hearing organs are actually on the legs: https://en.wikipedia.org/wiki/Cricket_(insect) https://en.wikipedia.org/wiki/Cricket_(insect)