The Thoughts of a Spiderweb
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cognitive science
By Joshua Sokol
Sin Eater for Quanta Magazine
Joshua Sokol
Print this article
Millions of years ago, a few spiders abandoned the kind of round webs that the word “spiderweb” calls to mind and commenced to concentrate on a fresh strategy. Before, they would wait for prey to become ensnared in their webs and then walk out to retrieve it. Then they began building horizontal nets to use as a fishing platform. Now their modern descendants, the cobweb spiders, dangle gooey threads below, wait until insects walk by and get snagged, and reel their unlucky victims in.
In 2008, the researcher Hilton Japyassú prompted twelve species of orb spiders collected from all over Brazil to go through this transition again. He waited until the spiders wove an ordinary web. Then he snipped its threads so that the silk drooped to where crickets wandered below. When a cricket got hooked, not all the orb spiders could fully pull it up, as a cobweb spider does. But some could, and all at least began to reel it in with their two front gams.
Their capability to recapitulate the ancient spiders’ innovation got Japyassú, a biologist at the Federal University of Bahia in Brazil, thinking. When the spider was confronted with a problem to solve that it might not have seen before, how did it figure out what to do? “Where is this information?” he said. “Where is it? Is it in her head, or does this information emerge during the interaction with the altered web?”
In February, Japyassú and Kevin Laland, an evolutionary biologist at the University of Saint Andrews, proposed a bold response to the question. They argued in a review paper, published in the journal Animal Cognition, that a spider’s web is at least an adjustable part of its sensory apparatus, and at most an extension of the spider’s cognitive system.
This would make the web a model example of extended cognition, an idea very first proposed by the philosophers Andy Clark and David Chalmers in one thousand nine hundred ninety eight to apply to human thought. In accounts of extended cognition, processes like checking a grocery list or rearranging Scrabble tiles in a tray are close enough to memory-retrieval or problem-solving tasks that happen entirely inwards the brain that proponents argue they are actually part of a single, larger, “extended” mind.
Among philosophers of mind, that idea has racked up citations, including supporters and critics. And by its very design, Japyassú’s paper, which aims to export extended cognition as a testable idea to the field of animal behavior, is already stirring up antibodies among scientists. “I got the impression that it was being very careful to check all the boxes for hot topics and controversial topics in animal cognition,” said Alex Jordan, a collective behaviorial scientist at the Max Planck Institute in Konstanz, Germany (who nonetheless supports the idea).
While many disagree with the paper’s interpretations, the probe shouldn’t be confused for a lump of philosophy. Japyassú and Laland propose ways to test their ideas in concrete experiments that involve manipulating the spider’s web — tests that other researchers are excited about. “We can break that machine; we can snap strands; we can reduce the way that animal is able to perceive the system around it,” Jordan said. “And that generates some very direct and testable hypotheses.”
The Mindful Tentacle
The suggestion that some of a spider’s “thoughts” happen in its web fits into a puny but growing trend in discussions of animal cognition. Many animals interact with the world in certain complicated ways that don’t rely on their brains. In some cases, they don’t even use neurons. “We have this romantic notion that big brains are good, but most animals don’t work this way,” said Ken Cheng, who studies animal behavior and information processing at Macquarie University in Australia.
Parallel to the extended cognition that Japyassú sees in spiders, researchers have been gathering examples from elsewhere in the animal kingdom that seem to showcase a related concept, called embodied cognition: where cognitive tasks sprawl outside of the brain and into the figure.
Perhaps the prime example is another eight-legged invertebrate. Octopuses are famously brainy, but their central brain is only a petite part of their jumpy systems. Two-thirds of the harshly five hundred million neurons in an octopus are found in its arms. That led Binyamin Hochner of the Hebrew University of Jerusalem to consider whether octopuses use embodied cognition to pass a chunk of food held in their arms straight to their throats.
For the octopus, with thousands of suckers studding symmetric arms, each of which can arch at any point, building a central mental representation of how to stir seems like a computational nightmare. But experiments display that the octopus doesn’t do that. “The brain doesn’t have to know how to budge this floppy arm,” Cheng said. Rather, the arm knows how to stir the arm.
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Octopus movements are too complicated to be centrally coordinated.
Readings of electrified signals display that when a sucker finds a chunk of food, it sends a wave of muscle activation inward up the arm. At the same time, the base of the arm sends another wave of clenched muscles outward, down the arm. Where the two signals meet each other, the arm makes an elbow — a joint in exactly the right place to reach the mouth.
Yet another related strategy, this one perhaps much more common and less controversial, is that the sensory systems of many animals are tuned in to the parts of the world that are relevant to their lives. Bees, for example, use ultraviolet vision to find flowers that have also evolved ultraviolet markings. That avoids the need to take in lots of data and parse it later. “If you do not have those receptors, that part of the world simply doesn’t exist,” said William Wcislo, a behaviorist at the Smithsonian Tropical Research Institute in Panama.
And then there are animals that show up to offload part of their mental apparatus to structures outside of the neural system entirely. Female crickets, for example, orient themselves toward the calls of the loudest masculines. They pick up the sound using ears on each of the knees of their two front gams. These ears are connected to one another through a tracheal tube. Sound sways come in to both ears and then pass through the tube before interfering with one another in each ear. The system is set up so that the ear closest to the source of the sound will stimulate most strongly.
In crickets, the information processing — the job of finding and identifying the direction that the loudest sound is coming from — shows up to take place in the physical structures of the ears and tracheal tube, not inwards the brain. Once these structures have finished processing the information, it gets passed to the neural system, which tells the gams to turn the cricket in the right direction.
The Brain Constraint
Extended cognition may partly be an evolutionary response to an outsized challenge. According to a rule very first observed by the Swiss naturalist Albrecht von Haller in 1762, smaller creatures almost always devote a larger portion of their figure weight to their brains, which require more calories to fuel than other types of tissue.
Haller’s rule holds across the animal kingdom. It works for mammals from whales and elephants down to mice; for salamanders; and across the many species of ants, bees and nematodes. And in this latter range, as brains request more and more resources from the lil’ creatures that host them, scientists like Wcislo and his colleague William Eberhard, also at the Smithsonian, think fresh evolutionary tricks should arise.
In 2007, Eberhard compared data on the webs built by infant and adult spiders of the same species. The newborns, toughly a thousand times smaller than the adults in some cases, should be under much more pressure from Haller’s rule. As a result, they might be expected to slip up while performing a complicated task. Perhaps the spiderlings would make more mistakes in fastening threads at the correct angles to build a geometrically precise web, among other measures. But their webs seemed “as precise as that of their larger relatives,” Eberhard said. “One of the questions is: How do they get away with that?”
Japyassú’s work offers a possible solution. Just as octopi emerge to outsource information-processing tasks to their tentacles, or crickets to their tracheal tubes, perhaps spiders outsource information processing to objects outside of their figures — their webs.
To test whether this is truly happening, Japyassú uses a framework suggested by the cognitive scientist David Kaplan. If spider and web are working together as a larger cognitive system, the two should be able to affect each other. Switches in the spider’s cognitive state will alter the web, and switches in the web will likewise ripple into the spider’s cognitive state.
Consider a spider at the center of its web, waiting. Many web-builders are near blind, and they interact with the world almost solely through stimulations. Sitting at the hub of their webs, spiders can pull on radial threads that lead to various outer sections, thereby adjusting how sensitive they are to prey that land in those particular areas.
As is true for a tin can telephone, a tighter string is better at passing along stimulations. Tensed regions, then, may showcase where the spider is paying attention. When insects land in tensed areas of the webs of the orb spider Cyclosa octotuberculata, a two thousand ten probe found, the spider is more likely to notice and capture them. And when the experimenters in the same investigate tightened the threads artificially, it seemed to put the spiders on high alert — they rushed toward prey more quickly.
The same sort of effect works in the opposite direction, too. Let the orb spider Octonoba sybotides go greedy, switching its internal state, and it will tighten its radial threads so it can tune in to even petite prey hitting the web. “She tenses the threads of the web so that she can filter information that is coming to her brain,” Japyassú said. “This is almost the same thing as if she was filtering things in her own brain.”
The Thoughts of a Spiderweb, Quanta Magazine
The Thoughts of a Spiderweb
Comments
cognitive science
By Joshua Sokol
Sin Eater for Quanta Magazine
Joshua Sokol
Print this article
Millions of years ago, a few spiders abandoned the kind of round webs that the word “spiderweb” calls to mind and began to concentrate on a fresh strategy. Before, they would wait for prey to become ensnared in their webs and then walk out to retrieve it. Then they began building horizontal nets to use as a fishing platform. Now their modern descendants, the cobweb spiders, dangle goopy threads below, wait until insects walk by and get snagged, and reel their unlucky victims in.
In 2008, the researcher Hilton Japyassú prompted twelve species of orb spiders collected from all over Brazil to go through this transition again. He waited until the spiders wove an ordinary web. Then he snipped its threads so that the silk drooped to where crickets wandered below. When a cricket got hooked, not all the orb spiders could fully pull it up, as a cobweb spider does. But some could, and all at least began to reel it in with their two front gams.
Their capability to recapitulate the ancient spiders’ innovation got Japyassú, a biologist at the Federal University of Bahia in Brazil, thinking. When the spider was confronted with a problem to solve that it might not have seen before, how did it figure out what to do? “Where is this information?” he said. “Where is it? Is it in her head, or does this information emerge during the interaction with the altered web?”
In February, Japyassú and Kevin Laland, an evolutionary biologist at the University of Saint Andrews, proposed a bold reaction to the question. They argued in a review paper, published in the journal Animal Cognition, that a spider’s web is at least an adjustable part of its sensory apparatus, and at most an extension of the spider’s cognitive system.
This would make the web a model example of extended cognition, an idea very first proposed by the philosophers Andy Clark and David Chalmers in one thousand nine hundred ninety eight to apply to human thought. In accounts of extended cognition, processes like checking a grocery list or rearranging Scrabble tiles in a tray are close enough to memory-retrieval or problem-solving tasks that happen entirely inwards the brain that proponents argue they are actually part of a single, larger, “extended” mind.
Among philosophers of mind, that idea has racked up citations, including supporters and critics. And by its very design, Japyassú’s paper, which aims to export extended cognition as a testable idea to the field of animal behavior, is already stirring up antibodies among scientists. “I got the impression that it was being very careful to check all the boxes for hot topics and controversial topics in animal cognition,” said Alex Jordan, a collective behaviorial scientist at the Max Planck Institute in Konstanz, Germany (who nonetheless supports the idea).
While many disagree with the paper’s interpretations, the examine shouldn’t be confused for a chunk of philosophy. Japyassú and Laland propose ways to test their ideas in concrete experiments that involve manipulating the spider’s web — tests that other researchers are excited about. “We can break that machine; we can snap strands; we can reduce the way that animal is able to perceive the system around it,” Jordan said. “And that generates some very direct and testable hypotheses.”
The Mindful Tentacle
The suggestion that some of a spider’s “thoughts” happen in its web fits into a petite but growing trend in discussions of animal cognition. Many animals interact with the world in certain complicated ways that don’t rely on their brains. In some cases, they don’t even use neurons. “We have this romantic notion that big brains are good, but most animals don’t work this way,” said Ken Cheng, who studies animal behavior and information processing at Macquarie University in Australia.
Parallel to the extended cognition that Japyassú sees in spiders, researchers have been gathering examples from elsewhere in the animal kingdom that seem to display a related concept, called embodied cognition: where cognitive tasks sprawl outside of the brain and into the figure.
Perhaps the prime example is another eight-legged invertebrate. Octopuses are famously wise, but their central brain is only a puny part of their jumpy systems. Two-thirds of the toughly five hundred million neurons in an octopus are found in its arms. That led Binyamin Hochner of the Hebrew University of Jerusalem to consider whether octopuses use embodied cognition to pass a lump of food held in their arms straight to their throats.
For the octopus, with thousands of suckers studding symmetric arms, each of which can arch at any point, building a central mental representation of how to budge seems like a computational nightmare. But experiments demonstrate that the octopus doesn’t do that. “The brain doesn’t have to know how to budge this floppy arm,” Cheng said. Rather, the arm knows how to budge the arm.
Share this article
Newsletter
Get Quanta Magazine delivered to your inbox
Octopus movements are too complicated to be centrally coordinated.
Readings of electrified signals display that when a sucker finds a lump of food, it sends a wave of muscle activation inward up the arm. At the same time, the base of the arm sends another wave of clenched muscles outward, down the arm. Where the two signals meet each other, the arm makes an elbow — a joint in exactly the right place to reach the mouth.
Yet another related strategy, this one perhaps much more common and less controversial, is that the sensory systems of many animals are tuned in to the parts of the world that are relevant to their lives. Bees, for example, use ultraviolet vision to find flowers that have also evolved ultraviolet markings. That avoids the need to take in lots of data and parse it later. “If you do not have those receptors, that part of the world simply doesn’t exist,” said William Wcislo, a behaviorist at the Smithsonian Tropical Research Institute in Panama.
And then there are animals that show up to offload part of their mental apparatus to structures outside of the neural system entirely. Female crickets, for example, orient themselves toward the calls of the loudest masculines. They pick up the sound using ears on each of the knees of their two front gams. These ears are connected to one another through a tracheal tube. Sound sways come in to both ears and then pass through the tube before interfering with one another in each ear. The system is set up so that the ear closest to the source of the sound will stimulate most strongly.
In crickets, the information processing — the job of finding and identifying the direction that the loudest sound is coming from — emerges to take place in the physical structures of the ears and tracheal tube, not inwards the brain. Once these structures have finished processing the information, it gets passed to the neural system, which tells the gams to turn the cricket in the right direction.
The Brain Constraint
Extended cognition may partly be an evolutionary response to an outsized challenge. According to a rule very first observed by the Swiss naturalist Albrecht von Haller in 1762, smaller creatures almost always devote a larger portion of their assets weight to their brains, which require more calories to fuel than other types of tissue.
Haller’s rule holds across the animal kingdom. It works for mammals from whales and elephants down to mice; for salamanders; and across the many species of ants, bees and nematodes. And in this latter range, as brains request more and more resources from the little creatures that host them, scientists like Wcislo and his colleague William Eberhard, also at the Smithsonian, think fresh evolutionary tricks should arise.
In 2007, Eberhard compared data on the webs built by infant and adult spiders of the same species. The newborns, toughly a thousand times smaller than the adults in some cases, should be under much more pressure from Haller’s rule. As a result, they might be expected to slip up while performing a sophisticated task. Perhaps the spiderlings would make more mistakes in fastening threads at the correct angles to build a geometrically precise web, among other measures. But their webs seemed “as precise as that of their larger relatives,” Eberhard said. “One of the questions is: How do they get away with that?”
Japyassú’s work offers a possible solution. Just as octopi show up to outsource information-processing tasks to their tentacles, or crickets to their tracheal tubes, perhaps spiders outsource information processing to objects outside of their bods — their webs.
To test whether this is truly happening, Japyassú uses a framework suggested by the cognitive scientist David Kaplan. If spider and web are working together as a larger cognitive system, the two should be able to affect each other. Switches in the spider’s cognitive state will alter the web, and switches in the web will likewise ripple into the spider’s cognitive state.
Consider a spider at the center of its web, waiting. Many web-builders are near blind, and they interact with the world almost solely through stimulations. Sitting at the hub of their webs, spiders can pull on radial threads that lead to various outer sections, thereby adjusting how sensitive they are to prey that land in those particular areas.
As is true for a tin can telephone, a tighter string is better at passing along stimulations. Tensed regions, then, may showcase where the spider is paying attention. When insects land in tensed areas of the webs of the orb spider Cyclosa octotuberculata, a two thousand ten examine found, the spider is more likely to notice and capture them. And when the experimenters in the same explore tightened the threads artificially, it seemed to put the spiders on high alert — they rushed toward prey more quickly.
The same sort of effect works in the opposite direction, too. Let the orb spider Octonoba sybotides go thirsty, switching its internal state, and it will tighten its radial threads so it can tune in to even puny prey hitting the web. “She tenses the threads of the web so that she can filter information that is coming to her brain,” Japyassú said. “This is almost the same thing as if she was filtering things in her own brain.”