Sign in with Facebook
Russell Powell’s Followers (3)
Russell Powell
Website
More books by Russell Powell…
“In order to avoid the deafening of conspecifics, some bats employ a jamming avoidance response, rapidly shifting frequencies or flying silent when foraging near conspecifics. Because jamming is a problem facing any active emission sensory system, it is perhaps not surprising (though no less amazing) that similar jamming avoidance responses are deployed by weakly electric fish. The speed of sound is so fast in water that it makes it difficult for echolocating whales to exploit similar Doppler effects. However, the fact that acoustic emissions propagate much farther and faster in the water medium means that there is less attenuation of ultrasound in water, and thus that echolocation can be used for broader-scale 'visual' sweeping of the undersea environment.
These constraints and trade-offs must be resolved by all acoustic ISMs, on Earth and beyond. There are equally universal anatomical and metabolic constraints on the evolvability of echolocation that explain why it is 'harder' to evolve than vision. First, as noted earlier, a powerful sound-production capacity, such as the lungs of tetrapods, is required to produce high-frequency emissions capable of supporting high-resolution acoustic imaging. Second, the costs of echolocation are high, which may limit acoustic imaging to organisms with high-metabolisms, such as mammals and birds. The metabolic rates of bats during echolocation, for instance, are up to five times greater than they are at rest. These costs have been offset in bats through the evolutionarily ingenious coupling of sound emission to wing-beat cycle, which functions as a single unit of biomechanical and metabolic efficiency. Sound emission is coupled with the upstroke phase of the wing-beat cycle, coinciding with contraction of abdominal muscles and pressure on the diaphragm. This significantly reduces the price of high-intensity pulse emission, making it nearly costless. It is also why, as any careful crepuscular observer may have noticed, bats spend hardly any time gliding (which is otherwise a more efficient means of flight).”
― Contingency and Convergence: Toward a Cosmic Biology of Body and Mind
These constraints and trade-offs must be resolved by all acoustic ISMs, on Earth and beyond. There are equally universal anatomical and metabolic constraints on the evolvability of echolocation that explain why it is 'harder' to evolve than vision. First, as noted earlier, a powerful sound-production capacity, such as the lungs of tetrapods, is required to produce high-frequency emissions capable of supporting high-resolution acoustic imaging. Second, the costs of echolocation are high, which may limit acoustic imaging to organisms with high-metabolisms, such as mammals and birds. The metabolic rates of bats during echolocation, for instance, are up to five times greater than they are at rest. These costs have been offset in bats through the evolutionarily ingenious coupling of sound emission to wing-beat cycle, which functions as a single unit of biomechanical and metabolic efficiency. Sound emission is coupled with the upstroke phase of the wing-beat cycle, coinciding with contraction of abdominal muscles and pressure on the diaphragm. This significantly reduces the price of high-intensity pulse emission, making it nearly costless. It is also why, as any careful crepuscular observer may have noticed, bats spend hardly any time gliding (which is otherwise a more efficient means of flight).”
― Contingency and Convergence: Toward a Cosmic Biology of Body and Mind
“Even if patients with a severed corpus callosum are in fact harboring two distinct loci of experience, this does not show that they or individuals with normal brains do not harbor many more experiencers within them, because the behaviors and reports elicited in experiments do not speak to that question. As Thomas Nagel points out in one of the first philosophical treatments of the split-brain phenomenon, there is no reason to think that verbalizability, or, we might add, any motor output capacity, is a necessary condition for subjective experience. Because measurable outputs will generally occur at the level of maximal integration - that is, at the level of the organism as a whole - they say rather little about the presence of subjective experience in subsystems that are nested within the main system, whether these subsystems are neuronal networks or even neurons themselves. The notion of nested experiencers may counterintuitive, but if we have learned any lesson from modern science, it is that the range of things that exist and the range of things that are intuitively plausible often fail to overlap. It is probably best, therefore, to remain agnostic as to whether there are nested experiencers within maximally integrated conscious systems.”
― Contingency and Convergence: Toward a Cosmic Biology of Body and Mind
― Contingency and Convergence: Toward a Cosmic Biology of Body and Mind
Is this you? Let us know. If not, help out and invite Russell to Goodreads.
