Only mammals and birds are sentient, according to Nick Humphrey

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Only mammals and birds are sentient, according to neuroscientist Nick Humphrey’s theory of consciousness, recently explained in “Sentience: The invention of consciousness”.

In 2023, Nick Humphrey published his book Sentience: The invention of consciousness (S:TIOC). In this book he proposed a theory of consciousness that implies, he says, that only mammals and birds have any kind of internal awareness.

His theory of consciousness has a lot in common with the picture of consciousness is described in recent books by two other authors, neuroscientist Antonio Damasio and consciousness researcher Anil Seth. All three agree on the importance of feelings, or proprioception, as the evolutionary and experiential base of sentience. Damasio and Seth, if I recall correctly, each put a lot of emphasis on homeostasis as a driving evolutionary force. All three agree sentience evolved as an extension of our senses–touch, sight, hearing, and so on. But S:TIOC is a bolder book which not only describes what we know about the evolutionary base of consciousness but proposes a plausible theory coming as close as can be to describing what it is short of actually solving Chalmers’ Hard Problem.

Read more:
https://forum.effectivealtruism.org/posts/AvubGwD2xkCD4tGtd/only-mammals-and-birds-are-sentient-according-to

 

Decapitation in Rats: Latency to Unconsciousness and the ‘Wave of Death’

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The question whether decapitation is a humane method of euthanasia in awake animals is being debated. To gather arguments in this debate, obsolete rats were decapitated while recording the EEG, both of awake rats and of anesthetized rats. Following decapitation a fast and global loss of power of the EEG was observed; the power in the 13–100 Hz frequency band, expressing cognitive activity, decreased according to an exponential decay function to half the initial value within 4 seconds. Whereas the pre-decapitation EEG of the anesthetized animals showed a burst suppression pattern quite different from the awake animals, the power in the postdecapitation EEG did not differ between the two groups. This might indicate that either the power of the EEG does not correlate well with consciousness or that consciousness is briefly regained in the anesthetized group after decapitation. Remarkably, after 50 seconds (awake group) or 80 seconds (anesthetized group) following decapitation, a high amplitude slow wave was observed. The EEG before this wave had more power than the signal after the wave. This wave might be due to a simultaneous massive loss of membrane potentials of the neurons. Still functioning ion channels, which keep the membrane potential intact before the wave, might explain the observed power difference. Two conclusions were drawn from this experiment. It is likely that consciousness vanishes within seconds after decapitation, implying that decapitation is a quick and not an inhumane method of euthanasia. It seems that the massive wave which can be recorded approximately one minute after decapitation reflects the ultimate border between life and death. This observation might have implications in the discussions on the appropriate time for organ donation.

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A Brain Implant that Automatically Detects and Kills Pain?

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It’s basically a tag-team of spy and sleeper agent. The “spy” listens to electrical chatter in a brain region that processes pain—along with dozens of other tasks—and decodes it in real time. Once it detects an electrical signal that suggests “pain found,” it sends the information to the “sleeper agent,” a computer chip implanted in the front part of the brain. The chip then automatically triggers a light beam to stimulate the region, activating neurons that can override pain signals.

Sources: https://singularityhub.com/2021/06/29/a-new-brain-implant-automatically-detects-and-kills-pain-in-real-time/

https://www.nature.com/articles/s41551-021-00736-7

https://www.eurekalert.org/news-releases/789517

 

 

An empirical investigation of hedonistic accounts of animal welfare

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“Many scientists studying animal welfare appear to hold a hedonistic concept of welfare -whereby welfare is ultimately reducible to an animal’s subjective experience. […] analysis showed welfare judgments depended on the objective features of the animal’s life more than they did on how the animal was feeling: a chimpanzee living a natural life with negative emotions was rated as having better welfare than a chimpanzee living an unnatural life with positive emotions. We also found that the supposedly more purely psychological concept of happiness was also influenced by normative judgments about the animal’s life. For chimpanzees with positive emotions, those living a more natural life were rated as happier than those living an unnatural life. Insofar as analyses of animal welfare are assumed to be reflective of folk intuitions, these findings raise questions about a strict hedonistic account of animal welfare. More generally, this research demonstrates the potential utility of using empirical methods to address conceptual problems in animal welfare and ethics.”

https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0193864

List of Animals That Have Passed the Mirror Test

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When conducting the mirror test, scientists place a visual marking on an animal’s body, usually with scentless paints, dyes, or stickers. They then observe what happens when the marked animal is placed in front of a mirror. The researchers compare the animal’s reaction to other times when the animal saw itself in the mirror without any markings on its body.

Animals that pass the mirror test will typically adjust their positions so that they can get a better look at the new mark on their body, and may even touch it or try to remove it. They usually pay much more attention to the part of their body that bears a new marking.

Currently, nine non-human animal species pass the mirror test. Not all individuals of each species pass, but many do.

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The HHHHHMM (H5M2) Quality of Life Scale

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“The HHHHHMM (H5M2) Quality of Life Scale provides guidelines for the assessment of a pet so that pet owners can maintain a rewarding relationship that nurtures the human–animal bond, while being confident that the pet is well enough to justify prolonging life. This Quality of Life Scale will relieve guilt feelings and engender the support of the veterinary team to actively help in the care and decision making for Pawspice patients. I feel that it is ethical to prolong a life worth living. On the other hand, I feel that it is not ethical to prolong death for our patients.”