The Nonlinear Library EA - Research summary: The evolution of nociception in arthropods by abrahamrowe
Apr 17, 2024
14:19
Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: Research summary: The evolution of nociception in arthropods, published by abrahamrowe on April 17, 2024 on The Effective Altruism Forum.
This post is a short summary of A long-read draft assembly of the Chinese mantis (Mantodea: Mantidae: Tenodera sinensis) genome reveals patterns of ion channel gain and loss across Arthropoda, a peer-reviewed, open-access publication in G3: Genes | Genomes | Genetics under a
CC BY license. The paper and supplemental information can be accessed
here. The original paper was written by Jay Goldberg, R. Keating Godfrey, and Meghan Barrett; the research conducted in the paper was funded by Rethink Priorities as part of our research agenda on understanding the welfare of insects on farms.
This post was written by Abraham Rowe and reviewed for accuracy by Jay Goldberg and Meghan Barrett. All information is derived from the Goldberg et al. (2024) publication unless otherwise cited, and some text from the original publication is directly adapted for this summary.
Introduction
Mantids that engage in sexually cannibalistic behaviors (e.g., where the female eats the male during copulation) are often cited as a pinnacle example of insects' lack of pain sensation and, therefore, sentience. In their seminal paper on insect sentience, Eisemann et al.'s (
1984) Do insects feel pain? - A biological view, the authors cite the fact that male mantids continue to mate while being cannibalized as a behavioral indicator of a lack of pain sensation in insects more broadly (
Eisemann et al. 1984). This behavior suggests that male mantids might not even be able to sense, and thus respond reflexively to, the noxious mechanical damage that occurs during the copulatory experience. One mechanism by which animals can sense mechanical damage is through nociceptive ion channels, proteins found in their peripheral sensory neurons. At the time of Eisemann et al.'s publication, insects were not known to have nociceptive ion channels (a fact they also discuss).
It has now been determined that many arthropods (including insects) have nociceptors that perceive chemical, mechanical, and thermal injuries. Indeed, many of their nociceptive ion channels are homologous to mammalian channels (homologous, meaning that the genes for these channels were inherited from a common ancestor to both mammals and insects).
However, whether mantids have these ion channels - thus presenting a challenge to the 'peripheral sensory perception' part of the Eisemann argument against insect pain as demonstrated by male mantid behavior - is not known. Genes can be gained and lost across species.
Finding evidence of the presence or absence of these channels in the genome of a sexually cannibalistic mantid species would be an important first step to understanding the weaknesses or strengths of Eisemann et al.'s claims about how we might interpret their behavior.
Further, by looking at the genes of arthropods across families, we can assess how nociception may have evolved in insects and possibly begin to understand why there is a variance in nociceptive ion channel expression across the arthropods.
This understanding might help us identify what kinds of noxious stimuli are perceived negatively by different insect species in the future as, for instance, some other animals are known to lack certain categories of nociceptors (e.g., cold nociception is lacking in some fish species;
Sneddon 2019). Additionally, gene copy number (how many copies of that gene the species has in its genome) can also play a role in the strength of their response to a noxious stimulus (
Jang et al., 2023; in Drosophila melanogaster). Determining gene copy number could eventually lead us to understand the high degree of variance in response to noxious stimuli among insects. Of course, in all cases, surveying genetic data is on...
This post is a short summary of A long-read draft assembly of the Chinese mantis (Mantodea: Mantidae: Tenodera sinensis) genome reveals patterns of ion channel gain and loss across Arthropoda, a peer-reviewed, open-access publication in G3: Genes | Genomes | Genetics under a
CC BY license. The paper and supplemental information can be accessed
here. The original paper was written by Jay Goldberg, R. Keating Godfrey, and Meghan Barrett; the research conducted in the paper was funded by Rethink Priorities as part of our research agenda on understanding the welfare of insects on farms.
This post was written by Abraham Rowe and reviewed for accuracy by Jay Goldberg and Meghan Barrett. All information is derived from the Goldberg et al. (2024) publication unless otherwise cited, and some text from the original publication is directly adapted for this summary.
Introduction
Mantids that engage in sexually cannibalistic behaviors (e.g., where the female eats the male during copulation) are often cited as a pinnacle example of insects' lack of pain sensation and, therefore, sentience. In their seminal paper on insect sentience, Eisemann et al.'s (
1984) Do insects feel pain? - A biological view, the authors cite the fact that male mantids continue to mate while being cannibalized as a behavioral indicator of a lack of pain sensation in insects more broadly (
Eisemann et al. 1984). This behavior suggests that male mantids might not even be able to sense, and thus respond reflexively to, the noxious mechanical damage that occurs during the copulatory experience. One mechanism by which animals can sense mechanical damage is through nociceptive ion channels, proteins found in their peripheral sensory neurons. At the time of Eisemann et al.'s publication, insects were not known to have nociceptive ion channels (a fact they also discuss).
It has now been determined that many arthropods (including insects) have nociceptors that perceive chemical, mechanical, and thermal injuries. Indeed, many of their nociceptive ion channels are homologous to mammalian channels (homologous, meaning that the genes for these channels were inherited from a common ancestor to both mammals and insects).
However, whether mantids have these ion channels - thus presenting a challenge to the 'peripheral sensory perception' part of the Eisemann argument against insect pain as demonstrated by male mantid behavior - is not known. Genes can be gained and lost across species.
Finding evidence of the presence or absence of these channels in the genome of a sexually cannibalistic mantid species would be an important first step to understanding the weaknesses or strengths of Eisemann et al.'s claims about how we might interpret their behavior.
Further, by looking at the genes of arthropods across families, we can assess how nociception may have evolved in insects and possibly begin to understand why there is a variance in nociceptive ion channel expression across the arthropods.
This understanding might help us identify what kinds of noxious stimuli are perceived negatively by different insect species in the future as, for instance, some other animals are known to lack certain categories of nociceptors (e.g., cold nociception is lacking in some fish species;
Sneddon 2019). Additionally, gene copy number (how many copies of that gene the species has in its genome) can also play a role in the strength of their response to a noxious stimulus (
Jang et al., 2023; in Drosophila melanogaster). Determining gene copy number could eventually lead us to understand the high degree of variance in response to noxious stimuli among insects. Of course, in all cases, surveying genetic data is on...