Vasco Grilo🔸 comments on Should I have been asked to stop posting about soil animals on Hive’s Slack?

[Vasco Grilo🔸]

Thanks, Will.

I definitely agree I should not be commenting about soil animals on every post about animal welfare. I have not been doing this, although I think most people would like me to bring up soil animals less frequently. I have been trying to focus on more prominent posts, and ones from people who I think may be more open to it.

“if soil animals are conscious”. Nitpick. Certainty of consciousness is not needed. An (expected) welfare per animal-year which is not very low is enough, and I suppose this follows from a probability of sentience which is not very low. By sentience, I mean experiencing positive or negative experiences. Consciousness includes neutral experiences, so it does not necessarily imply sentience.

I am confident effects on soil animals matter for people endorsing something like the welfare ranges presented in Table 8.6 of Bob Fischer’s book about comparing animal welfare across species. I estimate effects on soil animals would still be much larger than those on the target beneficiaries for a welfare per animal-year of exactly 0 for animals with fewer neurons than those considered in Bob’s book, and welfare per animal-year for animals with at least as many neurons as shrimp (the animal with the least neurons for which the welfare range is estimated in the book) proportional to “number of neurons as a fraction of that of humans”^0.19, which explains explains 78.6 % of the variance in the estimates for the welfare range presented in the book. I calculate soil ants and termites have 2.91 and 1.16 times as many neurons as shrimp, so effects on them would still be relevant. I get the following increase in the welfare of soil ants and termites as a fraction of the increase in the welfare of the target beneficiaries for an exponent of 0.19 (the chicken welfare corporate campaigns would decrease animal welfare):

• For cage-free corporate campaigns, −20.4.

• For buying beef, 3.31 M.

• For broiler welfare corporate campaigns, −321.

• For GiveWell’s top charities, 83.6 k.

• For HIPF, 65.5 k.

It is the welfare per animal-year which has to be sufficiently high, but I also think nematodes, the animals with the least neurons, are more than 1 % likely to be sentient. From Andrews (2024):

Given the determinate development of their nervous systems, 30-some years ago it was taken as given that C. elegans are too simple to learn. However, once researchers turned to examine learning and memory in these tiny animals, they found an incredible amount of flexible behavior and sensitivity to experience. C. elegans have short-term and long-term memory, they can learn through habituation (Rankin et al., 1990), association (Wen et al., 1997), and imprinting (Remy & Hobert, 2005). They pass associative learning tasks using a variety of sensory modalities, including taste, smell, sensitivity to temperature, and sensitivity to oxygen (Ardiel & Rankin, 2010). They also integrate information from different sensory modalities, and respond differently to different levels of intoxicating substances, “support[ing] the view that worms can associate a physiological state with a specific experience” (Rankin, 2004, p. R618). There is also behavioral evidence that C. elegans engage in motivational trade-offs. These worms will flexibly choose to head through a noxious environment to gain access to a nutritious substance when hungry enough (Ghosh et al., 2016)—though Birch and colleagues are not convinced this behavior satisfies the marker of motivational trade-offs because it appears that one reflex is merely inhibiting another (Birch et al., 2021, p. 31).

C. elegans are a model organism for the study of nociceptors, and much of what we now know about the mechanisms of nociception comes from studies on this species (Smith & Lewin, 2009). Behavioral responses to noxious stimuli are modulated by opiates, as demonstrated by a study finding that administration of morphine has a dose-dependent effect on the latency of response to heat (Pryor et al., 2007). And, perhaps surprisingly, when the nerve ring that comprises the C. elegans brain was recently mapped, researchers found that different regions of the brain support different circuits that route sensory information to another location where they are integrated, leading to action (Brittin et al., 2021).

Even if we grant the author’s low confidence in nematodes’ having marker five (motivational trade-offs), current science provides ample confidence that nematodes have markers one (nociceptors), two (integrated brain regions), four (responsiveness to analgesics), and seven (sophisticated associative learning). Given high confidence that nematodes have even three of these markers, the report’s methodology [Birch et al. (2021)] would have us conclude that there is “substantial evidence” of sentience in nematodes.