Hi Hannah and Sagar,

You may be interested in my post Total number of neurons and welfare of animal populations. I estimate soil ants, termites, springtails, mites, and nematodes together have 413 M (= 1.76*10^23/(4.26*10^14)) times as many neurons as farmed black soldier fly (BSF) larvae and mealworms together, and 2.03 billion (= -7.00*10^15/(-3.44*10^6)) times as much welfare in total for welfare per animal-year proportional to "number of neurons as a fraction of that of humans"^0.5. As illustrated below, the ratio is huge for other exponents besides 0.5.

Thank you for the support, Fai!

Thanks for sharing. I did not know the post had been crossposted to LessWrong.

Thanks for sharing, Axelle!

🐔 I’m now working on a book about “turbochickens”, the Better/European Chicken Commitment, and the global broiler industry as a symbol of industrial animal agriculture reaching its limits – scheduled for publication in French next spring.

Are you also planning to publish the book in English?

Thanks for the kind words, Damin!

Thanks for clarifying, Kestrel. I would be curious to know what makes you unconvinced about nematodes in light of Andrews (2024) and Becerra at al. (2023).

Thanks, Kestrel.

I suspect that there exists a belief that below a certain threshold there is no consciousness or capacity for welfare - a discontinuity - and thus animals such as nematodes are out of scope.

Note many people rule out animals way more cognitively sophisticated than nematodes postulating such a discontinuity. Bryan Caplan said the graph below "nicely summarizes my [Bryan's] broader view".

I would not be surprised if the absolute value of the welfare per animal-year decreased much faster than exponentially with the number of neurons for a sufficiently low number of neurons. However, I assume an exponential decrease up to the number of neurons of nematodes given the large uncertainty about whether there is such a transition, and the number of neurons for which it would happen. I believe there should be some models according to which the welfare per animal-year does not abruptly go to 0, and the expected welfare per animal-year will be determine by such models.

I would say they have at least a 10 % chance of being sentient. From the article “All animals are conscious”: Shifting the null hypothesis in consciousness science by Kristin Andrews (here is a crosspost of Faunalytics' summary of it):

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.

Furthermore, the welfare of soil animals would still dominate even if all animals with fewer neurons than shrimps, which are the ones with the least neurons covered in Bob's book, had a welfare per animal-year of exactly 0. This would imply a total welfare of exactly 0 for farmed BSF larvae and mealworms, and soil springtails, mites, and nematodes. Yet, soil ants and termites would still be considered. I calculate they have 2.91 and 1.16 times as many neurons as shrimps. Below is a graph comparing the welfare of soil ants and termites with that of other animal populations. I have not set the welfare of farmed BSF and mealworms to 0, but doing this would only slightly reinforce my point.

Sorry, I don't think I have relevant expertise to assess such empirical claims (which is why I focus more on hypotheticals).

Note many do not engage with my empirical claims about effects on soil animals for philosophical reasons ("that assumes utilitarianism!"), and assessing these is a comparative advantage you have. Moreover, in the effective altruism community, some people initially concluded that targeting farmed animals increases animal welfare very cost-effectively based on classical utilitarian reasons, and I expect many of those people to depart from classical utilitarianism after realising it plus empirical evidence point towards prioritising soil animals much more than farmed animals. People with a scout mindset, and not invested in any particular way of increasing animal welfare could be in a better place to assess the extent to which such departures from classical utilitarianism are post hoc justifications, eventually in the form of empirical arguments which are seldomly investigated.

As a concrete example of philosophical arguments being important, @Wladimir J. Alonso, the founder and innovation director of the Welfare Footprint Institute (WFI), values averting intense suffering more than is justified by its intensity. Some people, not necessarily Wladimir, endorse this so much that they would prefer averting 1 h of excruciating pain over an infinite amount of annoying pain, and would never consider effects on soil animals given other animals can experience much more intense suffering.

I set the welfare range as a fraction of that of humans to “number of neurons as a fraction of that of humans”^“exponent of the number of neurons”

The results for this can be used for proxies besides the number of neurons (for example, number of neurons in the forebrain). If one thinks the welfare range as a fraction of that of humans is w = "proxy as a fraction of that of humans"^"exponent of the proxy", and that "proxy as a fraction of that of humans" = "number of neurons as a fraction of that of humans"^k, w = "number of neurons as a fraction of that of humans"^(k*"exponent of the proxy"). So the results based on the new proxy for "exponent of the proxy" would be the same as my results based on the number of neurons for "exponent of the number of neurons" = k*"exponent of the proxy".

I'd be excited for more people to look into these claims!

Good to know! I think highlighting the importance of the topic is one way of getting more people to investigate it ;).