Vasco Grilo🔸 comments on Effects on microorganisms are much larger than those on animals and plants under the assumptions of Rethink Priorities’ mainline welfare ranges?

[Vasco Grilo🔸]

Thanks, Bob.

1. It’s true that we don’t think you can take our methodology and extend it arbitrarily. We grant that it’s very difficult to draw a precise boundary. However, it’s standard to develop a model for a purpose and be wary about its application in a novel context. Very roughly, we take those novel contexts to be ones where the probability of sentience is extremely low.

Would you be able to provide a range for what is “extremely low”, and briefly explain why the probability of sentience of black soldier flies (which are covered in the book) is not extremely low, but that of nematodes is extremely low? I do not know whether your “extremely low” means lower than 10^-10 or 1 %, but I guess the probability of sentience of nematodes may well be over 10 %. 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.

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What we stand behind now is really just what we published in the book

Thanks for clarifying you only stand by what is in the book! I did not know this. Have you communicated this to organisations which have been using the estimates you had shared on EA Forum? I believe the community would find helpful a post where you share what you stand by, and which (expected) welfare ranges you recommend using for comparing welfare across species.

4. It’s understandable that you’re skeptical of our specific welfare range estimates. We, of course, are also skeptical of them. That’s why we have long encouraged people to focus on the order of magnitude estimates.

For 10 of 11 species, my preferred welfare range is less than 10 % of the estimate RP shared on the EA Forum (see last table in my post), so I think the vast majority of these is more than 1 order of magnitude too high.

For what it’s worth, I think you are approaching the Moral Weight Project as something it is not. You are treating it as a general methodology where we can enter some information about the abilities of a system—whatever that system happens to be—and get out moral weights that we can use in expected value calculations for cause prioritization.

I had understood from your past comment that the methodology is not supposed to apply to all biological systems (and I had already understood it was not supposed to apply to non-biological systems). However, I think it makes sense to trust the methodology less if you believe applying it to silkworms or nematodes produces results which are way less trustworthy than those for black soldier flies (which are covered in the book), as these do not seem that different from the former.

[NickLaing]

Quick note Vasco I don’t think their book welfare ranges are substantially different from the ones posted on the forum, so practically I don’t think it’s a big deal for people applying them in CEAd

I retract that Vasco, you are correct—I had a quick glance at pigs and chickens and thought they were about the same, for those smaller animals they are indeed far higher. Perhaps it stems from these sentience numbers in the book being higher for Shrimps and Soldier flies than in the forum posts?

[Vasco Grilo🔸]

Thanks, Nick. Here are the estimates from the book.

The mean for:

• Pigs is 85.4 % (= 0.44/​0.515) of the estimate in RP’s post.

• Chickens is 1.20 (= 0.40/​0.332) times the estimate in RP’s post.

• Carp is 2.70 (= 0.24/​0.089) times the estimate in RP’s post.

• Octopuses is 1.27 (= 0.27/​0.213) times the estimate in RP’s post.

• Shrimp is 8.71 (= 0.27/​0.031) times the estimate in RP’s post.

• Black soldier flies (BSF) is 5.62 (= 0.073/​0.013) times the estimate in RP’s post.

There were significant updates for carp, shrimp, and BSF. @vicky_cox, @Neil_Dullaghan🔹 , and @Vince Mak 🔸, you may want to consider the welfare ranges from Bob’s book instead of those from RP’s post, and stop using the value from RP’s post respecting silkworms to model the benefits of interventions targeting farmed arthropods. Bob said “What we [RP] stand behind now is really just what we published in the book”, and this does not have estimates for the welfare range of larvae.

The higher values for shrimp and BSF also make me think one would obtain larger welfare ranges applying the book’s methodology to less complex organisms (although I know it is not supposed to be extended).

I am not sure whether RP stands by the book’s means or medians. Could you clarify this, Bob? In any case, they do not differ much.