Prioritise soil animals over farmed invertebrates?

Vasco Grilo🔸

Prioritise soil animals over farmed invertebrates?

Vasco Grilo🔸

8 min readNov 15, 2025

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shloka 🔸

7mo*

Hi Vasco! I was wondering if you've thought about the effects of land use change on soil nematodes at finer taxonomic resolutions. I think this could be relevant for the following reasons:

There is some variation in neuron counts between nematode species. For example, Mermis negrescens is a grasshopper parasite that has ~1,000 neurons in its ventral nerve cord.
Even though most soil nematodes have similar simple nervous systems, there is significant variation in their life history strategies. The equivalent of r vs K-selected life histories for nematodes is the colonizer-persister scale from 1 to 5. On the lower extreme, colonizers (roughly comparable to r-strategists) have high reproduction rates and experience large fluctuations in population density under uncertain environmental conditions. The Rhabditid family of nematodes, which includes C. elegans, is one such example. On the higher extreme, persisters (roughly comparable to K-strategists) have low reproduction rates and maintain population size in more stable conditions. The Thornematidae and Nygolaimidae families are examples of persisters. Of course, many nematode families fall somewhere in the middle. The colonizer-persister scale also probably obscures other important differences between nematode species, like variation in lifespan. I'm wondering if all this variation suggests that all soil nematodes shouldn't be thought of as a single group in such welfare analyses because some might have much lower welfare than others.
Soil nematodes also have ecologically diverse roles: plant parasites, predators, animal parasites, and bacterial/fungal feeders. Land use change will probably differentially impact these functional groups (as well as colonizers vs. persisters). For example, this study suggests that intensively managed land might produce disturbance regimes that select for colonizers, who probably have worse lives than persisters. And here's another study that observed decreased predator nematodes population abundances after urbanization, which might be bad if predators have particularly good lives. If these studies are right, it seems really important to take local selective conditions into account to avoid land use changes that cause harm.

Thanks for your post, and I apologize if you've addressed this elsewhere!

Vasco Grilo🔸

7mo

Welcome to the EA Forum, Shloka! Thanks for the great comment. I strongly upvoted it.

I have not looked into the effects of land use change on different groups of nematodes. From Table 1 of van den Hoogen et al. (2019), which is below, the most abundant soil nematodes are bacterivores and herbivores, so I speculate effects on these are the most important. However, I agree a given land use change may increase the welfare of nematodes of a given type, but decrease that of ones of a different type. This strengthens my conclusion that the priority is research informing how to increase the welfare of soil animals, not pursuing whatever land use change interventions naively seem to achieve that the most cost-effectively.

Jim Buhler

7mo*

Interesting argument, thanks Vasco! Fwiw, I agree with all the high-level claims except maybe with this one (or at least with its level of precision):

I conclude electrically stunning farmed shrimp changes the welfare of soil animals more than it increases the welfare of shrimps if it results in the replacement of more than 0.0374 % of the consumption of the affected farmed shrimp by farmed fish. I can easily see this happening for even a slight increase in the cost of shrimp.

I think maybe we should be more uncertain about inter-species tradeoffs than you seem to be, here. Maybe there's a plausible world where shrimp welfare matters astronomically more than that of soil animals, to the point where this outbalances the fact that the latter are much more numerous. I currently don't know enough about the topic to find this less (or more) likely than your assumption that soil animal welfare dominates, and I suspect that even those who know much more than me about this should be much less precise in their estimates.

Importantly, I still agree with the main takeaway that we need more research on soil animal welfare (although it might end up not being a crux for me, given the above---I think red-teaming the various assumptions various people make about inter-species tradeoffs should also be a priority.).

Vasco Grilo🔸

7mo

Thanks for the comment, Jim!

0.0374 % is my best guess, but I agree there is lots of uncertainty. For an exponent of the number of neurons of 0.188, which explains pretty well the welfare ranges in Bob's book about comparing animal welfare across species, the effects on soil animals would dominate even more easily. However, I would also not be surprised if 100 times as much consumption of the affected farmed shrimp, 3.74 % (= 100*3.74*10^-4), would have to be replaced by farmed fish for effects on soil animals to dominate, in which case I could easily electrically stunning shrimp increasing animal welfare.

My main takeaway from the section where I discuss eletrically stunning shrimp is that I do not really know whether it increases or decreases welfare. I would still believe this even if my preferred way of comparing welfare across species was certain to be right. There is plenty of uncertainty in whether electrically stunning farmed shrimps increases or decreases the welfare of soil animals, and in the replacement of the consumption of farmed shrimps by other foods.

I agree decreasing the uncertainty about comparing welfare across different potential beings should also be a priority. I just feel it is very hard to make progress on this in comparison to gaining a better understanding of the conditions of soil animals in different biomes.

Jim Buhler

7mo*

My main takeaway from the section where I discuss eletrically stunning shrimp is that I do not really know whether it increases or decreases welfare. I would still believe this even if my preferred way of comparing welfare across species was certain to be right. There is plenty of uncertainty in whether electrically stunning farmed shrimps increases or decreases the welfare of soil animals, and in the replacement of the consumption of farmed shrimps by other foods.

Yup, agreed species tradeoffs are not the only source of deep uncertainty.

I agree decreasing the uncertainty about comparing welfare across different potential beings should also be a priority. I just feel it is very hard to make progress on this in comparison to gaining a better understanding of the conditions of soil animals in different biomes.

To be clear, to me, "making progress" may mean realizing that we should be and (tentatively?) remain deeply uncertain about inter-species tradeoffs^[1] and hence prioritize interventions that are most likely good independently of (non-obvious) tradeoffs assumptions (e.g., interventions that are ecologically inert and avoid substitution effects, or close to that). I could imagine myself reaching such a conclusion quite quickly after diving into the literature on inter-species tradeoffs.^[2]

^{^}
Much more than what the moral weight project suggests us to be.
^{^}
For instance, I wouldn't be surprised if I find out that anyone's precise-ish moral weights inevitably depend on way-too-strong assumptions about the nature of consciousness and how the importance of suffering scales with its severity.

Vasco Grilo🔸

7mo

To be clear, to me, "making progress" may mean realizing that we should be and (tentatively?) remain deeply uncertain about inter-species tradeoffs^[1] and hence prioritize interventions that are most likely good independently of (non-obvious) tradeoffs assumptions (e.g., interventions that are ecologically inert and avoid substitution effects, or close to that).

I am very pessimistic about finding interventions that robustly increase welfare in expectation in my view across all reasonably plausible ways of comparing welfare across individuals. In addition, I would be surprised if such interventions were the ones increasing welfare the most cost-effectively.

Jim Buhler

7mo

I partly share your pessimism. I hope we'll have occasions to discuss specific proposals soon!

I would be surprised if such interventions were the ones increasing welfare the most cost-effectively.

If you define cost-effectiveness as something close to "what's best in expectation according to my specific favorite among all the plausible ways of comparing welfare across individuals", I agree. I would also be surprised. I'm just---as you probably have realized---very sympathetic to Anthony and Mal's arguments (in the above-linked posts) that this is not what we should look for when we seek cost-effectiveness.

I saw you already discussed this and adjacent cruxes with them. I might write something relevant to this (precise vs imprecise beliefs, etc.) in the very context of moral weights at some point. I'll reach back to you then, and maybe we'll be able to hit finer-grained cruxes and advance this discussion. :)

Vasco Grilo🔸

7mo

If you define cost-effectiveness as something close to "what's best in expectation according to my specific favorite among all the plausible ways of comparing welfare across individuals", I agree.

Yes, that is how I was thinking about it, with the caveat that the specific favourite would involve weighting many ways of comparing welfare by their plausibility, at least implicitly.

I saw you already discussed this and adjacent cruxes with them. I might write something relevant to this (precise vs imprecise beliefs, etc.) in the very context of moral weights at some point. I'll reach back to you then, and maybe we'll be able to hit finer-grained cruxes and advance this discussion. :)

Thanks for letting me know!

Vasco Grilo🔸

5mo

I [Jim] think maybe we should be more uncertain about inter-species tradeoffs than you seem to be, here.

I agree I have underestimated the uncertainty in comparisons between the individual (expected hedonistic) welfare per unit time of different species. I now recommend decreasing this uncertainty.

Jim Buhler

5mo

Interesting, thanks for the update!

Vasco Grilo🔸

7mo

Here is a discussion related to this post with Bob Fischer and Mal Graham, who "make most of the strategic and granting decisions for Arthropoda [Arthropoda Foundation]".

Vasco Grilo🔸

5mo

I recommend research informing how to increase the welfare of soil animals over pursuing whatever land use change interventions naively seem to achieve that the most cost-effectively.

I currently recommend decreasing the uncertainty about how the (expected hedonistic) welfare per unit time of different organisms and digital systems compares with that of humans. I am now more pessimistic about the above. I have very little idea about whether existing interventions which robustly increase the welfare of humans or non-soil animals increase or decrease animal welfare due to potentially dominant uncertain effects on soil animals. Likewise, I do not know whether hypothetical interventions which robustly increased the welfare of soil animals would increase or decrease welfare due to potentially dominant uncertain effects on soil microorganisms.

Tristan Katz

5mo

Sorry I'm late to comment here, and I'm aware you've written a lot on this topic. But I think this post would benefit from an explanation as to why you're using neuron counts as a proxy for the importance of the animal's welfare.

As far as I'm aware, neuron count is not considered to be a good proxy or indicator of sentience, nor does it seem to be a good proxy for the intensity of experience (I'm not even aware of any good reason for assuming a difference in welfare range between sentient species, although I'm aware that this position is commonly held). Regarding the simple question of whether they're sentient, wouldn't it make more sense to base this on current evidence for sentience, or reasonable assumptions about what evidence future sentience research might produce, given the characteristics of these species?

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shloka 🔸

7mo*

Hi Vasco! I was wondering if you've thought about the effects of land use change on soil nematodes at finer taxonomic resolutions. I think this could be relevant for the following reasons:

There is some variation in neuron counts between nematode species. For example, Mermis negrescens is a grasshopper parasite that has ~1,000 neurons in its ventral nerve cord.
Even though most soil nematodes have similar simple nervous systems, there is significant variation in their life history strategies. The equivalent of r vs K-selected life histories for nematodes is the colonizer-persister scale from 1 to 5. On the lower extreme, colonizers (roughly comparable to r-strategists) have high reproduction rates and experience large fluctuations in population density under uncertain environmental conditions. The Rhabditid family of nematodes, which includes C. elegans, is one such example. On the higher extreme, persisters (roughly comparable to K-strategists) have low reproduction rates and maintain population size in more stable conditions. The Thornematidae and Nygolaimidae families are examples of persisters. Of course, many nematode families fall somewhere in the middle. The colonizer-persister scale also probably obscures other important differences between nematode species, like variation in lifespan. I'm wondering if all this variation suggests that all soil nematodes shouldn't be thought of as a single group in such welfare analyses because some might have much lower welfare than others.
Soil nematodes also have ecologically diverse roles: plant parasites, predators, animal parasites, and bacterial/fungal feeders. Land use change will probably differentially impact these functional groups (as well as colonizers vs. persisters). For example, this study suggests that intensively managed land might produce disturbance regimes that select for colonizers, who probably have worse lives than persisters. And here's another study that observed decreased predator nematodes population abundances after urbanization, which might be bad if predators have particularly good lives. If these studies are right, it seems really important to take local selective conditions into account to avoid land use changes that cause harm.

Thanks for your post, and I apologize if you've addressed this elsewhere!

^{^}

Much more than what the moral weight project suggests us to be.

^{^}

For instance, I wouldn't be surprised if I find out that anyone's precise-ish moral weights inevitably depend on way-too-strong assumptions about the nature of consciousness and how the importance of suffering scales with its severity.

Prioritise soil animals over farmed invertebrates?

Prioritise soil animals over farmed invertebrates?

Summary

The total welfare of soil animals is much larger in absolute terms

Projects targeting soil animals receive way less funding

Interventions changing land use can increase welfare much more cost-effectively than ones targeting farmed invertebrates

I recommend research informing how to increase the welfare of soil animals

There is no escape from the uncertainty of the effects on soil animals

Interested in funding research informing how to increase the welfare of soil animals?

Acknowledgements