Summary

• I Fermi-estimated the scale of the welfare of various animal populations from the relative intensity of their experiences, moral weight, and population size.
• Based on my results, I would be very surprised if the scale of the welfare of:
  • Wild animals ended up being smaller than that of farmed animals.
  • Farmed animals turned out to be smaller than that of humans.

Introduction

If it is worth doing, it is worth doing with made-up statistics?

Methods

I Fermi-estimated the scale of the welfare of various animal populations from the absolute value of the expected total hedonistic utility (ETHU). I computed this from the product between:

• Intensity of the mean experience as a fraction of that of the worst possible experience.
• Mean moral weight.
• Population size.

The data and calculations are here.

Intensity of experience

I defined the intensity of the mean experience as a fraction of that of the worst possible experience based on the types of pain defined by the Welfare Footprint Project (WFP) here (search for “definitions”). I assumed:

• The following correspondence between the various types of pain (I encourage you to check this post from algekalipso, and this from Ren Springlea to get a sense of why I think the intensity can vary so much):
  • Excruciating pain, which I consider the worst possible experience, is 1 k times as bad as disabling pain.
  • Disabling pain is 100 times as bad as hurtful pain, which together with the above implies excruciating pain being 100 k times as bad as hurtful pain.
  • Hurtful pain is 10 times as bad as annoying pain, which together with the above implies excruciating pain being 1 M times as bad as annoying pain.
• The intensity of the mean experience of:
  • Farmed animal populations is as high as that of broiler chickens in reformed scenarios. I assessed this from the time broilers experience each type of pain according to these data from WFP (search for “pain-tracks”), and supposing:
    • The rest of their time is neutral.
    • Their lifespan is 42 days, in agreement with section “Conventional and Reformed Scenarios” of Chapter 1 of Quantifying pain in broiler chickens by Cynthia Schuck-Paim and Wladimir Alonso.
  • Humans and other non-farmed animal populations is as high as 2/3 of that of hurtful pain. 2/3 (= 16/24) such that 1 day (24 h) of such intensity is equivalent to 16 h spent in hurtful pain plus 8 h in neutral sleeping.

Ideally, I would have used empirical data for the animal populations besides farmed chickens too. However, I do not think they are readily available, so I had to make some assumptions.

In general, I believe the sign of the mean experience is:

• For farmed animal populations, negative, judging from the research of WFP on chickens.
• For humans, positive (see here).
• For other non-farmed animal populations, positive or negative (see this preprint from Heather Browning and Walter Weit).

Moral weight

I defined the mean moral weight from Rethink Priorities’ median estimates for mature individuals^[1] provided here by Bob Fischer^[2]. For the populations I studied with animals of different species, I used those of:

• For wild mammals, pigs.
• For farmed fish, salmon.
• For wild fish, salmon.
• For farmed insects, silkworms.
• For wild terrestrial arthropods, silkworms.
• For farmed crayfish, crabs and lobsters, mean between crayfish and crabs.
• For farmed shrimps and prawns, shrimps.
• For wild marine arthropods, silkworms.
• For nematodes, silkworms multiplied by 0.1.

Population size

I defined the population size from:

• For humans, these data from Our World in Data (OWID) (for 2021).
• For wild mammals, the mean of the lower and upper bounds provided in section 3.1.5.2 of Carlier 2020.
• For farmed chickens and pigs, these data from OWID (for 2014).
• For farmed fish, the midpoint estimate of this analysis from Kelly Anthis and Jacy Anthis (for 2019).
• For wild fish, the mean between the mean of the lower and upper bounds provided in section 3.1.5.5 of Carlier 2020, and the order of magnitude given in Table S1 of Barn-On 2018.
• For farmed insects raised for food and feed, the mean of the lower and upper bounds provided here by Abraham Rowe (in the 2nd point of the section “Key Findings”).
• For farmed crayfish, crabs and lobsters, and farmed shrimps and prawns, the ratio between the means of the lower and upper bounds for:
• The number of individuals killed per year provided here by fishcount.org (for 2017).
• The time in years farmed shrimps spend in grow-out ponds, developing from juvenile until market size, according to this Wikipedia page.
• For wild terrestrial and marine arthropods, and nematodes, the orders of magnitude from Table S1 of Barn-On 2018.

Results

The results are presented in the table below by descending absolute value of ETHU as a fraction of that of humans, i.e. decreasing scale of welfare.

Discussion

According to my results:

• The intensity of the mean experience of farmed chickens, estimated from data for broilers in reformed scenarios, is 2.93 (= 19.6/6.67) times as high as that of humans. Intuitively, I would guess the ratio to be higher, but I believe I am biassed towards overweighting the time in disabling and excruciating pain. This is indeed super bad, but does not last for long.
• Wild animal welfare dominates. Among the 12 populations I analysed, the 5 whose welfare has the largest scale respect wild animals, and the 7 lowest scale farmed animals and humans. This did not surprise me given the sheer numbers of wild animals.
• The order of the scale of welfare among wild animals roughly matches what I estimated here based on the total number of neurons, with arthropods and nematodes being the major drivers. The welfare of nematodes has a greater scale here, but my guess for the moral weight of nematodes has quite low resilience.
• Among the populations of farmed animals and humans, the welfare of insects raised for food and feed has the lowest scale. I actually expected it to be larger, but I think I was overestimating their population size.
• There is a meat-eater problem. The combined importance of the 4 populations of farmed animals I analysed is 18.1 (= 1.78 + 2.31 + 2.64 + 11.3) times as large as that of humans. Consequently, a smaller human population will tend to increase welfare in the nearterm if we ignore the effects on wild animals. However, these dominate, and can be positive or negative, so I have no idea what is the overall nearterm effect of changing the size of the human population. For similar reasons, I think it is very hard to say whether GiveWell’s top charities are beneficial or harmful.

The specific ordering of the various animal populations by scale of welfare I got is not robust given the high uncertainty of my results. However, I would be very surprised if the scale of the welfare of:

• Wild animals ended up being smaller than that of farmed animals.
• Farmed animals turned out to be smaller than that of humans.

I would say any scope-sensitive ethic will lead to these conclusions, not just expectational total hedonistic utilitarianism.

1. ^{^}

    This post from Bob Fischer looks into the moral weight of juvenile insects.

2. ^{^}

    Bob Fischer shared the means here, but recommended using the medians.