The challenges of comparing welfare across species

Hayana Fernanda/Pexels.

Source: Hayana Fernanda/Pexels.

Comparing animal welfare across species is fraught with conceptual and empirical challenges.1 However, we know that some progress has been made because we have learned how to identify the major differences in the emotional life of individuals of the same species.

When we try to scale animal welfare across species, questions like these arise: Can humans suffer more than other animals? Are our pains worse? And if so, how much worse are they? Is the most intense pain for a human ten times worse than the most intense pain for a chicken? A thousand times worse? Even more terrible? These are the puzzles that Bob Fischer and his team pack in Weighing animal welfare: comparing welfare between specieswhich has just been published open access by Oxford University Press. It is available for free here.

To accomplish this daunting task of scaling prosperity, Fischer, a senior researcher, has contributed Reconsider priorities and professor at Texas State University, assembled a diverse team to work on these questions about pain intensity in the animal kingdom. The contributions include comparative data cognition experts, animal welfare scientists, neuroscientists and philosophers. Together they developed a method that allowed them to outline some preliminary answers.

Marc Bekoff: What are the most important results of your research?

Bob Fischer: The result of Animal welfare weighing is that while there are probably differences between humans and other animals, they are not huge differences. For example, we estimate that a pig’s pain may be about half as intense as a human’s, and a chicken’s pain slightly less. Put another way, we think the best evidence supports the view that animals’ experiential peaks and valleys are relatively similar and vary based on their cognitive abilities.

Oxford University Press/with permission.

Source: Oxford University Press/with permission.

If we are on the margins of the truth, that means that pigs and chickens can suffer a lot! Imagine, if you can, that suffering is half as intense as the worst suffering you have ever experienced. That would still be a horrible experience. So if we have good reasons to prevent that kind of suffering in humans, then we also have good reasons to prevent it in these animals.

MB: How did you generate these estimates?

Friend: There is no direct way to measure the intensity of pain between species. There is no neurological measure that makes the process simple. Likewise, many indirect methods are not useful. For example, we cannot use behavioral evidence, such as how hard animals will work to avoid pain. All animals do everything they can to avoid the worst experiences, so the only thing we would learn from that method is how to compare pains within species. So we had to get creative.

Our strategy involved looking at the many functions of states that feel good and bad to animals – scientists call them “valentive states.” Valenced states do many things for animals: they convey information about threats and opportunities, they help animals learn, they motivate action, and they help animals make trade-offs. By comparing how well animals can perform these functions – that is, how much information they can represent, how much and how well animals can learn, etc. – we can begin to understand the possible differences in their valence states. In Figure 1 you can see some of the features we considered.

Source: Bob Fischer/with permission.

Properties relevant to the functions of the valence states of six animals: pigs, chickens, salmon, octopuses, shrimp and flies.

Source: Bob Fischer/with permission.

Once we had a picture of animals’ capabilities, we built a model to synthesize this information into a single estimate of the “welfare range” per species, which is a way of representing how intense their experiences can be.

Of course, there were many complications along the way. And if comparing pain between species weren’t so important, this project might not be worth pursuing. But people constantly make trade-offs involving animals that are based, at least in part, on assumptions about what animals feel. So it is important to try to compare the intensity of animals’ pain.

MB: Did you just study pain?

Friend: No, we looked at animals’ capacities for both positive and negative experiences. However, because pain is easier to study than positive experiences, many of the studies we reviewed focused on pain. And while the negative focus is unfortunate, pain is a useful test case, as it is probably one of the most intense negative experiences animals can have (compared to e.g. boredom or tensionboth of which are negative, but usually not as acute as intense pain). Moreover, insofar as we consider it especially important from a moral point of view to relieve pain, it is good to spend a lot of time thinking specifically about pain.

MB: What do you hope your work will achieve?

Friend: We try to make two main contributions. The first is to start a conversation about the best way to make these comparisons. We know we haven’t said the last word – or anything close to it! However, research has to start somewhere. By taking a first stab at this project, we hope that others will point out the limitations of what we have done, suggest ways to do it better, and then continue the work themselves. We would like to see a flourishing field of research examining whether and when the stakes are higher for a chicken than for a pig – or for a human.

The second contribution is to provide some first-pass, proof-of-concept results. People might have thought that if anyone ever tried to quantify the differences in pain intensity between animals, the research would show that we can virtually ignore the negative experiences of some animals, such as invertebrates. From this view, if shrimp feel anything at all, it barely registers on the scale. But our work suggests otherwise. Yes, there are probably differences between species. However, we do not think the evidence supports the view that the pain experienced by these animals is completely trivial. We must treat those animals in a way that takes their capabilities into account.