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Related: Assessing biomarkers of ageing as measures of cumulative animal welfare

Several people have asked me how they or others can take the ideas from my previous post on ageing-based measures of animal welfare forward and apply them to helping animals. Since I've now left WAI and won't be working on this further, I thought I'd draw a line under my involvement by quickly sketching out some ways I can see further work on this being valuable. This is not an organised research agenda; rather, it is a relatively unprioritised and informal list of things I would like to see happen in this space.

I would expect useful future work on ageing-based welfare measures (henceforth AWMs) to fall into four broad categories:

  1. Further development of biological ageing measures that are suitable for use as AWMs
  2. Theoretical or experimental work investigating the scope and limitations of AWMs
  3. Applying AWMs to investigating active uncertainties in animal welfare
  4. Outreach to spread awareness of AWMs among groups that could make use of them or develop them further

I’ll address each of these separately, but I expect many projects could attack two or more of these categories simultaneously.

1. Development of new ageing measures in animals

What is it?

There are many different ways of measuring biological age. Of these, telomere length seems to be by far the most widely used in nonhuman animals. As far as I know, telomere length and hippocampal volume (which I know much less about) are the only ageing metrics that have been applied specifically as measures of cumulative welfare.

I expect that other measures of biological ageing may turn out to be at least as useful as telomere length, and possibly more so in contexts where telomere length performs relatively poorly. It would therefore be good to see more work done to evaluate other biomarkers of ageing as potential welfare measures (in terms of comprehensiveness, cost, transferability, etc.), and to develop new, better ways of combining different biomarkers into effective composite measures.

One reason I think it would be particularly valuable for people with a specific interest in animal welfare to work in this space is because they will have different priorities from researchers whose primary goal is advancing human biomedical science. In particular, they will place greater weight on the cost and transferability of potential AWMs, as these will be of particular importance in funding-constrained animal contexts. Hence, state-of-the-art AWMs may well differ substantially from the methods that are currently best regarded in the ageing field.

Why is it valuable?

  • I expect different biomarkers of ageing to have different pros and cons as measures of welfare. Further exploration of this space could uncover biomarkers that are complementary or superior to telomere length in this context.
  • Better methods of combining biomarkers could allow researchers to obtain better measures of biological age at lower costs.
  • Better understanding of the cost and transferability of these measures would help welfare scientists and organisations better select which measures they want to use in their species of interest, lowering the cost of entry to using these methods.
  • Discovery and validation of new ageing-based welfare measures would help to validate the approach as a whole and encourage its use in more species and contexts.

Who could do it?

A lot of the work in this area probably requires access to biological laboratory facilities and so would be restricted to researchers with that access, primarily academics. Nevertheless, initial work to identify promising biomarkers could be done through literature reviews and other approaches that do not require access to labs, and I expect development of new composite measures to benefit from data-science and machine-learning skills that are rare in traditional biological research groups, so there is definitely scope for others to contribute here as well.

2. Exploring the ageing-welfare connection

What is it?

The idea of measuring cumulative welfare using biological ageing is new, and the literature on the topic is small. It is still unclear exactly how broad the scope of these methods is or which approaches to measuring ageing for welfare are most promising. There is therefore broad scope for both theoretical and empirical research to provide valuable information on the potential of AWMs in general.

Some questions I would like to see addressed in the future include:

  • Can the theoretical argument for the ageing-welfare connection be developed into something more formalised (and therefore potentially more testable)?
  • Can the theoretical argument be extended to convincingly cover social stresses (footnote 15 in the original report)?
  • Is it possible to adapt ageing-based welfare methods to apply between groups that differ in genetic composition, such as different strains of boiler hens?
  • Several people, including me, have worried that these methods might underweight the importance of rare acute events. Is there a way to work out if these worries are well-founded?
  • What methods might be best for measuring the cumulative welfare of juveniles versus adults?
  • How might ageing-based welfare methods be applied in insects or other invertebrates? How might we go about validating these applications?
  • Can ageing-based welfare methods be applied to animals with unusual ageing trajectories?
  • How well do ageing-based methods incorporate positive experiences? Is it even theoretically possible to address this question?

Which of these questions is of highest priority depends on one's focus; the validity of AWMs in invertebrates and animals with unusual ageing trajectories is much more important for those interested in wild-animal welfare, for example, while issues of genetic composition will be especially important for those interested in comparing the welfare of different domesticated strains.

Why is it valuable?

  • Answering these questions would help give us a much better idea of the scope of AWMs in general: when they do and don’t apply and when they might be better or worse than alternative methods. This would help researchers and activists make more informed choices about when to use them.
  • Work on these issues could also help clarify what productive approaches to the other two areas of research discussed here (developing new measures and applying them in practice) are likely to be.

Who could do it?

Some of these questions could be best addressed by a theoretical analysis or literature review, while others would require novel biological experiments or a combination of different approaches. Individual researchers in an academic context, such as Masters students, would be well-placed to address many of these questions. Animal-focused EA researchers could also likely make headway in this space if they are analytically minded and have (or can acquire) a reasonable grounding in evolutionary biology.

3. Applying AWMs to welfare questions

What is it?

It would be good to start seeing applications of existing ageing-based welfare measures to uncertainties in animal welfare. WAI is in the process of developing projects that apply these techniques to wild-animal welfare, but I expect many of the most valuable early applications to relate to the welfare of captive animal populations.

Some key uncertainties I am aware of in this space include the relative welfare of caged versus cage-free chickens, the value of different approaches to improving the lives of farmed fish, and the relative welfare impacts of different forms of tagging and sampling in farmed and laboratory populations. I am sure people more actively involved in the animal-welfare movement would be aware of others.

The design of these experiments could be quite simple. Many could simply follow the template I set out in the original post: get two or more groups of animals living under different conditions, measure the biological age of individuals of different chronological ages, and plot the biological ageing curve for each population.

Why is it valuable?

  • The purpose of developing new welfare measures is to let us better assess the welfare conditions of animals, so applying ageing-based methods in this way is directly valuable to the cause of animal welfare.
  • Actually doing studies using these methods would help take them from the realm of theory into actual practical usefulness, and so perhaps attract more attention and capacity from other welfare scientists and welfare organisations.
  • It is difficult to predict how a method will fare in practice until it has actually been tried. Organising these experiments would generate important practical knowledge that could then be shared with other interested parties.

Who could do it?

Performing these experiments would require a mixture of skills including animal handling, molecular biology and statistical analysis, as well as access to animal populations of interest and suitable laboratory facilities. Active collaborations with co-operative farms (or other animal facilities) and academic groups with the requisite expertise are likely to be critical.

Though I expect relatively few animal welfare organisations will have the necessary laboratory expertise or facilities to perform these experiments in-house, I can certainly envision a nonprofit organisation with an empirical focus and in-house data-analysis skills partnering with academic or industry collaborators to perform this work.

4. Spreading awareness of AWMs

What is it?

Currently, the the general level of awareness around AWMs is very low. I'm aware of a very small number of academics (and one nonprofit, WAI) doing research explicitly in this area, and a small number of other organisations have expressed tentative interest. This is a precarious situation; given this level of awareness, it would not be too surprising if these methods fail to be taken up and used widely in future.

High-quality outreach about these methods, which explains why they are potentially so valuable and how they could be of use to welfare scientists and organisations, therefore has the potential to be highly impactful, especially if further research suggests AWMs will live up to their current promise. This is what I am trying to do with these posts, and it is my hope that the word will spread further.

Why is it valuable?

  • The more researchers, organisations and funders are aware of the potential of AWMs, the more likely it is that further exploration and application of these methods will be funded and performed.

Who could do it?

This may be an area where EA-aligned animal-welfare organisations could be particularly impactful, as they already have experience with outreach and connections with other organisations who could potentially make great use out of AWMs. Funding bodies interested in this area could also have an impact by specifically advertising their interest in proposals to advance this area (or other promising new methods for measuring welfare), therefore simultaneously raising awareness and creating the opportunity for further progress to be made.

What can a generalist do?

EA is long on generalist researchers and short on biologists. Many of the promising directions I've discussed here require access to a laboratory, or at least to biological expertise. However, there are several topics I think could benefit from immediate attention from animal-focused generalist researchers and organisations.

Firstly, as a researcher at WAI, my thinking about AWMs has been focused on their applications to wild-animal welfare. While I have discussed some examples of where I think these methods could be applied to domesticated animals, a more thorough review by someone with more knowledge of that area could be valuable, both to attract attention to the topic in that space and to help target future resources more effectively.

Secondly, given some reading up on evolutionary biology and comparative psychology, I think progress could be made on many of the questions in section 2 without access to a laboratory, both through focused literature reviews and greater theoretical scrutiny. A better idea of the strength and scope of the theoretical underpinnings of AWMs would be very valuable for directing research in the future. Topics I think could especially benefit from this include ageing in juveniles, the welfare-measurement potential of ageing biomarkers in insects and other invertebrates, and whether or not it is possible to use these methods to assess the welfare effects of genetic differences between groups. Progress could probably also be made on the relative potential of different currently-existing ageing metrics for use as AWMs in animals.

Finally, many animal-focused EA orgs have strong connections with other animal-welfare organisations, researchers and funders. Actively spreading the word about the potential of AWMs within their network represents one of best routes I can see to achieving more general awareness of, and investigation into, these promising new methods.





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Strong upvote, since I think it is highly important to publish these kind of follow-up research questions or research agendas. Both to improve coordination/discussion and to offer more options for people who are interested in doing EA research. I also liked that there is a section on what generalists can do.

This seems like a promising approach to comparing hedonic wellbeing across species of nonhuman animals. Comparing human with nonhuman wellbeing is also important for prioritising interventions, and there doesn't seem to be a good way of doing this at the moment. Do you think this could be part of a solution?

Sadly AWMs only really give a relative measure of welfare against a comparable genetic background: you can use them to say population A is ageing faster than population B and therefore has worse cumulative welfare, but not (at least currently) to obtain an absolute welfare measure for either population. That makes it difficult to see how they could be used to compare welfare between different species, including humans.

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