Shriver presents two example proposals for what might be done. First, we might
create knockouts of other mammals (cows and pigs for starters) lacking the AC1 and AC8 enzymes. Interfering with the cAMP cycle in the brain reduces the affective dimension of chronic or persistent pain, rather than pain full stop, but this would still be an improvement over current circumstances. If we could eliminate the sensitization that occurs as a result of painful or traumatic experiences, the animals would still be better off than they are now.Secondly,
Zhou-Feng Chen and colleagues searched the Allen Brain Atlas to find genes that were highly expressed in the ACC but not other areas of the brain . One strong candidate was the peptide P311. The researchers created knockout mice lacking the expression of P311 and found that heat and mechanical sensitivity were normal in the animals. However, they then performed a conditioned place aversion test on the animals and found that the knockouts no longer demonstrated the conditioned place aversion caused by formalin injections, in stark contrast to control rats. Thus, at first glance, it appears that knocking out P311 in mice strongly diminishes the affective dimension of pain while keeping acute responses intact.Since I'm even more interested in wild-animal suffering than farm-animal suffering, in view of the vast difference in numbers of animals involved, my immediate question was whether similar techniques might one day be applicable there. Doing so is a lot trickier, because evolution produced the badness of pain for a reason. Shriver mentions this concern:
Furthermore, P311 is likely to play a similar role in all mammals (Chen, personal communication), so one presumably could engineer other mammals that have a reduced affective dimension of pain while maintaining the sensory dimension of pain.
Since it seems likely that the affective dimension of pain played some role in determining the evolutionary fitness of organisms, we might question whether knockout livestock could really survive up through the point where they are normally slaughtered. However, it appears that the experimental rats were able to survive without complication at least in their cages (Chen, personal communication). This would be a good model for sows or veal calves who spend most of their lives confined in small pens where they can’t do much of anything that would injure or otherwise harm themselves.Producing genetically fit wildlife without pain might require not just knocking out pain but replacing the "pain" - "pleasure" axis with a "less pleasure" - "more pleasure" axis, which could be much more difficult.
I mentioned that Shriver's proposal seems obviously valuable from my perspective, but unfortunately this isn't necessarily the case among the general public. As the New Scientist article notes:
[Alan] Goldberg also contends that public attitudes may make pain-free livestock a non-starter. He and colleague Renee Gardner conducted an online survey on the use of pain-free animals in research and found little public support, even among researchers who experiment on animals (Alternatives to Animal Testing and Experimentation, vol 14, p 145).This underscores the importance of public outreach to change hearts and minds about wild-animal suffering and how it could be prevented.