Knocking Out Pain in Livestock

Hi, thanks very much to Gualtiero for allowing me to post here.  Last summer, I published an article in the journal Neuroethics discussing the possibility of genetically engineering livestock that lack the affective or “suffering” component of pain.  New Scientist magazine picked up on the story and this generated a little flurry of media activity.  It was fun getting a lot of feedback on the paper, but as you might imagine, much of the discussion revolved around people’s pretheoretical intuitions on the subject, so I’ve been looking forward to the possibility of getting some feedback from the Philosophy of Brains community.

Anyway, the basic idea of the article (which can be found here) is as follows: I think the question “Will we be able to get rid of intensive factory farming in the near future?” is an empirical question.  It’s a complicated empirical question since it ultimately depends upon many people’s ethical decisions, but nevertheless there are ways of evaluating whether it is a realistic possibility.  Based on the evidence I’ve seen, I’d say it’s extremely unlikely that our society will change our habits enough in the near future to eliminate the practice of factory farming.  Given this, and since factory farming is responsible for a huge amount of suffering, I argue that we ought to genetically engineering animals that lack the ability to feel pain (or rather, the ability to feel a particular component of pain).

Furthermore, I think we’re actually very close to being able to do so.  In order to say why, I need to briefly review some facts about the pain system in mammals.  Scientists have identified two distinct pathways from nociceptors to higher brain regions.  The sensory pathway (which travels from the thalamus to the primary and secondary somatosensory cortex) underlies our ability to localize pain, to estimate it’s intensity, and to describe what type of a pain it is (sharp, dull, burning, etc).  The affective pathway (which travels from the thalamus to the anterior cingulate cortex and the insula) underlies subjects’ judgments of how unpleasant the pains are, or how much the pains are minded.  Humans who have damaged affective pathways (particularly the anterior cingulate) will report that they still feel pain but no longer mind it.  As such, lesioning the anterior cingulate (ACC) is used in rare cases to treat debilitating chronic pain.  The role of the ACC in human pain has been further verified by fMRI studies, single-unit recordings (yes, in humans), and pharmacological interventions.

In nonhuman mammals, a similar pattern of results is observed.  Rats with damage to the ACC will still show immediate reactions to noxious stimuli, but will no longer change their preferences as a result of this stimulation.  Morphine, which disproportionately acts on the affective pathway in the brain, causes similar effects.  Furthermore, increasing neural activation in the ACC will cause rats to avoid certain environments even in the absence of noxious stimulation, while blocking ACC activity will prevent rats from avoiding these environments even in the presence of noxious stimulation.  Thus, I argued in a previous paper, it appears that the ACC plays a similar role in pain perception in other mammals as it does in humans.

But what’s really interesting, from my perspective, is that researchers have been learning a huge amount about the cellular neurobiology of the ACC in recent years.  Min Zhuo’s lab at Toronto has identified neurons in cortical layers II/III of the ACC that  change their synaptic connections as a result of painful stimulation.  Blocking long-term potentiation in these neurons results in rats that show the immediate reaction to painful stimulation but lack the symptoms of chronic pain found in controls.  In fact, the lab has performed several genetic knockouts on the rats that appear to selectively block the affective dimension of pain.

More research needs to be done, but given that scientists appear to be able to locate specific genes that influence the affective dimension of pain, it looks to me that creating pain affect knockouts in other mammals, such as those that are used as livestock, would not be an especially difficult endeavor.  We already know what genes to look for, and have a good idea of what kinds of tests could be used to look for similar effects.  Thus, I argue, we are very close to being able to create livestock that can still have an immediate reaction to pain while lacking the unpleasant sensation that seems to constitute the suffering of pain.

If we are able to do this, and if there’s no indication that we will be getting rid of factory farming in the near future, shouldn’t we take steps to mitigate the suffering of millions of animals every year?


  1. In theory a cool idea, in practice not so sure.

    I worry it will bring out sadism in employees at the farms. “Hey, Fred look I can stick a needle in this thing’s leg and it doesn’t give a crap!” My hunch is that cries of pain from the animals act as a conscience pin, and taking this away could be bad.

    Also, people will be skeptical of eating such meat. OTOH, it could become a specialty item for hippies, much like “organically raised” livestock (most likely scenario). Alternatively, if enough mass producers used it, people would have no choice but to eat it. This scenario is unlikely as such cattle would be very expensive to produce.

  2. shannon

    hi adam. this is an interesting topic. thanks for bringing it to Brains.

    suppose you’re right that we could genetically modify animals so that they lack the unpleasant sensation that bodily harm usually causes. that doesn’t seem to solve the ethical or the non-ethical problems with factory farming. animals in factory farms still have basic interests that are violated. and there are several health and environmental issues with factory farms. factory farms are bad news for many reasons. the animals’ pain and suffering may not even be the worst problem.

    none of that is news to you, i’m sure. but here’s a question for you. what if the best shot of getting rid of factory farming involves showing the horribly painful lives of factory-farmed animals? what if pulling at the heart strings of meat-eaters by showing them PETA-like videos of the suffering animals endure is the best way to solve the ethical and non-ethical problems?

    judging from my students’ reaction to this topic, the reasoned arguments fade away when it’s dinner time. it’s the appeal to emotion that sticks.

  3. Adam

    Eric, thanks for the comments. Some thoughts on the issues you raise:

    1. I agree that this could increase the risk of sadism, or something like sadism. Unfortunately, from reports I’ve hard, many of the meat processing plants are already rather dehumanizing and the animals are already treated very poorly (for example, in Texas, I had a neighbor who used to work in a chicken plant and said that workers often played “football” with live chickens). But I agree it’s possible that this could increase the risk of even worse activity, or of the people in charge of preventing such activity being more lax. On the other hand, since this would selectively knockout the affective pathway, but leave the sensory pathway intact, my guess is that the animals might have a very similar immediate reaction to painful stimulation, so the loss of an empathy-triggering reaction might not occur. I think the risk of worse treatment of animals would come primarily from the fact that the employees believe that the animals aren’t suffering.

    2. I actually don’t think this would be expensive to implement after the original research was done. The animals would be genetically modified, so once the changes are made they could be bred in the same way they are now, with the modifications preserved across generations. But I agree that creating a “hippie market” might be a good way to get the idea going (provided, of course, that there is sufficient evidence that the animals are actually suffering less).

    3.From the reactions I’ve seen in other places, I’m sure you’re right that people would be initially resistant this idea. However, there was an interesting study done at Johns Hopkins asking about using “pain-free” animals in research. Interestingly, a majority of people polled thought that it would be wrong to genetically engineer animals to not feel pain for the sake of scientific research. However, people also thought that *if* you already had animals that had been genetically modified in this way, then you had a moral obligation to use those animals instead of nomal animals that can feel pain. So, I feel like there’s a little bit of the emotional dog wagging the rational tail phenomenon going on based on an initial repulsion to the idea of GE, and I hope that people might be more open to such ideas after they’ve had more of a chance to think about them.

  4. Adam

    Shannon, thanks for the kind words and comment.

    I agree that there are many problems with factory farming, and that the ideal solution is to get rid of the practice altogether. And I would say from personal experience that most of the people I know who are vegetarian for ethical reasons are not focused on only one reason (say, animal suffering), but generally list a whole range of ethical concerns with the factory farming industry. So I definitely agree that this solution is not optimal, and that even if it were implemented there would still be good reasons to continue to advocate for the elimination of factory farms.

    But you seem to be saying something further. Given that there are other (arguably more important) problems with factory farming, one could argue that eliminating pain-related suffering is a bad thing because it would prevent us from making these further changes. This is an interesting idea and I have several different things to say about it:

    1. This suggestion seems to depend on the idea that showing videos of animals in pain can be successful in convincing people to stop eating meat. I definitely agree that pulling the heart strings can be effective (and, for some people, is more effective than philosophical arguments) in getting people to change their eating habits. However, the limited success of this is counteracted by the strong influence of culture and tradition, as well as the multibillion dollar agribusiness industry that pays people lots of money to think about how to convince people to eat more meat. So I don’t see any great prospects in being able to convince a significant portion of society to stop eating meat from factory farms in the near future. Plus, activist groups have been highlighting the lives of animals for many years, but per capita meat consumption in the U.S. has actually *increased* over the past twenty years. So I question whether we really have any good evidence to believe that we can sway public practices on meat eating enough to get rid of the industry.

    2. From an activism perspective, the fight against a couple of the other problems with factory farms you mentioned have a particular advantage: namely, they are about our own self-interest. That is, the health problems with factory farming threaten our own well-being. The environmental problems also threaten our well-being, although in a more long-term sense. So I don’t think that eliminating the suffering in factory farms would get rid of the impetus for fixing these other problems. As long as factory farms are a threat to our health, activists will have strong arguments against them.

    3. Finally, let’s just assume that it’s true that eliminating suffering holds us back from fixing the other problems. Is it really acceptable to cause millions of animals to suffer while we’re waiting to fix these problems? I suppose it depends on how you weigh different interests, but my answer is “no.”

  5. Eric Thomson

    On the cost issue, I would imagine that the biopharm companies that
    generated these strains might do something like sell sterile cow embryos to farmers to stop them from breeding. Sort of like selling GE corn whose seed is not viable. OTOH, that would be a hell of a lot of embryos.

  6. You note above that this would eliminate only pain-related suffering, and not other kinds of suffering – suffering due to fear, for instance, or suffering due to unnatural confinement. I wonder how important the pain component of factory-farmed animals’ suffering is. (Sorry if you talk about this in the article – I only read the abstract.) I’m inclined to think (on not a whole lot of evidence) that the pain component isn’t significant enough for your suggestion to improve the moral stature of factory farming much. Are you aware of any evidence relevant to this question?

    This all reminds me of the cow in The Restaurant at the End of the Universe… Nice post!

  7. Carrie Figdor

    I would like to add or second a few comments:

    First, the fact that meat-eating has gone up over the past few decades likely has to do with prices going down, and doesn’t show that activism over that period has been ineffective. To the contrary, there has been a slow but steady slog towards public awareness of the horrors of factory farming (which after all is a recent development in the history of farming; the term “farm” still conjures images of picturesque homesteads).

    Second, knocking out the affective pathway knocks out caring about the pain, not the pain. This is about as non-adaptive as one can get. That’s not just dangerous for the individual animal during its entire lifespan but dangerous to other species should genetically engineered animals escape and breed with others. (Not a concern with animals ‘neutered’ in adolescence, but not all kinds are, and females aren’t.) A parallel might be cats that are engineered not to grow claws.

    Third, sadism on the part of factory workers would probably get worse. I think Eric is right on about that one.

    Fourth, and sadly, I think Adam is right that the more this becomes a self-interest issue (rather than one about the moral status of animals) the more something is likely to be done about it. Meat demand is pretty elastic, so if meat from genetically engineered animals is more expensive, then the people who now buy cheap factory-farmed meat will continue to buy what’s cheaper (namely, the non-engineered) unless all factory farms are required by law to use only engineered animals. Then doesn’t the market split into three segments? The non-engineered factory farmed, the engineered factory-farmed and the non-engineered non-factory (I don’t think anyone would bother with the fourth category). In short, how would this really help, barring (very unlikely) laws prohibiting the first category?

    Crazy at it sounds, I think the best option (not original to me, obviously) is finding ways to grow muscle tissue in large enough quantities to satisfy the demand that exists at current prices.

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