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The production of meat from an animal causes many problems: animal suffering, environmental impact (pollution, biodiversity loss, climate change) and infectious disease risks. These problems of animal-based meat are related to the organs of the animal (as shown in this infographic). Animal suffering relates to the nervous system, pollution relates to the urinary system (e.g. eutrophication), climate change and land use relate to the digestive system (e.g. methane emissions from stomach bacteria), infectious disease risks relate to the respiratory system (respiratory viral infections) and digestive system (harmful gut bacteria). 

As a better alternative to animal-based meat, a lot of hope is placed in cultivated or cell-based meat: producing the muscle tissue without the animal. The idea is that as the problematic organs (brains, stomachs, lungs,…) are not produced, the animal welfare, environmental and public health problems could be avoided or decreased. 

There is a lot of debate about cultivated or cell-based meat feasibility, in particular whether it can be produced as cheaply and efficiently as animal-based meat. In this article, I want to point at the crux of that debate and argue that cell-based meat research and development remains important as a kind of insurance policy. 


Function, product and production process

We first have to make the distinction between the function, the product and the production process. When it comes to meat, consumers have preferences about taste, texture, nutritional value or ease of use. These are the functions of a product. Many different products can fulfill these functions. Currently, most of the preferred functions are fulfilled by muscle-based meat: meat made from muscle tissues of chickens, pigs and cows. Alternatives are e.g. plant-based, algae-based and fungi-based meat products. For simplicity, all these non-muscle meat products will be referred to as plant-based meat. Given a specific product, there are different production processes. For example muscle-based meat can be produced using an animal (animal-based meat) or using a bioreactor with muscle cells (cultivated or cell-based meat). 

The animal welfare, environmental and public health problems relate to the production processes. That means we have to move away from the bad animal-based meat production process towards better production processes. There are two strategies: either we switch to a new product, such as plant-based meat, or we stick to the same product of muscle-based meat, but change its production process. 

The first strategy, substitution of muscle-based meat with plant-based meat, is the approach currently followed by most environmental and animal activists. The advantage of this approach is that the production processes of basically all plant-based meats are already better than the production process of animal-based meat. 

However, it remains a question whether all consumers are willing to completely switch towards those plant-based meats. This involves switching to new products, and some consumers are reluctant to make such switches. It could be that the muscle-based meat product fulfills another function, such as tradition or familiarity, and this function cannot be fulfilled by the alternative plant-based meat products. If such a function is strongly present, muscle-based meat and plant-based meat cannot be considered as complete substitutes, but have a degree of complementarity. This complementarity means that people are going to consume both muscle-based and plant-based meat, but not eliminate muscle-based meat from their diet. It means that animal farming will not be abolished, at least in the short run. In the long run, perhaps after several generations, the tradition and familiarity functions of muscle-based meat might gradually disappear, which means there is a slow shift towards 100% plant-based meat products. This could take decades.

The second strategy of innovation is followed by the technology optimists who believe in the feasibility of cell-based meat. The advantage of this strategy is that people can still buy the same product: they do not have to change their behavior or consumption choices. It is comparable to a switch of brands. Only the production process differs, but this production process is not observed by consumers. And as the same product fulfills the same functions, consumers generally do not have a direct or pure preference for a production process. (Of course, their preferences for animal welfare, environment or health can generate an indirect preference for a production process.) 

However, it remains a question whether cell-based meat is feasible, and if it is feasible, whether it enters the market fast enough. The next section argues, based on ‘first principles’ or mere reasoning (without requiring empirical research or techno-economic assessments), why cell-based meat is expected to be feasible in the sense that it can sooner or later reach price parity with animal-based meat.


Why cell-based meat is likely feasible

The basic idea is that animals were not evolved to maximize meat (muscle tissue) production as efficiently as possible. 

Consider the function of carbohydrate metabolism regulation. This function can be fulfilled with a product: insulin. People with diabetes need to take this product that can be produced in different ways. The old production process used pigs, but as with muscle tissue, pigs are not evolved to maximize insulin production as efficiently as possible. A new production process uses recombinant-DNA yeast cells to produce insulin. This is much more efficient and cheaper. Here we see a concrete example of a shift in production process, from animal-based to microbe-based, keeping the same function and the same product.

There are three reasons why cell-based meat can have a more efficient and cheaper production process than animal-based meat. 

First, the animal wastes resources (nutrients, energy) on unnecessary organs, tissues and body parts, such as brains, eyes, ears, tails, feathers, pain receptor cells, reproductive organs, hooves,... All these body parts are not necessary to grow muscle tissue. Assume that these unnecessary body parts use 10% of nutrients and energy. Then a production unit (e.g. a bioreactor) that does not use these body parts can be 10% more resource efficient. If resource costs count for half of the total production costs, this means a cost reduction of 5%.

Second, the remaining body parts that are necessary for muscle tissue growth, can be replaced by new technologies (products) that fulfill the same function at least as efficiently, but do not have to be replaced after each production cycle. The function of oxygenation can be fulfilled with a respiratory system (an organic product called lungs), but also with other technological products such as oxygenators. The function of nutrient and growth medium production can be fulfilled with an organic digestive system or with new nutrient production technologies. Removal of waste products from the growth medium can be done with an urinary system (an organic product called kidneys) or with other waste removal technologies.

Using an animal to harvest muscle cells, the many other body parts that are necessary for muscle growth, such as the lungs (for oxygenation), intestines (for production of the growth medium), skin (for thermal isolation and protection),... need frequent replacement when the muscle cells are harvested, because these body parts are destroyed (in the slaughterhouse). It is like using a bioreactor to grow cultivated meat, and after each batch, we destroy the whole equipment, including all sensors, tubes,... And then we built a new bioreactor (using a factory that fulfills the same function as a uterus). That would be very inefficient and costly. Not having to construct a new production unit after each production cycle will make cultivated meat production much more efficient (and hence less costly) than animal-based meat. 

Assume the production unit for animal-based meat (the necessary body parts for muscle growth) consumes 50% of resources for its construction (growth). In that case, not having to construct so many production units could save almost 50% of resource costs. This estimate assumes that all biological functions in an organism can be replicated with technologies, and that these technologies can reach the same efficiency as the biological functions that reached high efficiency due to evolution and natural selection. That is a realistic assumption, because no laws of nature have to be violated. We already know that such levels of efficiency are achievable by a blind process of evolution.

Third, it is unlikely that the organic body parts fulfill their functions with maximum attainable efficiency that is possible by the laws of physics. There are for example thermodynamic boundaries on efficiency, but it would be a strong coincidence if all organs of a currently alive farm animal would have maximum efficiency. That would mean current farm animals reached the end of evolution and their body design is optimal.

There are plenty of examples where functions became more efficiently fulfilled by technologies than by organisms. Photovoltaic solar panels are more efficient in capturing solar energy than plant photosynthesis. Airplanes are more efficient in flying than birds. Cars are more efficient in heavy transport than horses. Hence, it can be expected that at least some of the functions of e.g. oxygenation, growth medium production, fat production, growth medium circulation, waste removal, thermal isolation and immunity can be more efficiently performed by synthetic technologies than by their organic counterparts such as the lungs, guts, liver, heart, kidneys, skin and lymph nodes. Once a technological product becomes more efficient than an organic product in fulfilling the required function, costs of the cell-based meat production process decrease relative to animal-based meat. It is unlikely that none of the technologies can become more efficient than their organic counterparts.

Given the above considerations, we can expect that with sufficient research, it is only a matter of time when cell-based meat enters the market, reaches price parity with animal-based meat and even becomes cheaper than animal-based meat. If it is as cheap, cell-based meat can be considered as a complete substitute for animal-based meat, as it fulfills all animal-based meat functions. Once it is cheaper, we can expect that consumers completely switch to cell-based meat. 


Innovation versus substitution: cell-based meat as an insurance policy

Now we come to the crux of the cultivated meat feasibility discussion. Is technological innovation of the cell-based meat production process faster than product substitution towards plant-based meat? Both innovation and substitution will take many years. But if muscle-based and plant-based meat products are highly substitutable, which means they fulfill the same functions such that consumers are willing to switch, it is possible that the meat market completely shifts towards plant-based meat before cell-based meat enters the market. That means any investments in cell-based meat research and development would be futile and wasted (although there may still be a market for cell-based meat for carnivorous animals, such as cell-based mouse meat for cats). 

There is high uncertainty about the expected time frames of both innovation and substitution. We do know that younger generations are more willing to eat plant-based meat and older generations prefer sticking to muscle-based meat. This could mean that a complete switch towards plant-based meat could take a few generations, a time frame of a century. But also innovation of cell-based meat could take many decades before whole tissue cell-based meat becomes cheaper than animal-based meat. 

The substitution strategy seems risky, because the current rate of substitution reflects the low-hanging fruit: people who are easily willing to switch to plant-based meat. This current rate of substitution does not offer evidence concerning the final stage of substitution: whether the more tradition-inclined, conservative people who are meat identifiers, who do not believe that plant-based meat is real meat, and who have food neophobia (fear of new food products such as plant-based meat) are willing to switch to plant-based meat.

The innovation strategy seems risky, because the current rate of innovation does not offer sufficient evidence whether future research is able to overcome foreseeable big obstacles (such as increasing cell density in bioreactors, avoiding bacterial infections,…). 

Given the uncertainty about the innovation and substitution strategies, there is not enough evidence to prioritize one strategy over the other. 

It is possible that a small fraction of the population (e.g. 1%) are really reluctant to switch to plant-based meat and will continue eating animal-based meat. As the current number of animals used for food is very big (hundreds of billions per year, if we include fish), even a small fraction of the population still eating animal-based meat corresponds with the suffering and killing of huge numbers of animals (billions per year). If we stop investments in cell-based meat innovation, we risk the continuation of the suffering and killing of many animals. But there remains a possibility that cell-based meat innovation is superfluous, that everyone will have switched to plant-based meat before cell-based meat reaches price parity with animal-based meat. That is why cell-based meat innovation can be considered as an insurance policy, in case plant-based meat fails to completely switch the meat market. 





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The core of our disagreement seems to be here:

This estimate assumes that all biological functions in an organism can be replicated with technologies, and that these technologies can reach the same efficiency as the biological functions that reached high efficiency due to evolution and natural selection.

I don’t think this is realistic. Perhaps in isolation you could build systems that efficiently accomplish some of these functions, but in the case of cultured meat they all have to be compatible with/support the growth of animal cells and tissues. This is an enormous handicap. All of the technologies you cite as analogous (solar panels vs plants, cars vs horses, planes vs birds, recombinant vs porcine insulin) represent new approaches that are completely free from the limitations of the biological systems they’ve replaced. I don't think any of them should be counted as precedents for the type of innovation cultured meat would require.

Yes this is what I meant by "cars are not mechanical horses" in an earlier thread, thanks for putting it in more precise terms. 

I think I have two related counterarguments to the OP:

1) the car vs horse and plane vs bird reference classes/analogies seems to me to be moderately strong or even very strong evidence that humans are eventually capable of something that can accomplish what nature does cheaply and well, but only weak evidence for any specific strategy. Maybe plant-based or cultured meat is how we get there, but maybe it'd look entirely different.

2) If anything, the history of human progress in trying to imitate nature is anti-evidence for strategies that look like cultured meat (taking a highly coupled system from nature and then trying to mechanically replicate nature in a very similar way to how nature does it). Notably we do not fly around in ornithopters, most progress in AI doesn't look like brain scanning and replication, and we still haven't figured out giant mechs to ride around (cool as they may seem).

The more I think about it, the more I start to believe that cultivated meat is feasible, and that your examples offer some evidence.

So consider the function of flying. You may say that the function of flying with wings cannot be fulfilled with technology, that  imitating nature does not work . But your examples refer to humans flying with technologies that use wings. But humans are much heavier than birds. With airplanes, we can fly faster, over longer distances and carry heavier weights, things that biological organisms were never capable of doing. And we are talking about many orders of magnitude faster, further and heavier. Why would the functions necessary for muscle cell growth (e.g. oxygenation, nutrient production, waste removal,...) be any different? Why would these functions never be able to be fulfilled at least as efficiently with technologies than with organs?

Then you offer the example of ornithopters, and I conclude that even imitating nature is possible. The function of flying with wings can be imitated with technology. Those ornithopters are as heavy and large as birds. Some of those ornithopters even use artificial muscles (polymers that can contract like muscles). So the function of muscle contraction can also be replicated.  Some ornithopters have machine learning AI such that they can learn to fly, which means the function of brains can be replicated. So the complex combination of functions "learning to fly with wings using muscle contractions" can be replicated. What more evidence do you want that technology can build tools that fulfill complex functions that are fulfilled by biological organisms?

What evidence would cause you to change your mind? 

Thanks for the question, had to think a while. About infeasibility of cultivated meat, best counterevidence for me would be seeing a massive disinvestment in cultivated meat R&D, a consensus among researchers openly saying that it is too difficult to make progress.

Another crucial thing that would change my mind, is evidence about the feasibility of plant-based meat, that substitution towards plant-based is faster than I would expect (faster than cultivated meat innovation). This would mean seeing a fast increase in the number of vegans, and especially conservative male meat identifiers switching to plant-based meats.

Ok, thanks for that!  Things that will update my mind include:

Social proof: The biggest thing that will change my mind is if Open Phil science team or other EA researchers that I trust generally update towards cost-competitive cultured meat being the most viable and plausible route to reducing factory farming (among many possible options). Of course that might be too late to be useful; I will also update somewhat if the top biotech VCs made major investments into cultured meat, and (to a noticeably lesser extent) if the most prestigious traditional VCs made significant investments in the sector. I will probably also update if top ~10 Metaculus forecasters or other top forecasters a) believe something very different and b) demonstrated to me that they spent considerable time looking into this. 

Near term costs that aren't VC etc subsidized: Humbird's analysis claims costs of >$200/kg using wild-type animal cells, so if I see credible evidence of <$100/kg in the near future (say next 3 years), I'd consider that a moderate refutation of Humbird's model, even though his endline numbers were lower. At the very least, I'd want to dig into how they did that. If they did it entirely through metabolic engineering improvements, I'd consider this less of a ding against Humbird than if they did it through other efficiencies.

Amino acid + other input prices: There are a number of things that will update me towards providing/using cheap amino acids is easier than I thought. Eg, Humbird thinks you need very pure amino acids to grow cultured meat. Many cultured meat proponents think you can do it with less. But this is an empirical question: You can just try to make cultured meat using less optimal concentrations of amino acids. There are a number of other statistical tests and empirical arguments that can convince me. 

Hygiene: I think I can change my mind if I see either direct or indirect evidence that cheap hygiene at scale is much easier than I think.

Conceptual/analytic framework: On the conceptual level, the thing that will change my mind in terms of whether I'm framing this correctly includes a) if somebody empirically demonstrates that with a more accurate construction of reference classes, things that look like cultured meat (mechanical horses) are actually quite common in the wild. Or b) somebody logically or conceptually convinces me that my current categorizations of this car vs mechanical horses vs selectively bred horses ontology is confused/broken for reasons I don't currently understand.

Comprehensiveness of search for alternative options: I don't think of plant-based meat as a large crux, and certainly not vegan identification. I think I'll be forced to be relatively more bullish on cultured meat if I see that reasonable people already did a comprehensive, first-principles-based search on ways to reduce animal suffering and landed on cultured meat and plant-based meat as the best methods they can find; right now I just think people are way too overindexed on existing ways of doing things (see eg the Decisive book or specifically my notes on "Narrow  Framing").

Not to over-emphasize this part of the debate, but I don't think future cultured meat systems will be that analogous to how they look in animals. For example, modern bioreactor systems often employ a "sterile boundary" approach to sterility, which is pretty different than using antibodies to attack foreign  particles. Depending on what bioreactor system you use, there are lots of things that look pretty different than what happens inside an animal.

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