Using the chicken-to-human results on this SSC post (https://slatestarcodex.com/2019/03/28/partial-retraction-of-post-on-animal-value-and-neural-number/) ( some of you may have seen it), I was interested in just how much more effective an ACE charity is over a popular Givewell one, like Malaria Consortium. I really do think that this animal vs human debate should be talked about much more, considering that (1) this is a very practical change we could all be making, and (2) it could make a huge difference.
So the first assumption that has to be made here is that 25 chickens = 1 human. Now intuitively this probably feels off to everyone that isn't a hardcore animal welfare advocate, even to me it still feels off, but let me try to explain why it could make sense. Bigger brains, like the human one, generally shouldn't scale linearly in moral worth because of diminishing returns. The huge number of cortical neurons humans have could just be going to processes like thinking, memory, language, things that don't contribute to the raw suffering that is necessary for moral worth. Even in nematodes with 300 neurons, we still see them have an averse reaction to predators, even the smell of them. This could mean that nematodes are experiencing some very primitive form of suffering that gives them a lot more moral worth than imagined. Or as better explained by this quote: "Neural network analyses show that cognitive features found in insects, such as numerosity, attention and categorisation-like processes, may require only very limited neuron numbers. Thus, brain size may have less of a relationship with behavioural repertoire and cognitive capacity than generally assumed, prompting the question of what large brains are for. Larger brains are, at least partly, a consequence of larger neurons that are necessary in large animals due to basic biophysical constraints. They also contain greater replication of neuronal circuits, adding precision to sensory processes, detail to perception, more parallel processing and enlarged storage capacity. Yet, these advantages are unlikely to produce the qualitative shifts in behaviour that are often assumed to accompany increased brain size."
Now the question is what chicken-to-human number do we use to compare the charities? The MTurk survey that one of Scott's readers used came up with 25, but what I use for comparison is a square root of neuron count, which is 15,000/293,000 = 20 chickens per human (chickens have 220 million and humans have 86 billion total.) This number is eerily similar to 25, which is a bit comforting. However this number is only looking at capacity to suffer. In order to compare this in duration, we have to compare a broiler chicken life to a full under-5 life saved by Malaria Consortium. That would look something like 6 weeks/40 years = 330*20 = 6600 chickens-to-humans. This number feels a lot more intuitively better now. The guesstimate model (https://www.getguesstimate.com/models/10636) here of THL gives an estimate of 18 animals "spared" per dollar (this is really just the 5% welfare improvement that equals a chicken). Malaria Consortium saves a life at around $2200. So the final calculation here would be 6600/18 = 1 "human" saved per $366. That's about 6x more effective than Consortium, and it's only using a 5% welfare improvement which sounds very low to me. So the call to action here would be to start pulling more donations to THL or another ACE charity. Even using very conservative estimates for welfare improvement, you still get a large inherent difference between animals and humans.