> even vegans do not generally have misgivings about killing bugs in their house

This isn't my experience, and I certainly avoid causing harm to them.

> I expect "cease consuming meat" would be less effective messaging.

Absolutely, this would probably verge on being useless. If the objective is to reduce harm, I agree that the best we can do at the moment is aim for reduction rather than elimination (I suppose along with improvements to welfare and slaughter conditions).

> Sardines don't have a cerebral cortex

I really can't determine if fish can or cannot suffer as I do, but I have greater anecdotal evidence to support that they're very environmentally/situationally aware and able to suffer than I have evidence to the contrary. The longer I hunted them the more it became clear that they're quite curious, engaged, and aware. What this really looks like in relation to the human experience, I don't know. They appear not to be meat-robots at all, though. I began hunting them because I assumed they were less aware or able to suffer, but hunting them was a significant factor in me giving up animal products. This is purely personal and anecdotal, of course. Maybe I'm going crazy and anthropomorphizing fish.

Bivalves on the other hand... I do wonder if they are more like a plant than an animal in some ways.

In both cases, fish and bivalves, it only gains me moderate superficial gratification to kill and eat them, so it's more rewarding to me to avoid causing unnecessary death or suffering instead. I don't gain enough to justify what they could be losing (if it's unnecessary for my survival), I suppose.

> I expect most people, if you poll them, would say they favor measures to reduce harm to farm animals, even if they'd still consume them.

Absolutely. I have no doubt about that. From farmer to table, I suspect the vast majority of people involved would prefer that the animals never suffered at all. I don't see malice, animosity, or intentional cruelty in the agenda. I suppose that's part of why this is so hard; where ill intent is missing, it's very difficult to see the harm that could have been done despite good intents.

> including indigenous groups in North America

This is a tough one, because I have no right to tell others how to eat or behave, let alone a group of people who has arguably been disadvantaged and robbed of their cultural roots over generations. My wife works with indigenous people in coastal BC, Canada, and while many of them don't really have the means to live without fishing and hunting, some do, and I'm conflicted about the ethics of that. Frankly it doesn't matter what my take on ethics is – I'm an uneducated hypocrite on the internet – but I do think about it a lot nonetheless. Again though, as mentioned elsewhere, I don't condemn people for eating meat and I don't think indigenous people bear a moral impetus to stop hunting and fishing because I can conveniently afford all of the whole plant foods and supplements that I need. I do think it's ideal if they reduce harm and suffering as much as possible, but I can't say to which degree that should be enforced.

I also (perhaps due to bias) see something of a difference in hunting and fishing vs agriculture. In my experience with both, there has been a lot less suffering in hunting and fishing. At least, fishing with a spear. I don't think nets or jigs are a good way to go. It's all relatively fast, though. But similar to "who am I to judge one's culture", I have to ask, "who am I to decide the best way to die?". In this case I suspect I would prefer to live with agency and according to my nature, then die by chance rather than to live within the strict and typically abusive constraints and conditions of the system I will eventually be slaughtered in.

> The trees and plants are also sacred, it seems, but not so sacred that we can't reap some arbitrary amount

This is an important point I think a lot of vegans miss, and I think it should fall within the sphere of concern. Our love of shaping the earth and environment hurts stunning numbers of living things, from plant to insect to animal, and it benefits all of us in the short term. Myself included. I often wonder: why aren't vegans more upset about that component of our society? Why aren't we bothered that mass deforestation not only destroys animal habitats, but changes local water cycles and dramatically impacts watersheds in negative ways? Each tree, especially old growth, is a microcosm of life. They create biomes which enable diverse lifeforms to flourish. Removing them quite literally eliminates viable surface area for life to thrive upon from the planet, at least until a tree can grow back.

Isn't the consequence of deforestation potentially as harmful as many forms of animal agriculture? I rarely hear about it, but I suspect it causes the deaths of billions of animals both directly and indirectly every year. Damage to life in watersheds is immense and far-reaching, and deforestation plays a major role in it. As does all forms of agriculture, too; it requires serious attention.

> Pre-civilization is romanticized

Yes, and for too many reasons to count. I often see it as a reason to eat certain ways, be it vegan or carnivore, and I have to wonder... What do we think we would have eaten were it not for super markets and modern agriculture? My answer is anything that would keep me alive. I wouldn't care about macros or how gassy it made me. I wouldn't optimize my nutrition. Anything someone found in my fossilized poo would be irrelevant to nutrition. It would be what I ate to stay alive that day.

I have a feeling it's generally absurd to appeal to pre-history as a reference for current behaviour ideals. I'm sure a case can be made for doing it in some instances, but I can't think of any off the top of my head.