That cool bee book I was talking about a while ago mostly refrains from philosophical digressions (which I think is a strength, I appreciated how the author had total confidence that just clearly presenting the facts about his subject would be enough to make a fascinating book without the need for any "...and here's why that should blow your mind" editorializing, and he's totally right), but there was one towards the end I've found myself thinking about a lot, which is: he wants people to stop using "self-consciousness" (i.e. the concept exemplified by the mirror test but used implicitly or explicitly in tons of other contexts) as a criterion for which animals can be considered sentient/morally relevant/having significant inner lives/however you want to describe it. Not, as you might expect, because he thinks it's an unreasonably high bar to meet, but because it's such a low bar that it produces no distinctions: he argues that basically any animal with any kind of developed central nervous system has to have some kind of self-consciousness almost by definition.
The example I remember best is: imagine you can see an object in your visual field getting closer to you. No matter the specifics, it's obviously always going to make a huge difference to how you evaluate this situation whether the cause of the object getting closer is a] the object is moving towards you, or b] you are moving towards the object. If a, then something might be pursuing you or falling on you or a thousand other things that are just not even worth considering in the case of b. But visually the two cases are indistinguishable; if you're going to be able to track the difference, your brain has to be putting at least some work into keeping tabs on what your own intentions are and what choices you're making as you move through the world, predicting the expected consequences of those choices, and maintaining a fairly tidy mental separation between stuff in the world that you're making happen and stuff in the world that's just happening of its own volition. Otherwise, every time you walk towards a rock you'll freak out and think the rock is rolling into you, or vice versa.
And it's not hard to see how this applies to your entire sensory world right, it applies to sounds and tactile sensations and even feelings internal to your body to some extent, if you're going to both perceive the world and take actions in the world then it's mandatory to mentally separate yourself and the world before that's going to yield even an ounce of helpful information, you just can't function successfully on the most basic level if you're processing stuff that you're doing on the same level as stuff that's happening, if you're in that state then you simply don't have a usable model of the world at all, you just have chaos.
So you can very easily eliminate a certain seductive narrative about the evolution of consciousness, which starts with very primitive animals who are mentally processing nothing but basic sensory inputs, then as you rise up the chain more complex animals are forming concepts of objects and building up a more nuanced understanding of the world, until finally you approach humans and the mind becomes so subtle and sophisticated that it gains access to this special advanced meta-level of thought where it can even understand itself! No, the self is precisely the one idea that has to be in place from the very beginning, before any of it has even the most rudimentary practical value. Self-consciousness isn't the pinnacle of the mind's evolution, it's one of the lowest, most basic foundations that everything else builds off of.
I think this is really cool stuff! I don't know enough about the relevant academic philosophy of mind debates to say how far all this does or doesn't speak to that, maybe someone will tell me the "self-consciousness" concept being attacked here is a strawman somehow, I don't know. But it's definitely impacted the way I (just a dumb guy who likes creatures) think about our small small cousins and what their lives might be like and I think it's super interesting. If you think it's interesting too then maybe you wanna buy The Mind of a Bee by Lars Chittka and read it. It's mostly not about this stuff, as I say it's light on philosophy and heavy on bee-life immersion, but if you actually read this whole post then you're probably in the market for that I feel like.