High school biology classes like to present the idea that life isn’t as clear-cut a concept as people often take it to be. One classic example is viruses. Like any parasite, they reproduce by taking advantage of a host, but really the host is doing all the work. Viruses don’t do much to sustain themselves either, they just kind of are.
There are other edge cases, often involving self-replicating proteins of various complexity. Are prions alive? What about RNA strands in an amino-acid-rich environment?
I think rotifers are an example of something clearly above my line for being alive. They do all the reproduction and sustaining activities involved in my personal idea of what a living thing does. However, there’s still some weirdness in exactly what makes them living.
I don’t have an actual deep understanding of how something can be alive. I vaguely understand that there’s some complex biological processes that happen, and these can more-or-less be described in terms of chemistry, and so on.
But this still doesn’t really satisfy as an answer to the question of abiogenesis: how something living can be made up of nonliving matter. Life seems intuitively qualitatively different, even though its fuzzy boundary might be evidence that there’s really just a spectrum of differences, and no “on-switch” for when something is living and when it isn’t.
There are many concepts with fuzzy boundaries, but few with the same sort of mysteriousness as life. I think one good candidate is consciousness.
My thinking as of right now is that consciousness seems like it has the on/off switch that life doesn’t really have. For example, even at my most sleepy, there’s something different about being awake and conscious vs. asleep and un-.
However, the more I read about it, the less confident I am in that idea. I’m starting to think there’s a good chance that consciousness exists on a life-like spectrum and that it’s possible to have weird edge cases that wouldn’t clearly fall on one side or the other, sort of like viruses.
I also wonder what the minimally known-conscious creature might be. Analogous to rotifers for life, maybe there’s some animal that I could point to and say “I’m very sure this meets my requirements for consciousness”. I don’t think rotifers qualify. I do think dogs probably qualify. My line would be somewhere in between. Maybe the infamous bat, if there’s something it’s like to be one.
This also brings up another point. What is it that makes rotifers seem “minimally” alive whereas I would say that humans are without a shadow of a doubt completely alive? It can’t be the requirements for life, since I already said rotifers clear that bar. What more is there to life than life? Maybe this is anthropocentric thinking, imagining humans at the top of some hierarchy. Once you’re alive, you can’t be more alive. I’m misplacing rotifers at the bottom of a hierarchy that should have humans and rotifers at the same level.
Applying this to consciousness, weirdly I find my thinking goes in the other direction. I (at least used to) think there’s legitimately something to the idea that humans are really, really conscious, whereas dogs are merely conscious. If the analogy between life and consciousness holds, then my thoughts on either life or consciousness (or both) are really confused.