1,000Here's a bit of a wander. The ol' "chicken or egg" thing assumes that there must be some first chicken. That is, the beginning of a new species must have some defining moment where the global chicken counter first rolls from 0 to 1.
That assumption is rubbish, and is an artifact of humans trying to impose our thoughts of how things "should" work onto a system that gives no fucks at all about what we think of it.
The concept of a chicken -- the very concept of a species -- is not what most people think. A species is a cluster of organism with very similar traits (genes), and the boundaries between closely-related species are arbitrarily vague. Mind you, at least two species will be very closely related when we're talking about a new species emerging.
Picture a high-dimensional space where each axis of the space represents a different trait (morphological or behavioral). Put all organims in that space. Make some decisions about how many clusters you want and partition that space into clusters. Decrease the number of target clusters and you've got kingdoms. Increase it and you've got species. Increase it some more and you have subcultures (e.g. dolphins that blow ring bubbles). Prioritize some traits more than others to partition the space in different ways.
The first chicken would be nearish the edge of one of the clusters. It wouldn't have been alone there. It, and all of its cousins and second cousins, etc. would be on that edge. Squint and maybe it's a separate thing?
Some of the organisms on the opposite side of that cluster wouldn't be interested in our little chicken-ish friend; he's a bit too different for their tastes. Well, maybe if they were desparate, but definitely not their first choice, and maybe not even their 10th choice if we're being honest. But that's for those on the other side of the cluster. On the near side, he's looking pretty agreeable.
Eventually, a proper clevage develops. The far side of what used to be a cluster is really uninterested now. Both edges might still hook up with someone from the middle (if they were desperate), but both sides of the clevage really prefer their own.
Give it a few thousands more generations, and maybe aome geographic separation, and we've eventually got a new species.
That's what came first. Call it what you will.
@DanHomerick arguably you could define it by all the genomes that could produce gametes which if combined with gametes from the type specimen of chickens would produce fertile offspring
@TheAllMemeingEye that is one more way to partition the space, sure.
Early on, scientists divied up the space by some mix of morphology and geographical range. Later, we could analyze genetics and partition along new axes.
Science has discovered patterns and some natural structures, then applied names and categories in order to make it more understandable. All taxonomy is a sort of lossy compression, reducing the volume of data to something more manageable.
Sorry if I'm being boring, btw. I'm using writing as a way of thinking through some of this, and while it's interesting in my head, I'm not so sure it makes for interesting reading or a good conversation. :D
@DanHomerick I mean I'm neurospicy af so I might not be representative of the rest of the population lol
Personally I don't mind others writing out their chain of thought as long as it's possible for me to quickly figure out the main conclusions
In this case I would mentally summarise your conclusion something like "early zoologists and modern laypeople base taxonomy purely on subjective easily visually noticeable traits so arguably that's the truer definition for species"
@TheAllMemeingEye my main point was that our classification systems (i.e. "species") are human-invented things. Our classifications do a pretty good job at describing what we observe, but they are just a model of a more complicated reality.
Reality, especially when biology is involved, often lacks nice crisp boundaries.