I Want To Know What "more Closely Related" Means And How That Came To Be And Why That Matters And To

i want to know what "more closely related" means and how that came to be and why that matters and to who

as funny as it is to say, "there's no such thing as a fish" is not actually true

"science doesn't know what a fish is" is really not true

"fish" is not a monophyletic category. there is no common ancestor of everything that we call a "fish," and none of the things that we don't

"fish" is a paraphyletic category -- and a useful one! marine biologists use it! "fish" describes a general body plan and lifestyle. it is useful to be able to talk about coelacanths and tuna in a shared category, though coelacanths are more closely related to us than to tuna.

where this bugs me is the repetition of the idea that "scientists" are hidebound and uncreative, unable to comprehend anything that doesn't conform to a specific idea of categorization -- when this is fundamentally untrue! we know perfectly well what a "fish" is. the fact that it's a paraphyletic group is only confounding to pop science, as a funny factoid, not to anyone who actually understands what a paraphyletic group is.