“AL” is pretty bright, but sometimes has his head up his ass. Oh, A I. That’s why we need serifs, dammit!
Data is data. Evidence is in interpretation. Yes, biology has a lot of maps. That’s the thing with nature - it doesn’t want to fit into neat boxes. But it’s humans tend to like neat boxes to organize our “stuff”. Ideas are “stuff”.
“Species” is a nice human box that nature tends to ignore.
Concepts like “ring species” test the notion of interbreeding. Fertile hybrids like coyote-wolves and polar-grizzlies strain it the other way.
And yes, “fish” is a pre-scientific label for anything from the water. It also is used for a basic shape of sea critter. Except we made scientific carve-outs like whales.
None of that negates the comprehensive understanding that Evolutionary Theory provides to biology.
Some random ramblings on ‘fish’, because I’m bored:
Traditionally, “fish” have been identified as belonging to one of three vertebrate Classes:
Agnatha (“jawless fishes”)
Chondrichthyes (“cartilaginous fishes”)
Osteichtyes (“bony fishes”)
The problem there is that two of those three groups are paraphyletic - that is, they do not include all the descendants of a parent group.
Agantha (mostly extinct critters, but with some extant clades such as hagfish and lampreys) is paraphyletic because all veterbrates evolved from aganathan ancestors. So, taxonomically, either Agnatha is paraphyletic (and thus not much use for inferring evolutionary history), or, if one wished to make it monophyletic and include all the descendants, it becomes synonymous with Vertebrata which is not particularly helpful.
Chondrichthyes (sharks, rays, etc.) is a monophyletic clade, so we’re good here.
Osteichthyes contains two main groups of “fish”: Actinopterygia (ray-finned fish) and Sarcopterygia (fleshy-finned fish). Actinopterygia is monophyletic (The vast majority of what people tend to associate with “fish” are probably Actinopterygians); Sarcopterygia…not so much. Since terrestrial vertebrates (aka Tetrapods) originate from this group, excluding them to only include aquatic members makes them paraphyletic.
So, on the one hand, we can say that “fish” is simply taxonomically invalid because it is paraphyletic. On the other hand, we can add some qualifiers, sort of how “non-avian dinosaur” has become vogue when talking about the “traditional” dinosaurs once we started (properly) grouping birds as dinosaurs; thus, we can say that “fish” includes all non-Tetrapod vertebrates. Still not terribly useful scientifically, but it can be useful as “short-hand” taxonomy. And it then excludes invertebrates, such as molluscs, echinoderms, sea jellies, etc., and an assortment of other swimmy things (e.g., sea snakes, amphibians, cetaceans, etc.). Not that that valid taxonomy has ever stopped folks from referring to “shellfish” and “starfish” and “jellyfish”…
Everything above is correct, and I’d like to make explicit a useful concept: grade. A “grade” is a fuzzy collection of features that describe what a species does and how. The stereotypical grade is “fish”, that is basically that any animal that moves about in the sea. Or, “tree”, which is any tall self-supporting plant.
A grade is useful for communicating with other people. “I caught a fish while sitting under a tree” is a useful statement in some contexts even if “fish” could mean Glyphis siamensis or Henicorhynchus siamensis and “tree” could mean Pinus palustris or Quercus palustris. We don’t often need scientific precision when describing our afternoon’s pasttime.
In terms of utility in describing evolutionary history, the clade, a group of organisms descended from a common ancestor, is superior. Scientists use typically use clades because nature doesn’t make sense without taking into account evolution and using clades makes that easier.
The most famous example of a sarcopterygian fish is the coelacanth (Latimeria sp.).
And, of course, while sea snakes aren’t, strictly speaking, tetrapods (in that they have no pods, much less tetra of them), they are members of Tetrapoda.
Something in evolution I find interesting is that very few herd animals stick together in a fight. Wild pigs, cape buffalo, musk ox, and elephants are a few that I can think of. If they did stick together, they would quickly overpopulate and eat themselves out of existence. I wonder if there were periods during evolution where more animals stuck together to fight off predators. Not sure about the American bison but I know they will fight predators..
Before this thread, I hadn’t seen you post in a long, long time (maybe we just inhabit different parts of the Board). I just want to say, it’s great to see you back! Your posts on evolution are really fantastic.
Indeed. This is a common tactic used by people who are wrong, but will not let evidence sway them. Their opponents try to explain the science, and then decide that the person who is wrong isn’t worth the effort. The person who is wrong proclaims victory. But they didn’t win the argument. They lost the argument by demonstrating that they will never see reality.
An argument is won if at least one participant, and preferably all participants, involved in it come away with a deeper understanding of the matter. Any other definition of victory is Calvinball.
This thread, and especially the OP’s username brought to my mind the Hans Christian Andersen story, “The Emperor’s New Clothes” for some reason. That Emperor was very much unclad, and also very much unwilling to observe the obvious.
Thanks! I took a break from the board back in 2016 for mental health reasons, but came back earlier this year. Still getting used to the new look and feel, but glad to be here!
