We're all fish (seriously)

[mikeynov]

So, the other night on instant messenger, a cousin of mine asked me to tell her something interesting. So I decided to explain why she and I are fish (note: more particularly, a subset of a group typically referred to by the colloquial term "fish"). She totally didn't understand what I meant, so I tried to explain the nature of cladistics and what it means for any given taxon to be monophyletic (i.e. arising from a single ancestral population). That wasn't working so well, so I ended up drawing a picture.

The original picture I drew was bordering on the stupid and used clades not generally considered to be monophyletic (e.g. reptilia), so I just spent 20 some minutes making a new one that uses only officially recognized, probably monophyletic clades. The source of this information was CF's own L. Aron-Ra, who has done a lot of footwork for this stuff, including detailed examples and illustrations which can be found at his website here.

Anyways, here's the still-dopey picture I came up with to try to explain why we're all fish. The logic here being, of course, that evolution works to create daughter branches of any clade by using modified forms of the raw material of the parent clade. In short, any evolutionary branch of a given clade will always be a subset of that clade.

So, given that the sarcopytergians are ancestral to all terrestrial vertebrates, and that the sarcopterygians are themselves fish, that makes all terrestrial vertebrates a subset of sarcopyterygian fish. And that's why we're all still "fish," as it were.

I'll also include Aron's (updated) list of descriptions for these clades, which he has given me permission in the past to reproduce:

An organism is any organic (Carbon-based) RNA/DNA protein-based structure which replicates & reproduces.

One subset of organisms is Biota, living organisms, which are defined as any of the above which can also maintain metabolic homestasis, a balanced internal chemical environment.

One subset of that is Eukarya, metabolic organisms with nucleic cells.

One subset of that is Opisthokonta, Eukaryotes who's gammete cells have a single flagellum mounted in the rear, (pushing) postion.

One subset of that is Metazoa, (Kingdom, Animalia) multicellular opisthokonts which must ingest other organisms in a digestive tract in order to survive.

One subset of that is Eumetazoa, which includes all animals more advanced than sponges.

One subset of that is Coelomata, eumetazoans with an tubular internal digestive cavity.

One subset of that are Triploblasts, Coelomates with three germ layers.

One subset of that is Bilateria, triploblasts which at some stage of development are bilaterally-symetrical.

One subset of that is Deuterostomia, bilateral animals in which fetal development of the digestive tract begins with a blastopore which opens anally first, and then orally.

One subset of that is Chordata, Deuterostomes with a spinal chord.

One subset of that is Craniata, Chordates with a brain enclosed in a skull.

One subset of that is Vertebrata, Craniates with a spinal vertebrae descending from the skull.

One subset of that is Gnathostomata, Vertebrates with a jawbone.

One subset of that is Osteichthyes, being essentially Gnathostomes who's skeletons are predominantly calcified into bones.

One subset of that is Sarcopterygii, which are teleosts that have both lungs and legs.

One subset of that are the Stegocephalians, which are Sarcopterygiians with digits on the ends of their appendages.

One subset of that is Tetrapoda, gill-less Stegocephalians which are skeletally-adapted for four limbs.

One subset of that is Anthracosauria, which are pentadactyl primarily-terrestrial tetrapods.

(NOTE: Humans still conform to all of these clades. But there are some other lineages where the number of digits, limbs, or other features may have been lost, or which are no longer primarily-terrestrial; snakes and whales for example. But in such cases, they are still considered anthracosaurs because their overall structure indicates that it was originally designed for five digits, four limbs, and terrestrial locomotion. You can change any number of features, but one thing you can never change is your ancestry. Logically, you will always be part of your ancestral family no matter how different from them you might have become.)

One subset of Anthracosauria is Amniota, dry-skinned anthracosaurs which developed in amniotic fluid, and which have keratinized digits, (claws, fingernails, hooves).

One subset of that is Synapsidae, amniotes with a single temporal fenestra.

One subset of that is Therapsida, synapsids with mammalian skeletal formations.

One subset of that is Theria, (mammals) endothermic (warm-blooded) therapsids with lactal glands.

One subset of that is Eutheria, mammals which are born in a placenta, and which have nipples.

One subset of that are Euachontoglires, eutherians with generalized [primitive] but modernized skeletal features.

One subset of that is Archonta, euachontoglires with delicate fingers, a clavicle (collar bone), and forward-oriented eyes with orbits (eye sockets) completely encircled by bone.

One subset of that is Anthropoidea, (primates) hind-leg dominant Archontids with opposable thumbs, a shortened rostrum, large braincase, an unfused and highly mobile radius and ulna in the forelimb and tibia and fibula in the hindlimb.

One subset of that is Haplorhini, (monkeys) anthropoids with binocular vision, a pendulous penis, a well-developed caecum, an large brain, two pectoral mammae, and a tendancy toward bipedalism.

One subset of that is Catarrhini, (Old World monkeys) with elevated intelligence, downturned nostrils, flat fingernails, and without prehensile tails. Catarrhine monkeys are also one of the few animals intelligent enough to recognize a reflection of themselves.

One subset of that is Hominoidea, (apes) tailless Catarrhines having a tendancy toward a bipedal gait, with oversized brains, and individually-distinctive fingerprints on arms with a shoulder arc capable of brachiation and complete rotation.

One subset of that is Hominidae, (Great apes) "large" apes with especially large, unusually intelligent brains capable of comprehending language, or of making and using simple tools; having color vision, relatively sparse fur, an inability to synthesize vitamin C, and a unique dentition which includes 32 teeth consisting of incisors, cuspids, bicuspids, canines, and molars, the latter of which have four roots, and come to five points interrupted by a Y-shaped crevasse.

One subset of that is Hominini, (also known as humanoids) exclusively bi-pedal great apes.

One subset of that is Homo, (humans) Hominines with enormous brains, and an ability to articulate speech, and explore more complex technologies.

One subset of that is Homo sapiens sapiens, modern man, a group which simultaneously conforms to all the criteria for every one of the groups-within-groups, (taxonomic clades) listed above, and are therefore a member of each of these groups.

 

[AnEmpiricalAgnostic]

Cute.. so that's why we have gills for awhile in the womb

 

[mikeynov]

Cute.. so that's why we have gills for awhile in the womb

Well, pharyngeal slits. Don't want to upset the Icons people...

 

[Split Rock]

Ha!

I Am Not A Fish!

You Can't Make A Mackerel Outta Me!!!!!

 

[tryptophan]

I read this at http://www.ncseweb.org/icons/Icon5archy.html.

Returning to Archaeopteryx, Wells then resorts to a classic creationist taxonomy game. In this game, the creationist says that scientists have to choose whether a fossil belongs to one taxonomic group or another. So, in the case of Archaeopteryx, it has to be a bird or a reptile. Then the creationist says that because it has feathers it is a bird, and therefore because it is a "bird" it cannot be a transitional form. In effect the transitional features of the fossil are defined out of existence. This is a classic creationist ploy, and nothing new; it is what we have seen for decades from Duane Gish and Henry Morris. Wells uses a slightly different approach, claiming that if Archaeopteryx and birds are just dinosaurs, then humans are just fish, which -- he implies -- is absurd. But this is another case of Wells trying to use semantics to negate the evidence of evolution, just as he did with the Cambrian Explosion.

Here Wells exploits the systematic practice by which all groups of organisms must be "monophyletic," that is, consist of an ancestor and all of its descendants. In Wells's rather naïve example, "fish" must be taken to include hagfishes, lampreys, sharks, goldfish and other rayfins, coelocanths, and lungfishes. If "fish" were defined that way, then tetrapods (all animals that have four limbs) would indeed be "fish" and "fish" would become another name for "vertebrate." But "fish" is not a taxonomic name; it is a colloquial term, and as a Ph.D. biologist, Wells should know that. Real systematists don't use the term "fish" except in a restricted sense referring either to a subgroup that is monophyletic such as Actinopterygia or to "rayfins" (things like goldfish, trout, swordfish, etc.) -- the vast majority of living "fishes." Humans are vertebrates; so are fishes. Birds, by phylogenetic relationship, are dinosaurs. Just as dogs are canids, and also mammals, and also tetrapods and vertebrates. Consider a mailing address: just because you live on 1010 Main Street does not mean that you don't live in Peoria or in Illinois, or that someone living on 411 South Street doesn't live in the same town or state.

According to this article, fish isn't really a monophyletic group, hence we would not be classified as fish.

 

[mikeynov]

I read this at http://www.ncseweb.org/icons/Icon5archy.html.



According to this article, fish isn't really a monophyletic group, hence we would not be classified as fish.

I explained this in my first post. We're a subset of a particular kind of "fish," the sarcopytergians, which are in turn a subset of osteichthians, which are in turn a subset of the "jawed fish," the gnathostomes. So, we're simultaneously a subset of all of those groups, which most certainly are fish. But I WASN'T using "fish" as a monophyletic group, nor was I attempting to.

Note: this was originally supposed to be half-funny, but ended up being a decent exercise in refreshing my understanding of the particular taxonomy relevent to human evolution.

 

[tryptophan]

I explained this in my first post. We're a subset of a particular kind of "fish," the sarcopytergians, which are in turn a subset of teleosts, which are in turn a subset of the "jawed fish," the gnathostomes. So, we're simultaneously a subset of all of those groups, which most certainly are fish. But I WASN'T using "fish" as a monophyletic group, nor was I attempting to.

Note: this was originally supposed to be half-funny, but ended up being a decent exercise in refreshing my understanding of the particular taxonomy relevent to human evolution.

oops. sorry. must have missed that.

 

[JohnR7]

So, we're simultaneously a subset of all of those groups, which most certainly are fish. But I WASN'T using "fish" as a monophyletic group, nor was I attempting to.

I hope you realize that you just falsified the theory of evoluion. Your trying to claim that this so call missing link or missing common ancestor had all of these traits and then for some reason distributed them all out to the different species?

 

[notto]

I hope you realize that you just falsified the theory of evoluion. Your trying to claim that this so call missing link or missing common ancestor had all of these traits and then for some reason distributed them all out to the different species?

John, please tell us specifically how this falsifies the theory of evolution.

(not that I give any credit to John for actually stating accurately what is being said here, I just think it is funny everytime he uses the word 'falsify' in a way that has no basis in reality)

 

[mikeynov]

I hope you realize that you just falsified the theory of evoluion. Your trying to claim that this so call missing link or missing common ancestor had all of these traits and then for some reason distributed them all out to the different species?

I'm not sure what you're saying, and I'm also pretty sure that you're not sure either.

Regardless, nothing you said here actually makes sense. Reread the original post.

 

[mikeynov]

John, please tell us specifically how this falsifies the theory of evolution.

(not that I give any credit to John for actually stating accurately what is being said here, I just think it is funny everytime he uses the word 'falsify' in a way that has no basis in reality)

Interestingly, rereading John's post, I think I see what the problem is:

He really, sincerely doesn't understand evolution. I think he's glossed over any explanation ever offered of what the term "nested hierarchy" refers to, and still has this idea of evolution in his head:

Fish -> Amphibians -> Reptiles -> Mammals --> Us

I.e. the linear, pre-Darwinian model that so many creationists seem to think represents evolution.

At least, that's my interpretation of his confusion.

 

[Aron-Ra]

I must admit there is an error in the OP, and the error is mine. Sorry, I guess I wasn't really paying attention. Teleostomi should be replaced with Osteichthyes

I know I know. I should be flogged with a herring at dawn.

 

[Aron-Ra]

Interestingly, rereading John's post, I think I see what the problem is:

He really, sincerely doesn't understand evolution. I think he's glossed over any explanation ever offered of what the term "nested hierarchy" refers to, and still has this idea of evolution in his head:

Fish -> Amphibians -> Reptiles -> Mammals --> Us

I.e. the linear, pre-Darwinian model that so many creationists seem to think represents evolution.

At least, that's my interpretation of his confusion.

Maybe if I drew him a picture?

 

[mikeynov]

I must admit there is an error in the OP, and the error is mine. Sorry, I guess I wasn't really paying attention. Teleostomi should be replaced with Osteichthyes

I know I know. I should be flogged with a herring at dawn.

Fixed.

 

[Lucretius]

Aron, we won't flog you with a herring, but you must cut down the tallest tree in the forest with a herring…

then you must find me a srubbery…

Then… another shrubbery, though make it a bit smaller so we get the two level effect, sort of like a path you know…

 

[alivenchrist]

I would like to know how you believe that the universe was created?

 

[mikeynov]

I would like to know how you believe that the universe was created?

Magic, obviously.

 

[Aron-Ra]

I would like to know how you believe that the universe was created?

When I still held spiritual beliefs, I leaned toward the Tao, and its collision of light and dark forces, the result of which caused the eruption of the cosmos.

Obviously that same concept greatly impressed George Lucas as well. But its not a bad explanation when you consider that it was written some 1,600 years ago in an Asian country far far away.

The strange thing is, String Theorists are now proposing a very similar origin of all things. Perhaps Lao Tsu was onto something?

May the Tao be with you.

 

[MidnightBlue]

Having evolved from sarcopterygi doesn't mean that we are sarcopterygi. Very cute, though. I enjoyed it.

 

[mikeynov]

Having evolved from sarcopterygi doesn't mean that we are sarcopterygi. Very cute, though. I enjoyed it.

If sarcopytergians represent a monophyletic clade, then sure it does.