The fish thing is irrelevant. If what makes bonobos and orangutans apes is that they share a common ancestor, then that also makes us an ape, since that’s our ancestor too. Can’t adapt that argument to fish, because descendants of the ancestor we share with fish are not generally called fish, the way descendants of the ancestor we share with orangutans are generally called apes.
Can’t adapt that argument to fish, because descendants of the ancestor we share with fish are not generally called fish, the way descendants of the ancestor we share with orangutans are generally called apes.
I’m not sure this holds water: a common-ancestry approach would have to take in lobe-finned fishes like the lungfish, who’re more closely related to tetrapods but are called fish on the basis of a morphological similarity derived from a common ancestor. Essentially the same process as for apes. They’re in good company, though: there are plenty of traditional taxonomical groups which turn out to be polyphyletic when you take a cladistic approach, including reptiles.
There would be no point in defining fish monophyletically anyway, as it would then be just a synonym of craniates. (Also note that “apes, i.e. non-human hominoids, do not include humans” is a tautology but “fish, i.e. non-tetrapod craniates, do not include humans” is not.)
(Of course, you could then say “There would be no point in defining apes monophyletically anyway, as it would then be just a synonym of hominoids.” But hominoids is a much uglier word, and hominoids/hominids/hominines/etc. are much harder to remember than apes/great apes/African apes/etc. (plus, my spell checker baulks at some of the former, FWIW). (See this proposal to rename the scientific names of the clades.)
I don’t see why being monophyletic is the most relevant property of definitions.
Also, are you also going to attempt to argue that humans are fish?
The fish thing is irrelevant. If what makes bonobos and orangutans apes is that they share a common ancestor, then that also makes us an ape, since that’s our ancestor too. Can’t adapt that argument to fish, because descendants of the ancestor we share with fish are not generally called fish, the way descendants of the ancestor we share with orangutans are generally called apes.
I’m not sure this holds water: a common-ancestry approach would have to take in lobe-finned fishes like the lungfish, who’re more closely related to tetrapods but are called fish on the basis of a morphological similarity derived from a common ancestor. Essentially the same process as for apes. They’re in good company, though: there are plenty of traditional taxonomical groups which turn out to be polyphyletic when you take a cladistic approach, including reptiles.
There would be no point in defining fish monophyletically anyway, as it would then be just a synonym of craniates. (Also note that “apes, i.e. non-human hominoids, do not include humans” is a tautology but “fish, i.e. non-tetrapod craniates, do not include humans” is not.)
(Of course, you could then say “There would be no point in defining apes monophyletically anyway, as it would then be just a synonym of hominoids.” But hominoids is a much uglier word, and hominoids/hominids/hominines/etc. are much harder to remember than apes/great apes/African apes/etc. (plus, my spell checker baulks at some of the former, FWIW). (See this proposal to rename the scientific names of the clades.)