caffeine writes:
None of this is of any relevance, though. Domain, class, family and all the other taxanomic levels are purely arbitrary human inventions. They have no existence in the external world. They are far less clearly defined than the concept of 'kind'.
I don't know about that. I think that the current version of the Linnean taxonomy system is possibly arbitrary in an
absolute sense. There's debate all the time about whether two populations have speciated, or whether a cluster of genuses currently in one family would be better described as belonging to two different families. (Please, someone with a better understanding of biology should step in if I'm saying something particularly stupid.) But, I think that the system is still highly useful in illustrating
relationships among populations. There's no doubt in my mind that the grouping of populations of organisms into a nested hierarchy is accurate as far as the big picture goes, and a strong demonstration of the truth of common ancestry. Probably cladistics does an even better job of showing relationships over time, but I don't know enough to say.
One question occurred to me as I was putting this little quiz together. Can we say that the degree of difference between members of subgroups in one larger group is the same as the degree of difference among the members of subgroups in a larger group at the same level? An example will probably make my question clearer.
Start with the class Mammalia. Pick two orders within that class, say rodents and primates. Do all the families within one order (e.g. the mouse family and the mole rat family in the rodent order) show the same degree of difference as all the families within the other order (e.g. the great ape family and and the lesser ape, i.e. gibbon family in the primate order)? Would that imply an absolute classification system?
I hope that this makes some amount of sense.
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