Suggested Video: Taxonomic Classification Systems (More interesting than it sounds)

I posted this somewhere else, but am reposting it here because there wasn't much traffic where I posted it the first time.

I think SciShow should do a video comparing and contrasting Linnaean taxonomy and Phylogenetics.

The short of it is that originally, Linnaeus assigned each living things into 7 layers of classification. Phylum, class, order, family, genus and species. It soon became clear that 7 was not nearly enough ranks, taxonomists just kept adding layers, such as super-order, infra-order etc. Eventually it became clear that there are no ranks in nature, so they threw out the ranks all together and created a system which uses an arbitrary number of divisions called Phylogenetics. The divisions in phylogenetics occur when a lineage of organisms diverged into separate species, making it far superior to Linnaeus' method of assigning groups into arbitrary layers. 

There are some extremely common misconceptions about the nature of evolution taxonomy that arise from the use of Linnaean taxonomy. One such misconception is that, addressed on SciShow before, is that birds are not dinosaurs. In fact, they are, because birds have a direct ancestor that certainly is a dinosaur. In the same way, humans certainly are both apes and monkeys. Not only do we fit all of the required morphological characteristics, we also share direct ancestors that are definitely apes and ancestors that are definitely monkeys.

So yeah. Some rich material there. What do you think? Are there any other topics that you think would be important to cover?

Comments

  • AaronAaron Dundee, U.K.Posts: 757 ✭✭✭✭✭
    edited November 2012
    Hank already covers taxonomy in some depth on Crash Course Biology. But I know almost nothing about this area outside of Crash Course, so maybe what you're proposing is something beyond what's done in Crash Course. I do find taxonomy fascinating, partly because it describes the course of evolution even though the system of classification was created so many years before Darwin.
    by Aaron
    Elusive of the Last Ones
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  • KruglordKruglord Posts: 10
    Aaron said:
    Hank already covers taxonomy in some depth on Crash Course Biology. But I know almost nothing about this area outside of Crash Course, so maybe what you're proposing is something beyond what's done in Crash Course. I do find taxonomy fascinating, partly because it describes the course of evolution even though the system of classification was created so many years before Darwin.
    Yes, you're right. Hank did do an episode of Crash Course on Taxonomy.


    Hank talks about Carl Linnaeus during the biolography, and mentions that there are faults in the system of classification that he created but doesn't mention what those faults are (besides mentioning the addition of the domain). Not that I think Hank did a bad job (I think that Hank did a wonderful job given the time constraints of the video), but I think that the limitations of Linnaean Taxonomy are both interesting and important. That is, interesting and important to me, but maybe this is just an other esoteric topic that only I find interesting :P
  • OlleOlle Posts: 289 ✭✭✭
    edited May 2013
    Excellent suggestion for a topic; I happen to be a systematics geek myself. =D

    I would contest your choice of words to some degree. Phylogenetics as such isn't necessarily at odds with traditional taxonomy; they can coexist. Linnaean ranks are still perfectly useful so long as you recognize that they're arbitrary, and are prepared to do a lot of rearranging of the tree of life whenever new evidence comes up. The difference, as you rightly point out, is that phylogenetics assumes that systematic groups should reflect evolution, whereas taxonomy pre-Darwin simply assumed that they should reflect some sort of natural order put there by God.

    Whether or not birds are to be considered dinosaurs depends on whether you apply cladistics (or cladism), which only accepts monophyletic groupings (i.e. ones that include a common ancestor and all of its descendants, excluding none). Since dinosaurs included the ancestors of birds, the term "dinosaur" includes birds under cladistics. I think cladistics is useful to a point; it's helpful to know what's monophyletic and what isn't, but the regime becomes a bit oppressive if we can never use perfectly understandable paraphyletic terms like "tree" or even "fish". =P

    Until SciShow picks up the subject, you might enjoy a video I made about it:
    by Olle
    Stuff I make: webcomic (weekly); biology vlogs (every few months); tumblr posts (apparently)
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