The tree of life.

Yesterday we spent some time on animal classification. I bought a few decks of animal flash cards from the dollar bins at Target, gave each kid a large pile, and asked them to sort them however they pleased. Colin decided to sort his by picture vs. landscape orientation. Alex made several piles: mammals, reptiles, insects, gross ones, ones with feathers, and ones that live in the ocean.

While they were sorting, I collected some of our various picture books about animals. We glanced through them and talked about how each one sorts the animals: by habitat, by descriptor, by color. Different sorting schemes have their own advantages, depending on the purpose of sorting. Just for fun, we also looked at the Jorge Luis Borges passage about

a certain Chinese dictionary entitled The Celestial Emporium of Benevolent Knowledge. In its remote pages it is written that animals can be divided into (a) those belonging to the Emperor, (b) those that are embalmed, (c) those that are tame, (d) pigs, (e) sirens, (f) imaginary animals, (g) wild dogs, (h) those included in this classification, (i) those that are crazy-acting (j), those that are uncountable (k) those painted with the finest brush made of camel hair, (l) miscellaneous, (m) those which have just broken a vase, and (n) those which, from a distance, look like flies.

Then I introduced Linneus and the idea of the phylogenetic tree of life. We looked at some beautiful images that give some idea of the complexity of life and the relationships between species. I also drew a very simple diagram showing how animals can be divided into vertebrates and invertebrates, and then how vertebrates (well, okay, chordates) can be further divided into bony fishes, sharks and rays, reptiles, amphibians, birds, and mammals. I also listed some of the major classes under amphibians, reptiles, and mammals, and carried the “primates” branch down to humans. Alex was very interested and seemed to grasp the basic ideas well.

We took her flash card piles and re-sorted them into vertebrates and invertebrates. We subdivided the vertebrates into separate phyla, and then – with greater difficulty – attempted to sort out the different classes of mammals. The flash cards didn’t have the full Linnean taxonomy on the back, which made that a lot harder. (Where does a hippo fit? A peccary? An anteater?)

We talked briefly about the idea that Linnean categories are being replaced as scientists develop a better understanding of genetic relationships among species, but I didn’t dwell on it at all. Alex has only the haziest idea of what a gene is, at her age. She is showing persistent interest in the tree of life, though. We spent more time browsing web images this evening, and she asked if we could make our own. I’d love to get this incredible poster for our wall.

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2 Responses to The tree of life.

  1. Kim says:

    Omg now I really want a couple sets of those cards!!! And of course I’m traveling and won’t be near target for over a week! Lol. They’ve had them for ages; I’ll just have to hope for the best! Neat lesson!!

  2. Julie says:

    Pinteresting this for our upcoming science lesson on classification. Thanks!

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