DNA Science Challenges Sweden's Famed Botanist

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Swedish physician and botanist Carl Linnaeus was the founder of the modern system of binomial nomenclature for plants.

Enlarge Adeline Goss

This earthworm-like creature at the National Museum of Natural History is a lizard.

Adeline Goss

This earthworm-like creature at the National Museum of Natural History is a lizard.

This month marks the 300th birthday of Carl Linnaeus, Sweden's beloved botanist who gave order to the plant and animal kingdoms.

The Swedes will celebrate on Wednesday with a jubilee in Uppsala, complete with Linnaeus cream cakes.

Why all the fuss? Linnaeus created the words that describe the living world. "Homo sapiens," for example, is a Linnaeus "binomial" to describe humans. The botanist and his disciples traveled the world collecting species, naming them, and organizing them.

Linnaeus' organizing principle — called ranking — is alive today in every high school biology classroom, where students learn mnemonics for ranking living beings: kingdom, phylum, class, order, family, genus and species. Within these ranks, organisms are lumped together by common traits.

But modern science is complicating Linnaeus' ranking system. DNA analysis often shows that two organisms, thought to be distant relatives, are actually first cousins. There are now sub-orders, super-orders, even "tribes."

Kevin de Queiroz, curator of the reptile and amphibian collection at the National Museum of Natural History in Washington, D.C., says that the most recent example in his collection is something nicknamed a "worm lizard."

With no arms and no legs, the lizards, called Amphisbaenia, look like bloated earthworms. Their name comes from Amphisbaena, a mythical serpent with a head at each end. De Queiroz didn't know which shelf to put them on until recently, when DNA analysis showed they were related to some of the most common lizards in Europe.

These changes have made the evolutionary "tree" somewhat messy. Some taxonomists are moving away from the ranking system, and instead organizing species strictly by how they evolved. Others, faithful to Linnaeus, say the ranks make taxonomy easier to understand.