The Tree of Life

The slide showed a dirt road enveloped in a misty shroud. At the side of the road a beautiful red flower with a yellow lip stood out against the wet green blades of grass. Pebbles glistened. “What is it?” I asked Ryan. “A weed,” he replied.

I am not very good at remembering the names of plants and animals, but many of my friends take pride in their familiarity with the biota of home and beyond. There is a branch of biology involved in the naming and identification of organisms, taxonomy; implicit to this discipline is the field of systematics, the classification of organisms. Biological classification is hierarchical—species are grouped into genera, which, in turn, are grouped into families, and so on. Theoretically, at the end of the search for the natural order is the one tree of life.

For six years I worked in a systematics lab as a technician. I did not become as well versed in the field as did the graduate students around me, but I did acquire a basic vocabulary. The words are long and their meanings complex, but a few words provide a basic orientation. Plesiomorphies are characters, or qualities, that species inherit from their primitive ancestors; synapomorphies are new, unique characters that two or more species may share. It is synapomorphies that establish relatedness among groups.

Biologists come to their disciplines with different motivations, and, as most of us are influenced by the work we do, they take from their disciplines perceptions about the world. Being an organized type, I found the promise of a natural order alluring. However, systematics is not only about existing patterns but about how they came to be—in other words, historical lineages.

Ryan told me excitedly one day that he had learned that his mother’s family had been in the United States since the seventeenth century and had been an original Maryland family, receiving extensive land grants. His family could trace its roots to some great Norman ruler. “Of course every family has its distribution of kings and scoundrels,” he quipped. “Your name is probably polyphyletic”—a term for species having similar characters but derived from different lineages. “Names that refer to trades usually are.” We returned to our work, each pursuing his piece of the tree—Ryan writing his tome on a group of beetles, I measuring the length of moth legs.

Gracile dendritic arms merge to form a heavier limb, which, in turn, joins with other branches to form a stout bough, and so on—until the trunk of the tree of life finds root in Mother Earth. Indeed, there may be one tree of life. From it we can learn about evolution and relatedness; from it we can learn about chance and circumstance. New buds, new limbs, old limbs, full limbs, sparse limbs, dead limbs—but not better limbs.

I am a weed that grew in Brooklyn. I delight in our plesiomorphies.

 

Originally published in Tiny Lights: A Journal of Personal Narrative

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5 Responses to The Tree of Life

  1. preid16 says:

    Like this a lot.

  2. Very poetic. So is there a connection between “polyphylitic” and “weed”? And are you the red flower with the yellow lip?

  3. Neither. The appellation of weed is a relative concept. 🙂

    • I woke up thinking of my response and realized I must have been asleep when I wrote it. 🙂 In a “nonscientific” sense, the term weed could be perceived as polyphyletic. Good call!

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