Friday, May 09, 2008

At the pond

Where the Queset Brook passes under the plank bridge along my Path, it slows and purls into a broad pond. This was called "The Girl's Swimming Hole" when it was part of the estate of Oliver and Elise Ames. The pond is no longer deep enough for swimming, but on these fine May afternoons I will sit there for an hour on my way home from college, reading, thinking, doing nothing.

And watching the surface of the pond come alive with the flit and skitter of a new season.

Water striders scull and stop, scull and stop, and now and then do an energetic back flip, in their search for morsels; the indentations of their feet and antennae on the surface of the water show up on the sunlit bottom of the pond as six fat blobs of shadow. Whirligigs spin like tops, like whirling dervishes, black as night in the afternoon sun. Mayflies enjoy their ephemeral fling as adults, their aerial orgy like snowflakes whirling above the dark water. Dragonflies and damselflies patrol the weedy margins of the pond, their bodies iridescent. Now and then a tree swallow from the boxes in the meadow makes a low, lightning-fast devouring sweep just millimeters above the surface of the water.

My mind drifts back to the new phylogenomic tree of life that was published in Nature a few weeks ago, 77 species across 21 phyla. I don't have to go back too many steps on the phylogram to connect myself to all the creatures I am watching at the pond. Our common ancestral group is the bilateria, animals that are bilaterally symmetric, with a front end and a back end, an upside and downside, a mouth and an anus. The first of our tribe appears in the fossil record about 600 million years ago, and it turned out to be an effective body plan. Of course, we bilateria don't exhaust the ranks of life on Earth, but we make up a goodly part of the phylogram. Anyway, I sit at the bridge and I feel part of something a lot bigger than myself -- something with a front end and a back end, an upside and downside, a mouth and an anus. The swallow zips across the pond; I give her a wink. She and I have our own little niche in the phylogram. We have backbones.

Humans have a way of drifting through the world as if we were temporary visitors from another dimension. A few moments at the bridge remind me that we are bound to the rest of creation by a myriad of genomic threads.