Nature Notes: Sentenced to Symmetry
Circles and squares, rectangles and cones, triangles and cylinders, octagons, pentagons, spheres and so on. We are surrounded by symmetry, and why not? The earth is spheroid, the moon and the planets are round, and so, it seems from our perspective, is our sun. According to the conjectures of some astronomers and astrophysicists the universe is circular.
We humans are bilaterally symmetrical. Our pets are also bilaterally symmetrical. Our livestock are bilaterally symmetrical. Most of us live in symmetrical square or rectangular houses. Architects have been fighting the constraints of symmetry for centuries, but no matter how hard they try to get beyond its bounds, symmetry often wins out.
Plants apparently stem from symmetrical ancestors. The first bacteria, blue-green algae, viruses, and other proto life forms were symmetrical. Conifers, especially the spruces, firs, hemlocks, and larches are conically symmetrical just as their cones are. The Hollywood juniper so widely planted now on the South Fork and elsewhere is the epitome of a perfectly conical evergreen. It has become the model. The oak tree that grows tall in your yard looks to be asymmetrical, but if you examine it carefully, you will find out that the canopy’s edges, the so-called drip zone, unite to form a crude circle. The roots that spread out radially and often reach to the canopy’s perimeter also are distributed in a roughly circular fashion.
Take the fruit of trees — the walnuts, the oranges, apples, and even acorns are round or roundish. There is no such thing as a square or rectangular fruit. The walnut hits the ground running, acorns roll downhill when freed from their cup. Maple fruits are an exception; they are bilaterally symmetrical samaras. But when they fall from their trees they rotate like the blades of a helicopter and this rotation can carry them a good distance away from their parents.
The largest and most advanced group of flowering plants, the sunflowers, are almost 100-percent radially symmetrical. While the flowers are disc shape, the seeds, or achenes, with their tufts of hairs, or pappi, waiting to waft them away in the slightest breeze, are frequently clustered in a perfect sphere at the top of the stem as in the common dandelion.
In the marine environment there are entire classes of organisms that exhibit radial symmetry. Starfishes, jellyfish, sea anemones (seen from above) and many phytoplankton species are radially symmetrical. A few fish, like the northern puffer, or bottlefish, can mimic radial symmetry when defending themselves against a predator. They blow up! But most fish tend to be fast swimmers. You can’t be globular and move swiftly through the water.
A few fish, the eels for example, are roughly cylindrical. They are fast swimmers and resort to other means to get away from predators. Snakes are quite cylindrical and legless. Long cigar-shaped cylinders, eels, snakes, earthworms, and the like move sinistrally, they slither in semicircles. In the snakes, the “racers” have such locomotion down to a fine art. They can almost move as swiftly as a human can run. The sidewinder, a rattlesnake of the Southwestern American deserts, has perfected such side-to-side locomotion and can even move rapidly in fine grain sands where it is hard to get a firm purchase. The poisonous sea snakes of the Pacific regions swim sinusoidally like the eels, to which they are not at all related.
There is a TV detective, Monk, who is so tied to symmetry that he exhibits a kind of phobia, “asymmetriphobia.” But he’s a very good detective aside from that. In military barracks, there’s a high degree of symmetry. With the exception of the circular commodes, everything else is rectangular — cots, foot lockers, and the like. The only roundish objects seen are the toes of military boots and perhaps infantry helmets.
Soldiers, like the members of marching bands, move in perfect rectangular lines down rectilinear streets. Tanks and armored vehicles move in the same formations. In the case of marching bands, the people who stand on either side of the street form long parallel lines. The buildings that back them do the same.
Symmetry is a form of very high order. Too little symmetry and you have dystrophy or chaos, which in its most extreme form is nothing less than what the German physicist Rudolph Clausius termed “entropy” in the middle of the 19th century. A very messy room or “sty” borders on entropy. Unless you live in it and are accustomed to it as I am, coming across it unexpectedly can be revolting. Nature abhors a vacuum; humans abhor a very messy room. Like almost all of earth’s other millions of different organisms, in the final analysis we humans are doomed to live out our lives symmetrically. Accept it.
Larry Penny can be reached via email at [email protected].