Originally published 29 July 2003
There is no more delicious meal than a mess of saltwater mussels steamed in white wine, accompanied by a stick of just-baked French bread and a crisp green salad. And, of course, a carafe of chilled white wine.
Invariably, about halfway through dinner (and halfway through the carafe of wine), I begin to ponder the unfathomable mysteries of existence. Such as: How does one half of a mussel shell know what the other half is doing?
No kidding. These things bother me. Hold an empty mussel shell between your fingers. Squeeze it shut and the two sides meet like the case of a fine Swiss pocket watch. You couldn’t slip a hair between the gap. As the shell grows, adding rings like a tree, the two sides maintain intimate and precise contact, yet they are physically separate. Somehow the two sides communicate across the gap: “I’m adding a molecule at position X. You better add one, too.”
To build a mature mussel shell means putting, say, 50 billion trillion molecules into place (that’s about the number of letters in 250 trillion sets of the Encyclopedia Britannica). Symmetrically. So that the two sides of the shell stay perfectly matched.
I’m sure some scientist has thought about this, maybe even figured it out, but, if so, I don’t know about it. All I know is that darn little mussel manages to express its genes in such a way that it builds a shell that closes snugger than the door of a new Ferrari.
But why stop with mussels. Look at that lady across the table, nibbling on her salad. The lashes on her right and left eyes are exactly equal in length. How do the lashes on the left know what the lashes on the right are doing? No possibility of communication. It’s clearly genetic.
Every cell of every lash share the same set of construction plans, including the length of eyelashes, copied over and over zillions of times from the first fusion of egg and sperm. How do the genes copy themselves so flawlessly? They don’t, of course. The copying is hardly ever perfect. But every cell has chemical machinery (made by the genes) that check and repair mistakes. Built-in quality control.
Somehow, in ways we don’t yet fully understand, a four-letter chemical code spins out a body that is perfectly symmetrical. Except where it isn’t. As, for example, in the lopsided placement of the heart and the curlicue twist of the intestines.
About now you are thinking: “Ah, I wouldn’t want to go out to dinner with him.” And you’d probably be right. But there still remains the quotidian mystery of the world.
Have another glass of wine and think about snowflakes for a minute.
Snowflakes grow with a perfect six-sided symmetry, no two flakes alike. No building plan. No check and repair. Water molecules begin to crystallize around a microscopic speck of dust. The snowflake grows, adding water molecules around the edges, billions of billions of water molecules. The basic six-fold symmetry of the crystal is easily explained by the shape of water molecules, which link to form hexagons. But how do the molecules attaching at one point of the snowflake know what the molecules are doing on another point, a billion molecules away? How is the detailed, overall symmetry maintained?
I read somewhere that sublimely sensitive molecular vibrations have something to do with it, like an orchestra staying in tune. Maybe so, but imagine an orchestra that fills the entire continental United States. What are the chances that they’ll play in harmony across thousands of miles? Not very good, I reckon.
Some folks on the fringes of science talk about “morphic resonance,” by which organisms and crystals somehow “remember” what they are supposed to be from the previous experience of their kind. Hundreds of years ago Johannes Kepler proposed a “facultas formatrix” of nature, a formative faculty, to explain the symmetry of the snowflake. OK, but giving something a name doesn’t explain it.
The funny thing is, the more we learn about the world the more astonishing the whole thing seems.
Now take this lettuce leaf, for instance…
