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By Root 1217 0

clues to how that happened. The Internet did not suddenly appear one morning, ready to send your e-mail anywhere in the world. It began in 1969 as a crude link between computers at the University of California in Los Angeles and the Stanford Research Institute in Palo Alto, California. Other institutions joined the network over the years, and more links were added between them. The Internet became robust thanks to its overall architecture. But no one wrote down the design specifications for the entire Internet in 1969. They emerged along the way. Computer engineers focused their attention on how well each small part of the network performed. They worried about the cost of long-range connections between servers, and so they kept the links short.

E. coli’s network grew in a similar way. As genes were accidentally duplicated, the network grew more complex. Mutations rewired some of the new genes so that they interacted with other genes. Natural selection then selected the favorable mutations and rejected the rest. As efficient small-scale components evolved, a robust network emerged as a by-product.

At the Dover intelligent design trial, creationists revealed a fondness for analogies to technology. If something in E. coli or some other organism looks like a machine, then it must have been designed intelligently. Yet the term intelligent design is ultimately an unjustified pat on the back. The fact that E. coli and a man-made network show some striking similarities does not mean E. coli was produced by intelligent design. It actually means that human design is a lot less intelligent than we like to think. Instead of some grand, forward-thinking vision, we create some of our greatest inventions through slow, myopic tinkering.

FIRST WORDS

Scrape away E. coli’s new genes—the arrivistes carrying resistance to penicillin and other drugs. Peel back the older genes that E. coli evolved after splitting off from other bacteria millions of years ago. Strip off the deeper layers, the ones that build E. coli’s flagella and the ones that have been destroyed beyond use. Strip away the genes for its peptidoglycan mesh, its sensors for rewards and dangers, its filters and amplifiers. Get rid of the genes that encode the proteins that were carried by the last common ancestor of all living things some 4 billion years ago.

You are not left with a clean sheet. A scattered collection of enigmatic chunks of DNA remains. These are not typical genes. E. coli uses them only to make RNA, and that RNA is never used to make proteins. These RNA genes are the oldest level of the palimpsest. Scientists suspect that they are vestiges of some of the earliest organisms that existed on the planet, from a time before DNA.

Life’s raw materials are no different from lifeless matter. Stars made the carbon, phosphorus, and other elements in our bodies. If you travel the solar system, you will encounter meteorites and comets with ample supplies of amino acids, formaldehyde, and other compounds found in living things. The Earth incorporated many of these molecules as it formed 4.5 billion years ago, and showers of space dust and the occasional impact of a bigger hunk of rock or ice brought in fresh supplies. The planet acted like a chemical reactor, baking, mixing, and percolating these molecules, probably producing still more molecules essential to life before life yet existed. The great mystery that attracts many scientists is how this reactor gave rise to life as we know it, complete with information-encoding DNA, its single-stranded counterpart RNA, and proteins.

As soon as the basic outlines of molecular biology became clear in the 1960s, scientists decided that DNA, RNA, and proteins did not emerge from the lifeless Earth all at once. But which came first? DNA may be a marvelous repository of information, but without the care provided by proteins and RNA it is just a peculiar string-shaped molecule. Proteins are awesomely versatile, able to snatch atoms drifting by, forge new molecules, and break old ones apart. But they are not so good at storing information