by Chet Raymo
by Chet Raymo
“When his friend James Madison's betrothed broke off their engagement, Thomas Jefferson wrote in sympathy. "Of all machines," he said, "ours is the most complex and inexplicable." Would beautiful Kitty Floyd, Madison's intended, have appreciated being called a "machine"? Would you? But, of course, Jefferson is right, we are machines. Hugely complex and still largely inexplicable biological machines, at least by the evidence of the biological papers I read weekly in the journals Science and Nature, which profusely invoke the mechanical metaphor. "Cellular machinery." "Molecular machines." "Molecular motors." "Replication mechanisms." "Mechanisms for maintenance of DNA ends." And so on.
It's the rare paper that does not invoke computer modeling for biological molecules and processes. Computers are machines. Machines helping to understand machines. Many people recoil from the mechanical metaphor for life. They cling to the notion that there is something magical, irreducible and transcendent about human life, especially, something that will forever escape the grasp of the molecular biologists with their computer models of chemical structures.
Two things to keep in mind:
1) "Life is a machine" is only a metaphor. All understanding is metaphorical -- in science, in poetry, even in theology. No one mistakes the gray-bearded man on the ceiling of the Sistine Chapel for God, but Michelangelo's powerful metaphor evokes awe and understanding of something essential to the believer's idea of God. In science, too, we use the metaphors that most fruitfully advance our understanding of nature.
2) The mechanical metaphor for life does not so much reduce the miraculous to the mundane as it elevates the mundane to the miraculous. "Mundane" comes from the Latin mundus, meaning "world." The more we understand the staggeringly complicated and apparently inexplicable molecular machinery of life, the more truly miraculous the world seems. Kitty Floyd included.”