Few people have ever been convinced they had found the Secret of Life. And those who were convinced of it have often not remained so for very long. Robert Brown (1773-1858), for example, thought he had found it when he observed pollen grains in water under a microscope and saw them moving independently of each other. He interpreted it as evidence of an indivisible unit of life, capable of forming new flowers. It later emerged that any inorganic matter can show the same sort of random motion, now termed Brownian motion.
Francis Crick (1916-2004) announced in 1953, together with James Watson (1928-), that he had found the secret. He was referring to the structure of DNA, the landmark discovery with which his name will always be connected. Many people erroneously credit him for something else also: the discovery of the genetic code. In fact, it was the brilliant physicist George Gamow (1904-1968) who was first to realise that the four-base variations of the DNA molecule constitute a code.
But are we there yet?
Any living organism, even the simplest bacterium, performs innumerable complex activities that cannot possibly be deduced from the genetic sequence alone. We have found the main repository of information, but we are still fumbling in the dark when it comes to the principles for deciding what information to read, and when, and why.
Even the simplest units of life exhibit extremely robust and well-regulated behavior. A protozoan looking for food decides to go in one direction, and not the other. A cell of a slime mold decides to sacrifice itself for the greater good of the community. These actions are governed by a vast network of interconnecting signaling mediators, most of them proteins.
Scientists working on these networks have, for the most part, a mental model of the cell resembling a machine composed of cog-wheels. Endless hours are spent trying to find out which wheel grabs on to which. Huge tabulations are made with arrows indicating either stimulation or inhibition of one protein on another.
These models are drawn in the face of our massive understanding that biological systems tend to be non-linear and dynamic. If I poke the system gently and upset one of the signaling molecules, it is for the most part impossible to tell what changes will follow in the complex system.
At the same time, this very complexity gives rise to new phenomena on a system level. Robustness and stability towards certain stimuli are coupled with remarkable adaptability to others. Higher-order conformity to laws of behavior appear.
The biological system takes information and creates meaning. We do not know how.
This is the next frontier, and possibly the final one, in our quest for the secret of life.