Although compounds of carbon, oxygen and hydrogen can be found in the large molecular clouds that are the nurseries for solar systems, it is a long, long journey from them to even the simplest kinds of life. The simple bacterium is thought to be one of the first stages of life on earth, but inside each one are thousands of intricately interacting complex molecules. Each of these molecules, many of them proteins, may consist of literally thousands of atoms, precisely arranged.
Several properties of life are described:
- having a boundary,
- having internal processes that construct and maintain the organism,
- having the ability to respond to its environment,
- having the ability to reproduce itself.
Each of these processes requires complex, reliable molecular machinery in even the simplest bacterium.
Life may have come to our planet in spores of life from another system, but even on a different planet the first steps would still need to be explained. Current theories see life originating either in a shallow pool of water at the edge of the ocean, or at the bottom of the ocean.
A shallow pool at the water’s edge is thought to have been able to generate complex carbon compounds in response to lightning strikes. A landmark experiment in the 1950s showed the generation of even amino acids in such a circumstance.
The rock/water boundary at the bottom of the ocean has the properties of a chemical battery because basalt is actually unstable when it moves from the intense heat and pressure of the mantle. This makes the rock constantly degrading chemically in response to the mild acidity of ocean water. This provides a continual, steady source of the very kind of energy that powers all of life today. This boundary at the ocean bottom produces “white smokers” where warmer, chemically basic water is continually meeting the cooler, chemically acidic water of the ocean. Complex organic chemicals can be generated here all by themselves.
Even with such promising circumstances, the journey to the simple bacterium is still an unfathomably complex journey. Most life is constructed of proteins, which consists of very long strings of only 20 amino acids in specific sequences. It has been calculated that a string of 100 of these amino acids could be put together in 20 to the 100th different combinations. This number of possibilities is greatly larger than the number of atoms in the known universe. Time and chance are usually used to explain the progress that evolution, but the probability of life’s specific set of proteins arising from this set of possibilities is many times less probable than finding one grain of sand in the entire Sahara Desert. Crossing this and other deserts on the road to life requires big help. It comes in the form of cooperation.