Theories related to life’s creation and its evolution are still being proposed. In the 1960’s Francis Crick, Leslie Orgel and Carl Woese independently proposed that RNA preceded proteins in evolution, and introduced the idea of an early “RNA world.” In 1983, Thomas Cech and Sidney Altman found evidence that RNA can act as a catalyst, so supporting the RNA world theory.
Current thinking posits that early RNA exchanges occurred laterally (within a commune of different cells), rather than generationally (from parents to offspring), as DNA now replicates. The former may have facilitated many primitive evolutionary developments, and has been found to occur in bacteria.
An alternative theory, put forward by Graham Cairns-Smith, suggests that an inorganic genetic system is likely to have existed before the RNA world, possibly one involving the irregular distribution of cations since found in clays.
Ideas and findings such as these may help us to replicate possible early life forms in the laboratory. That we will create life from scratch one day is not much doubted by any biologist (although some prefer that we never make the attempt). However, the methodology we use to succeed may not be the way that life started (on this planet or elsewhere in the universe), because there are likely to be many ways that life could begin. We will probably use water as its basic ingredient, and we already know the other elements and molecules from which Earthly life is constructed. However, it is not a matter of which ingredients to use, the problem is how to assemble these to form a self-contained processing system.
A web search for articles relating to the creation of life or the discovery of extraterrestrial life forms will yield many other interesting details. Life And Exploiting adds a further note to this discussion of life’s beginning.
- The ribonucleotides in RNA are more readily synthesized than the more complicated deoxyribonucleotides in DNA. Most importantly, RNA can replicate and store genetic information.
- Water is plentiful throughout space, but any fluid could be used because fluids readily transport energy-providing resources and molecules from place to place. Gases (and high temperature plasmas) are fluids, and life may have originated in such environments.