Evolutionary pressure is the force with which evolution directs the development of species. In this case, ‘directs’ is a deceiving word, since the process is blind.

While evolution is blind, it is not random. Evolution favors organisms that survive and replicate themselves. Obviously, this creates an evolutionary pressure towards creatures that can sustain life and replicate it. Consequently, all plants and animals spend a great deal of their time maintaining their lives and producing new ones. Evolution does not ‘prefer’ organisms who reproduce, but organisms who reproduce will become more common, through their reproduction.

In giving evolution a name, many people have taken on the confused belief that it is a directed force. In actuality, it is the simple tendency of stable molecules to remain longer than unstable ones. We see very few isotopes of hydrogen with ten-thousand neutrons, while most of the universe is composed of hydrogen lacking any neutrons.

Any molecule that can produce copies of itself has an incredible advantage, in terms of the size of its population. While most complex molecules form randomly, and thus rarely, if a molecule can actively assemble a copy of itself it will be far more common. It does not, as a molecule, ‘want’ to replicate itself anymore than evolution as a force ‘wants’ to produce life. These things merely happen as a consequence of the physical properties of the universe.

Thus, stable molecules will eventually and randomly become prevalent and one of those random alterations will produce a molecule that can replicate itself: basically a crystal. Then, given the fundamental principle that stable, reproducing molecules become more common, life as we understand it has developed. To go into the specifics of how this occurs is far beyond the reasonable content of this entry, but expressed with remarkable clarity and reason in Richard Dawkin’s book: The Selfish Gene.

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