Evolution generally refers to any process of gradual or incremental change over time. In the context of biology and life science, biological evolution is one of the most basic laws which describes a change in the genetic makeup of a population as a result of natural selection. It is the process by which all forms of plant and animal life change slowly over time because of slight variations in the genes that one generation passes down to the next.
Laws (esp. the differential equations from physics) describe the time-evolution of nature: the gradual or incremental change over time. Evolution itself is therefore the most general law, because it can also be applied to cosmic, economic, biological and social systems. In fact, evolution itself is the only thing in the last 14,6 billion years since the universe exist which has not changed significantly.
Evolution can occur in any changing system, as long as there is a code and the following three conditions are satisfied: (1) variation among individuals in some property or trait (2) inheritance from parents to their offspring of these traits (3) competition between individuals, selection of the individuals where the traits have the best effect on fitness and survival ability.
Thus the three major principles of evolution are
- Variation (Modification, Recombination)
- Inheritance (Descent, Replication)
- Natural Selection (Survival of the Fittest)
Evolution means descent with modifications, or inheritance with variation. It requires 1.) a source of variation and diversity in form of recombination or mutation 2.) a source of continuity in form of replication or reproduction, and 3.) a source of purpose or function through selective pressure in form of natural selection, adaptation or "survival of the fittest". Natural selection results in a process of adaptation. Speciation is the evolutionary process by which new biological species arise.
The principle of evolutionary relationship means related species have evolved from a common ancestor, and new species always come from pre-existing species. Taken to the extreme, this means every organic being evolved from a common ancestor. Charles Darwin proposed the theory of universal common descent through an evolutionary process in his book "On the Origin of Species", saying, "Therefore I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed".
Biologically inspired Evolutionary Algorithms are a popular approach to optimize structures and to search for solutions of difficult combinatorial problems. Peter J. Bentley from the University College, London, has even proposed "software genes" to create useful evolving and developing software, see his New Scientist article The Garden where perfect software grows.
Charles Darwin - On the Origin of Species
- Origin of Species, 1st edn. (1859) (British Library)
- Origin of Species, 6th edn. (1872) (British Library)
- Full text in pdf format
- Origin of Species, 1st Edition (Project Gutenberg)
- Origin of Species, 6th Edition (Project Gutenberg)
- Origin of Species (Vol. XI. The Harvard Classics. New York: P.F. Collier & Son, 1909–14; Bartleby.com, 2001)