The term evolution is commonly used to describe a number of things, usually involving a gradual process of development, formation, or growth. The word has a connotation of leading to a more advanced or complex form in many cases, although this is not the case for biological evolution.
In biology, the process of evolution is the change in a population's genetic structure over successive generations. Specifically, it is the change in allele frequency over time. The many sub-processes of evolution account for the diversity of life, such as genetic inheritance, which accounts for the continuity of traits, mutation, which accounts for novel traits, and natural selection, which accounts for the environmental filtering of traits.
A scientific model, or theory, explaining this process is called a theory of evolution (ToE). The current widely-accepted theory of evolution is the modern evolutionary synthesis, also called the Neo-Darwinian theory. Sometimes, the theory of evolution is simply shortened to "evolution" (as in, "Evolution explains the diversity of life"). Richard Dawkins also contributed with the theory of gene selection.
Ceationists often use the word evolution as though it were an exclusively historical phenomenon, referring only to the origin and past development of species over the course of geologic time. This contradicts scientific use of evolution, and roughly corresponds to the general idea of Darwinian origins. It is variously described as referring to the more specific theories of common descent, natural selection or macroevolution (though macroevolution and natural selection have been directly observed in modern field and lab studies).
However, creationists also frequently apply the word evolution to phenomena outside the scope of evolutionary biology, such as abiogenesis, the Big Bang, and general chemical and galactic evolution. Sometimes, no distinction at all is drawn by creationists between biological and non-biological evolution.
Confusion regarding the definition of evolution is made worse when the media repeats the mistakes of creationists (such as saying humans descended from apes or monkeys). This perpetuates the misunderstanding among laypeople. Humans descend from apes, not monkeys. Dictionary definitions also often add to the confusion; even older editions of the Oxford Scientific Dictionary and Scientific American give ambiguous or erroneous definitions of evolution. Definitions in many dictionaries have been corrected in recent years, but the damage has already been done to public understanding.
Chemical evolution can refer either to the theory of the development of the chemical elements through nucleosynthesis in stars, or to the theory of the development of life from non-life through chemosynthesis (see abiogenesis). Both theories are considered well-supported by modern scientists, although there is significant disagreement regarding the specifics of abiogenesis.
Galactic and stellar evolution is the development of galaxies and stars is often described as "evolution".
Sociocultural evolution encompasses many different theories describing the development of societies and cultures over time, including memetics, linguistic evolution, and technological evolution (see also Wiki evolution).
Links & Resources
- Talk.Origins: What is Evolution?
- Introduction to Evolutionary Biology
- Five Major Misconceptions about Evolution
- Talk.Origins: Evolution is a Fact & Theory
- Teaching Evolution in School Science Classes
- The Story of Human Evolution
- Understanding Evolution
- Understanding Evolution: History, Theory, Evidence, and Implications Deals heavily with the history of evolutionary thought
- Evolution by Natural Selection - An outline of the chain of reasoning behind the theory of evolution by natural selection.