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"Nothing in biology makes sense except in the light of evolution." - Theodosius Dobzhansky.

The word evolution has been defined as "the gradual developing of something"[1].

Some argue that evolution is strictly the change over time, in genes and proteins, that occur in a population which allow an organism to be advantageous in its surrounding environment. Organisms change continuously over time due to random mutations; however, the aforementioned definition incorporates that these changes - the evolution of a certain organism, must be beneficial in terms of its environment.

Evolutionary changes in metabolism, development and behaviour created three domains[2][3][4]:

Causes of evolution are mutation, migration, genetic drift and natural selection.

The first scientist in history that explained how evolution works and hypothesized the theory of natural selection was Charles Darwin.

Charles Darwin proposed the theory of natural selction which entails that it is the key mechanism of evolution as it is based on the change of heritable traits of a population over generations. Due to mutations and adaptions, some individuals develop characteristics that are selected for the environment and it helps them survive, whereas other individuals develop characteristics that are selected against the environment and it puts them in disadvantage. Therefore, the individuals that are selected for and are well adapted will reproduce within themselves and the poorly adapted organisms will not pass on their traits to an offspring. This results in a big sample of well-adapted population with traits that are better selected for survival over generations whereas there will be fewer and fewer individuals that are poorly adapted over a generation. From this situation, the term "survival of the fittest" was created where the strongest individuals are bound to survive and pass on their traits within a harsh environment[5].


  1. http://oxforddictionaries.com/definition/evolution
  2. Hartl, D.L. and Ruvolo, M. (2011) 'Genetics: Analysis of Genes and Genomes.' 8th edn. Burlington: Jones and Bartlett Learning.
  3. University of California Museum of Paleontology. (). Mechanisms of Change. Available: http://www.evolution.berkeley.edu.
  4. Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, Peter Walter. (2008) Molecular Biology of the Cell, 5th edition, New York: Garland Science
  5. What Is Evolution?". 2018. BBC Bitesize. Accessed December 10 2018. https://www.bbc.com/bitesize/articles/z9qs4qt.
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