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What is a Mutation?


Pop culture really loves mutations. We see movies about the Teenage Mutant Ninja Turtles with superpowers or mutated monsters that escape from science labs to wreak havoc on the community. 


In the scientific sense, a mutation is a change in the nucleotide sequence of an organism’s genetic code. This can occur naturally due to errors in DNA copying, or it can be induced by exposure to certain chemicals or radiation.

DNA:  Image Source: LaCasadeGoethe (artist). (2017



Real mutations don’t give anyone superpowers or turn them into monsters. The vast majority of mutations don’t cause any significant difference at all. If a mutation does have an effect, it’s far more likely to be damaging than helpful. Only a very small proportion of mutations do something useful for the organism.


These rare, beneficial mutations are the raw material that natural selection works on. If the new mutation is strongly selected for, it can spread through a population of organisms very quickly and become fixed in the population (meaning all organisms in the species or population have the trait).   


It’s very important to remember that the occurrence of natural mutations is completely random. The mutation for longer necks did not pop up in ancestral giraffes because they needed to have longer necks; the mutation appeared at random and quickly spread through the population and became fixed because it was so strongly selected for (that is, it gave giraffes with the mutation such a strong reproductive advantage).


Over the course of evolutionary time, mutations can give rise to new species and new traits in existing species. Mutations have given rise to all the diversity of organisms on Planet Earth. 


Image Citation:


LaCasadeGoethe (artist). (2017). DNA Project Lumina Walter [digital art]. Retrieved from

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