• Question: would you believe in the theory of evolution if you find similar dna in different species of aninmals?

    Asked by to Heather on 19 Jun 2014. This question was also asked by .
    • Photo: Heather Ritchie

      Heather Ritchie answered on 19 Jun 2014:

      The vast majority of DNA is incredibly similar between species hence why 50% of our DNA is exactly the same as a banana’s! When we are looking at different species we look at what is called mitochondrial DNA (mtDNA). Mitochondrial DNA is a small circle of DNA that is found in our mitochondria within cells (where mitochondria are just one of many parts of a cell). This type of DNA is different to genomic DNA (the genome) and we call it neutral which means it isn’t being affected by the outside environment so any changes in it happen because of random mutations over time. The differences in this kind of DNA are used to estimate how different species are from each other.

      So if one species had the DNA (species 1) AGAGCTA
      And another had (species 2) AGAGCTT
      And a very different one had (species 3) ATCGATA

      Then we can say that species 1 and species 2 are more closely related because they have only 1 change in 7 letters but that species 1 and species 3 and futher apart because they have 3 changes in 7 letters.

      So every though DNA is often very similar there are very small and subtle changes that help us to find out how evolution has changed one species into another.

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