Of all the possible amino acids, all living organisms make use of only the same 20 amino acids. This supports the idea that:

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The fact that all living organisms make use of only the same 20 amino acids suggests that they all evolved from a single common ancestor. This is because the genetic code for these amino acids is universal across all life forms, indicating that they were present in the original genetic code of the first living organism. This idea is supported by other lines of evidence, such as the similarities in DNA and protein sequences among different species.

Of All the Possible Amino Acids, All Living Organisms Make