Parity Code And DNA

jnana writes "There's an interesting article in Nature about error-correcting parity code in DNA. It seems that there are enzymes that check for even-parity nucleotides (according to a 0 and 1 assignment scheme in the article) and recognize odd-parity nucleotides as errors. The authors argue that this parity scheme is the reason that adenine, thymine, cytosine, and guanine became the building blocks of nucleotides instead of other types of purines and pyrimidines that must have coexisted with them."