Back in the 1980s, researchers began to notice a strange pattern in the genes of many microbes. There would be a stretch of DNA that read the same forward and backward, then a stretch of what looked like junk, then another palindrome, and so on. No one knew what the segments were for, but they were striking enough that a pair of scientists in Europe dubbed them “clustered regularly interspaced short palindromic repeats,” or Crispr for short.

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