Nearly 25 years after scientists completed a draft human genome sequence, many of its 3.1 billion letters remain a puzzle. The 98% of the genome that is not made of protein-coding genes — but which ...

The ability to extract trace bits of DNA from soil, water, and even air is revolutionizing science. But it's not foolproof. In the late 1980s, at a federal research facility in Pensacola, Florida, ...