In a way, sequencing DNA is very simple: There's a molecule, you look at it, and you write down what you find. You'd think it would be easy—and, for any one letter in the sequence, it is. The problem ...

Students take samples of water and the microscopic creatures within at the Alviso Marina County Park. (Image by Erika Cardema) At the Alviso Marina County Park, reddish-brown water laps at the edge of ...