It was late summer, and the gray towers of the Salk Institute, in San Diego, shaded seamlessly into ocean fog. The austere, marble-paved central courtyard was silent and deserted. The south lawn, a peaceful retreat often used for Tai Chi and yoga classes, was likewise devoid of life, but through vents built into its concrete border one could detect a slight ammoniac whiff from more than two thousand cages of laboratory rodents below. In a teak-lined office overlooking the ocean, the biologist Ron Evans introduced me to two specimens: Couch Potato Mouse and Lance Armstrong Mouse.
