Cognition and Aging

Rhesus macaques in the outdoor corrals at the California Regional Primate Research Center

It's "enrichment" time in a long room at the California Regional Primate Research Center (CRPRC) on the University of California's Davis campus. When we peer through a little window in the door, most of the rhesus macaques in wall-mounted cages are looking away from us, toward the television. A nature show is airing. Jeffrey A. Roberts, assistant director, primate services, comments that whenever monkeys are shown on TV, all eyes are glued to the set. A few of the monkeys reach out and adjust plastic mirrors attached to the bars of their cages, the better to watch us watching them. We don disposable galoshes, gloves, and face shields, then venture into the room. The animals stare in silence, their mouths and eyes forming tripods of circles. Their skin is wrinkled and blotchy, the eyes rheumy; this...