Physical exercise and mental stimulation change both the brains and sperm of male mice, allowing them to transmit the benefits of their experiences to their offspring.

André Fischer at the German Center for Neurodegenerative Diseases in Göttingen and his colleagues housed male mice in either standard cages or upgraded models that featured toys and running wheels. When the researchers repeatedly stimulated the animals’ hippocampal neurons, both groups of mice developed stronger neuronal connections — a process thought to be crucial to learning and memory. But the effect was enhanced in animals exposed to enriched environments — an advantage that persisted in their offspring.

Mice sired by males from enriched environments also did slightly better on simple cognitive tests than mice whose fathers had duller homes. The ‘advanced’ fathers transmitted their legacy, in part, by way of higher levels of two small RNA molecules — both linked to brain development and memory — in the fathers’ sperm.