Effects of isolation and grouping on guinea pigs

Guinea pigs spent 80 days in isolation or same-sex groups beginning either immediately after weaning or in adulthood. Isolated animals were more active in a cross maze, but not in an open field. No group of animals preferred a goal guinea pig in a four-choice test. Males isolated at weaning meeting another such male were more aggressive than males in isolated-grouped or grouped-grouped encounters, but did not make more nonaggressive contacts. Males isolated in adulthood meeting other such males exhibited more nonaggressive behavior, but not more fighting. Use of “gregariousness” as a unitary concept is questioned.