Animals differ strikingly in character and temperament. Yet only recently has it become evident that personalities are a widespread phenomenon in the animal kingdom. Animals as diverse as spiders, mice and squids appear to have personalities. Personality differences have been described in more than 60 species, including primates, rodents, birds, fish, insects and mollusks.
New work by Max Wolf (University of Groningen; currently at the Santa Fe Institute), Santa Fe Institute Postdoctoral Fellow Sander van Doorn, Franz Weissing (University of Groningen), and Olof Leimar (Stockholm University…