Bennett Galef and Elaine Whiskin at McMaster University in Hamilton, Ontaria, Canada, put rats off cinnamon-flavoured food pellets by injecting the animals with a nausea-inducing chemical after their meals. Given a choice, these trained animals preferred to eat cocoa-flavoured food pellets.
However, when those rats then spent time with "demonstrator" rats that had just eaten and smelt of cinnamon, they regained their liking for it (Animal Behaviour, DOI: 10.1016/j.anbehav.2007.11.012).
Until now, humans and chimps were the only other animals known to conform in this way. Andrew Whiten from the University of St Andrews, UK, says that the discovery emphasises the importance of social learning in the animal kingdom.
The big question now, he says, is why they conform. "It's not immediately obvious why a rat or chimp or human would cast aside what it knows from its own experience and adopt an inferior course of action just because everybody else is doing it."