According to Gregg, a researcher with the Dolphin Communication Project in America and co-editor of journal Aquatic Mammals, although dolphins show signs of complex behaviour- such as living in large social groups, empathy and communicating with peers- chickens, pigs and bears also show these traits.
The researcher also claimed that other scientists had made mistakes, most crucially that dolphins' large brains equal greater intelligence and that the complex sounds they make are a form of language.
Source: ANI