Before Pepperberg's work with Alex, it was widely believed in the scientific community that a large primate brain was needed to handle complex problems related to language and understanding; birds were not considered to be intelligent as their only common use of communication was of mimicking and the repetition of sounds to interact with each other. However, Alex's accomplishments supported the idea that birds may be able to reason on a basic level and use words creatively.[5] Pepperberg wrote that Alex's intelligence was on a par with that of dolphins and great apes.[6] She also reported that Alex seemed to show the intelligence of a five-year-old human, in some respects,[3] and had not even reached his full potential by the time he died.[7] She said that the bird had the emotional level of a human two-year-old at the time of his death.[8]