This is one of the prominent findings from the research done on apes. Köhler's work on the mentality of apes was seen as a turning point in the psychology of thinking. He believed that people underestimated the influence of a number of external conditions on such higher animals. In his book, "The Mentality of Apes", Köhler explains that he was inspired to work with the chimpanzees for two main reasons. The first was because the "structure of their brains is more closely related to the chemistry of the human body and brain-structure than to the chemical nature of the lower apes and their brain development". He was intrigued that human traits could be observed in the everyday behaviours of this animal. Secondly, he wanted to study the chimps to gain knowledge of the nature of intelligent acts.