So, he concluded that the animals were capable of problem-solving and that they did "not" arrive at their methods through trial and error. This is one of the most important findings from the research done on apes. Köhler’s work on the mentality of apes was a turning point in the psychology of thinking. In the 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” Köhler (1925). The fact that human traits can be observed in the everyday behaviours of this animal was very intriguing for Köhler. Kohler also wanted to gain knowledge of the nature of intelligent acts.