Herein, I review the Finnish palaeontologist Björn Kurtén's (1924–1988) views on human evolution, as he presented them in his books. In particular, I discuss Kurtén's controversial hypothesis of an ancient, Oligocene separation of the human and great ape evolutionary lineages. This hypothesis, which he argued for strongly in the early 1970s, was based mainly on the idea that the human dentition could not have evolved from an ape-like dentition. Kurtén thought that some of the fossil primates known at the time, especially Propliopithecus and Ramapithecus from the Oligocene and the Miocene, respectively, were plausible human ancestors because of their supposedly human-like dentitions. New lines of scientific evidence forced Kurtén to abandon his ‘not from the apes’ hypothesis in the 1980s. However, he continued to speak favourably of other minority views within palaeoanthropology, such as the so-called aquatic ape hypothesis, until the end of his life.