Despite his exhaustive archival research, Bert Theunissen confesses he is none the wiser about when and why Dubois decided to take the radical step of going halfway around the world in search of the link between the anthropoid apes and modern humans.
Given the influence of Ernst Haeckel on Dubois' teachers, and the popularity of Haeckel's books, it is inconceivable that Dubois was not influenced by Haeckel's conviction that modern humans are more closely related to the extant apes from South-East Asia (Nusantara in Malay) than they are to the African apes, which was Darwin's position. So, just as Darwin had identified Africa as the place to look for fossil evidence of human ancestors, Haeckel had pushed the case for Nusantara. Dubois failed to persuade the Dutch Colonial Office to support an expedition to the Dutch East Indies to look for fossils, so he joined the Royal Dutch East Indies Army as a Medical Officer Second Class, and on the 28th October, 1887, together with his new wife Anna, he set sail from the Netherlands en route to Sumatra. Despite his exhaustive archival research, Bert Theunissen confesses he is none the wiser about when and why Dubois decided to take the radical step of going halfway around the world in search of the link between the anthropoid apes and modern humans.