Though Huxley was a great comparative anatomist and invertebrate zoologist, perhaps his most notable scientific achievement was his work on human evolution. Starting in 1858, Huxley gave lectures and published papers which analysed the zoological position of man. The best were collected in a landmark work: "Evidence as to Man's Place in Nature" (1863). This contained two themes: first, humans are related to the great apes, and second, the species has evolved in a similar manner to all other forms of life. These were ideas which the careful and cautious Darwin had only hinted at in "The Origin of Species", but with which Huxley was in full agreement.