In his 1775 doctoral dissertation titled "De Generis Humani Varietate Nativa" (trans: "On the Natural Varieties of Mankind"), Blumenbach outlined Johann Friedrich Blumenbach main human races by skin color, geography, and skull measurements; namely "Caucasians" (white), "Ethiopians" (black), "Americans" (red), and the "Mongolians" (yellow). Blumenbach added Austronesians as the fifth category to his "varieties" of humans in the second edition of "De Generis" (1781). He initially grouped them by geography and thus called Austronesians the "people from the southern world." In the third edition published in 1795, he named Austronesians the "Malay race" or the "brown race," after studies done by Joseph Banks who was part of the first voyage of James Cook. Blumenbach used the term "Malay" due to his belief that most Austronesians spoke the "Malay idiom" (i.e. the Austronesian languages), though he inadvertently caused the later confusion of his racial category with the Melayu people. The other varieties Blumenbach identified were the "Caucasians" (white), "Mongolians" (yellow), "Ethiopians" (black), and "Americans" (red). Blumenbach's definition of the Malay race is largely identical to the modern distribution of the Austronesian peoples, including not only Islander Southeast Asians, but also the people of Madagascar and the Pacific Islands. Although Blumenbach's work was later used in scientific racism, Blumenbach was a monogenist and did not believe the human "varieties" were inherently inferior to each other. However he believed in the "degenerative hypothesis", and believed that the Malay race were a transitory form between Caucasians and Ethiopians.