The orangutan was first described scientifically in 1758 in the "Systema Naturae" of Carl Linnaeus as "Homo Sylvestris". It was renamed "Simia pygmaeus" in 1760 by his student Christian Emmanuel Hopp and given the name "Pongo" by Lacépède in 1799. The populations on the two islands were suggested to be separate species when "P. abelii" was described by French naturalist René Lesson in 1827. In 2001, "P. abelii" was confirmed as a full species based on molecular evidence published in 1996, and three distinct populations on Borneo were elevated to subspecies ("P. p. pygmaeus", "P. p. morio" and "P. p. wurmbii"). The description in 2017 of a third species, "P. tapanuliensis", from Sumatra south of Lake Toba, came with a surprising twist: it is more closely related to the Bornean species, "P. pygmaeus" than to its fellow Sumatran species, "P. abelii".