1861, in reference to a type of extinct hominid, from German Neanderthal "Neander Valley," name of a gorge near Düsseldorf where humanoid fossils were identified in 1856. The place name is from the Graecized form of Joachim Neumann (literally "new man," Greek *neo-ander), 1650-1680, German pastor, poet and hymn-writer, who made this a favorite spot in the 1670s. Adopting a classical form of one's surname was a common practice among educated Germans in this era. As a noun, by 1915; as a type f a big, brutish, stupid person from 1926.
Note: The term Neanderthal is sometimes used to refer to a person who is thought to have primitive or unenlightened ideas: “I tried talking politics to Joe, but he's a real Neanderthal.”