1964: Neanderthals are a sub-species
of humans
1997: Neanderthals are a separate species
(based on mtDNA find)
The results of mitochondrial DNA show clearly that Neandertal was not our direct ancestor, unlike earlier hypotheses made by some paleoanthropologists.
Luigi Cavalli-Sforza (Professor of genetics Stanford University), Genes,
People, and Languages, 2000, p. 35.