Bedrockgames
I post in the voice of Christopher Walken
Also I am just going by the wikipedia page here, so take with the appropriate grain of salt, but this the section on classification of neanderthals and common ancestors with humans and denisovans. Just so people have a point of reference:
Neanderthals are hominids in the genus Homo, humans, and generally classified as a distinct species, H. neanderthalensis, although sometimes as a subspecies of modern human as H. sapiens neanderthalensis. This would necessitate the classification of modern humans as H. sapiens sapiens.[8]
A large part of the controversy stems from the vagueness of the term "species", as it is generally used to distinguish two genetically isolated populations, but admixture between modern humans and Neanderthals is known to have occurred.[8][129] However, the absence of Neanderthal-derived patrilineal Y-chromosome and matrilineal mitochondrial DNA (mtDNA) in modern humans, along with the underrepresentation of Neanderthal X chromosome DNA, could imply reduced fertility or frequent sterility of some hybrid crosses,[86][130][131][132] representing a partial biological reproductive barrier between the groups, and therefore species distinction.[86] In 2014 geneticist Svante Pääbo summarised the controversy, describing such "taxonomic wars" as unresolvable, "since there is no definition of species perfectly describing the case".[8]
Neanderthals are thought to have been more closely related to Denisovans than to modern humans. Likewise, Neanderthals and Denisovans share a more recent last common ancestor (LCA) than to modern humans, based on nuclear DNA (nDNA). However, Neanderthals and modern humans share a more recent mitochondrial LCA (observable by studying mtDNA). This likely resulted from an interbreeding event subsequent to the Neanderthal/Denisovan split which introduced another mtDNA line. This involved either introgression coming from an unknown archaic human into Denisovans,[89][90][128][133][134] or introgression from an earlier unidentified modern human wave from Africa into Neanderthals.[135]