A team of Argentinean evolutionary analysts claim to have proved that Neanderthals and Homo sapiens were two completely different species.
Focusing on changes in skull types, the team looked at 3D casts of 17 hominid types as well as a gorilla, a chimpanzee and Homo sapiens. The base of the skull and its shape, jaw protrusion and the position of the face relative to the base of the cranium were all studied.
The results show that Homo sapiens’s most direct ancestor was Homo habilis whereas Neanderthal’s can at best be regarded as distant cousins as their skull types do not correspond with descent from this species.
No doubt this isn't the end of this particular debate.