Neanderthals are the closest evolutionary relatives of modern humans. Based on fossil and archeological records, they are large-brained people with a distinct body plan and skull morphology compared to modern humans, associated with Mousterian (Middle Paleolithic) stone tools. Neanderthals had dominated in Europe and western and central Asia for 200,000 years, until their population declined for unknown reasons. After retreating to isolated refuges in southern Europe, they finally died out approximately 28,000 years ago.