The last 10 years have transformed the evidence concerning the early origins and evolution of Neanderthal populations. Genetic comparisons of Neanderthal and Denisovan ancient DNA suggest that the common ancestor of these populations separated from African ancestors of modern humans prior to 600,000 years ago, followed by a rapid differentiation in Eurasia. Later, additional episodes of gene flow brought genes into Neanderthal populations, including the mtDNA clade carried by all later Neanderthals. Yet, a number of western Eurasian fossil samples from the time between 600,000 and 100,000 years ago are difficult to accommodate within the category of "Neanderthals", including European...