In the June issue of The American Journal of Human Genetics, Scholz et al. have demonstrated significant genomic differences between DNA samples from Neandertal and modern human fossils. Using a simple method to assess the cross-hybridization of fossil DNA, the authors were able to distinguish two well-defined Neandertal fossils from that of a modern human. For a significant amount of hybridization variation to occur, substantial differences between the genomes of these fossils must be present, and these differences are most likely found within repetitive sequences. These results argue that Neandertals and modern humans arose from separate lineages, thereby refuting the classification of Neandertals as a subspecies of Homo sapiens. Although this method measures total genomic variation, rather than specific genetic sequences, it may allow classification of fossils for which morphology studies could not provide definitive results, which in turn will provide further clues to the evolutionary history of humans.