Since their first discovery, Neandertals have served as an out-group for interpreting human variation. Their out-group role has changed over the years because in spite of the fact that Neandertals are the most abundant of all fossil remains (or perhaps because of this) their interpretation is the most controversial of all human fossils. Many believe them to be a different, albeit human-like species, but recent genetic evidence supports anatomical interpretations indicating that interbreeding with other humans was an important aspect of human evolution. The combination of anatomical difference and restricted gene flow between populations suggests the possibility that Neandertals may have been a true human race. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc.