Does your friend believe that other species besides humans have different subspecies or races? like dogs, wolves, horses, bears, goats, etc...    If so, first agree that those species do have different races and it's important to keep them separated in their own space to preserve the biodiversity, agree that otherwise we would end up with one race of mud dogs, horses, bears, etc... then point out that the genetic variance in many of those species that do have racial divisions are indeed lower than the genetic variation between human races, therefore we can conclude that the concept of race in humans is valid by the same standards as with other species and biologically and genetically real, and then you can aboard the topics of racial segregation and white-homelands. ;)     Read this:   http://wiki.majorityrights.com/race    :clink