One lecture (chapter) [of Genes, People, Languages by Luigi Luca Cavalli-Sforza] however , includes a most exacting meaning for the term "race".

You might want to check out what Cavalli-Sforza and son say about race in their The Great Human Diasporas: The History of Diversity and Evolution 1995: "The idea of race in the human species serves no purpose. The structure of human populations is extremely complex and changes from area to area; there are always nuances deriving from continual migration across and within the borders of every nation, which make clear distinctions impossible." The 9th chapter of the book (on Race and Racism) from which this excerpt comes sums up pretty much how I feel about the term race and its "meaning".