On page 282 of "Stamped from the Beginning," Kendi discusses a Du Bois speech wherein Du Bois "put forth the argument of biologically distinct races with distinct histories, characteristics, and destinies."
He further argued that African Americans were members of a historic race and that they remained "but half awakening in the dark forests of the African fatherland." Du Bois thought "[t]he first and greatest step toward the settlement of the present friction between the races . . . lies in the erection of the immorality, crime, and laziness among" African Americans. These ideas seem to fall in the assimilationist school of thinking that Kendi identifies because Du Bois is arguing that the solution to racism is for black people to change their "black behaviors," like "Crime, immorality, and laziness" to be more like white behaviors. Obviously this thinking relied on racist assumptions that "black behaviors" include laziness, immorality, and crime and that whites behave fundamentally differently. What is interesting, as Kendi points out, is that these ideas were spread in an alleged effort to "refute the popular conception of the destructive, decaying, dying African." Apparently, the goal here was to spread into popular conception the idea that African Americans were superior to continental Africans. This speech was in 1897.
This idea of biologically distinct races, regardless of what Du Bois was attempting when he spread it, must have caught traction. When I read these pages, I was reminded of the opinion in Kinney v. the Commonwealth, the predecessor case to Loving v. Virginia, where Judge Joseph Christian justified the ban on interracial marriage with the idea that black people and white people were different species and were put on different continents by God so that they would not reproduce: “The purity of public morals, the moral and physical development of both races, and the highest advancement of our cherished southern civilization, under which two distinct races are to work out and accomplish the destiny to which the Almighty has assigned them on this continent require that they should be kept distinct and separate, and that connections and alliances so unnatural that God and nature seem to forbid them, should be prohibited by positive law, and be subject to no evasion.” This case was in 1878, a few years before Du Bois "put forth the argument of biologically distinct races." This example seems consistent with Kendi's idea that racist policies generate racist ideas in order to justify the racist policies.