Yeah, the basic definition of a "species" is one that has been mentioned by other people already. Since Africans can breed effectively with every other race, we are all the same species.
In the scientific community, there are some discussions about the origins of humanity, mostly centering around whether humans all come from the same tribe, or whether humans evolved simultaneously in different areas. But whatever the case, the genetic records show without a doubt that there is a surprising diversity within races, and a surprising conformity throughout humankind. Meaning, a fellow Gaelic person like myself can actually -on the genetic level- be very different from me. While someone of African descent can be surprisingly and comparatively similar.
This diversity of genetics is actually necessary and vital to the human race, because it allows for a wider-array of immune-defenses. With genetic conformity comes a narrowing of the human immune system's defenses, but genetic diversity widens these, allowing humans to survive more easily.
Of course, race itself plays only a minor role in determining how diverse a person's immune system is, but proof that Africans or any other race is genetically divergent only strengthens the case for interbreeding between the races in question.