Your remarks in the last two paragraphs are right on. What we should be concerned with is the moral and political meaning and consequences of a certain classification. If "species" came to be thought of in such a way that a bunch of us on this board turned out to belong to different species, would that change anything about how we should be treating each other? No.
Someone sympathetic to the moral relevance of racial distinctions could reason as follows: What species we belong to is morally relevant. We are allowed to prize and protect our species and we have more responsibility towards members of our species than we do towards other things. If races indeed belonged to different species, then it would not be inappropriate for us to act differentially toward people according to their race. So now that we have discovered that whites and blacks belong to different species, as a white, I can justify my discriminatory behavior towards blacks.
I don't find the key premise of this reasoning in the least acceptable, so I am reluctant to ascribe it to anyone. But one wonders whether something of this sort is lurking behind a bunch of the remarks above.
It's really late right now and I have to resist the urge to elaborate. I will add some comments later.
Someone sympathetic to the moral relevance of racial distinctions could reason as follows: What species we belong to is morally relevant. We are allowed to prize and protect our species and we have more responsibility towards members of our species than we do towards other things. If races indeed belonged to different species, then it would not be inappropriate for us to act differentially toward people according to their race. So now that we have discovered that whites and blacks belong to different species, as a white, I can justify my discriminatory behavior towards blacks.
I don't find the key premise of this reasoning in the least acceptable, so I am reluctant to ascribe it to anyone. But one wonders whether something of this sort is lurking behind a bunch of the remarks above.
It's really late right now and I have to resist the urge to elaborate. I will add some comments later.