Is Race Real? Brace and Gill at NOVA

Here's a nice little informal discussion of the question "is race real?"
On the negative side is C. Loring Brace, on the affirmative, George W. Gill.
I'm not going to go through the whole thing now, but here's Brace's first argument for his conclusion:

But if one were to walk up beside the Nile from Cairo, across the Tropic of Cancer to Khartoum in the Sudan and on to Nairobi, there would be no visible boundary between one people and another. The same thing would be true if one were to walk north from Cairo, through the Caucasus, and on up into Russia, eventually swinging west across the northern end of the Baltic Sea to Scandinavia. The people at any adjacent stops along the way look like one another more than they look like anyone else since, after all, they are related to one another.

And the conclusion in play is, roughly: racial distinctions are unreal.

But this is the continuum fallacy, of course.

From:

There is a spectrum/continuum of states between A and B

We cannot infer:

There is no real difference between A and B.

There could, for example, be a large number of actual (or an infinite number of possible) gradations of difference between species A and species B, but that doesn't mean that the two species are not distinct.

And take, say, this dude.

Now, pluck out one of his hairs. There will be no visible difference. Then pluck out another one. No visible difference again. But keep doing this, and eventually you will hit an end state in which there is an enormous difference as compared to the initial state. There will be no visible difference between any two adjacent states. But go through enough of these state changes, and the end states will be visibly different.

I know some people really, really want race to be unreal. Personally, I don't have a rooting interest. I do think it would make humanity less interesting if there were no races... But I suppose there is some possibility it would help solve some moral and political problems... It's bad to allow political aspirations to influence scientific conclusions... And, even if we did violate the rule, I doubt that we'd gain any moral yardage...racists don't care whether race is real or fictive or created by the magical power of social agreement or whatever. 

But the bottom line is: the continuum fallacy is a fallacy, and invalid arguments provide exactly no support for any view. If racial antirealists really do care about the truth of their case, they'll drop these continuum arguments. 

That would be very damaging, however, since it seems that a lot of people who believe the view believe it on the basis of such an argument.