You might fight about what name it's given, but someone's ancestry is definitely measurable and quite usable by whatever normal scientific tests you would normally come up with.
Just off the top of my head, there are over 93000 references in PubMed to "ancestry." They vary whether they call it "race" or "ethnicity" or "region of ancestral origin" but plenty of adults are quite happy talking about it.
You're strawmaning. I didn't say ancestry had no meaning. I said it wasn't determined genetically, which is 100% true. There's no blood test for "black", and I encourage you to cite one if you're aware of it. If you have a big population, you can do things like look at frequencies of specific gene variants and come up with a guess at where that population came from. But for one person there's just no way to do it. So: can a person, in isolation, be part of a genetic "race"? No.
There's no blood test for "black", and I encourage you to cite one if you're aware of it.
Now who is strawmanning? (BTW, there is no blood test for autism, yet scientists are pretty darn sure it's mostly genetic.)
I'm sure you can come up with a definition of "Polynesian" such that genetic tests would be useless. That more shows that people can some up with useless definitions. However, someone else can could up with a definition of "Polynesian" that is useful: people whose ancestors inhabited Polynesia (say) 1000 years ago. And genetic tests for any individual in isolation would be very very very highly correlated with the actual answer of their ancestors coming from Polynesia. (There are, of course, people of mixed ancestry, but this doesn't mean that ancestral measures don't exist no more than hermaphrodites mean sex doesn't exist.) "Black" would need serious subdivision, but nothing that makes a person on the street drop their jaw and say "I never thought of 'Black' that way."
I suspect this is as far as constructive discussion has gone, so I'm going to stop here if that's okay.
Arrgh. I still think you're fundamentally missing my point. You can't treat "black" via subdivision. The problem is mixing (i.e. most "blacks" are "half white", etc...), not imprecision. Basically you can't treat "black" at all. The term will never be useful to scientific study. The fact that there exist some identifiable ancestral groups will never (!) tell you anything useful about a typical "black" woman in america.
The same is true of "polynesian" -- sure, they might have been isolated at one point but by now almost every "polynesian" you meet in Hawaii has a ton of white and japanese ancestry too (substitute appropriate mixing for Maori or Samoan and Fijian, etc...), so what use is it to talk about the potential IQ effects his great-great-grandparents might have had?
Yet the argument at hand (that, as far as I can tell, you are in support of) is that somehow the "race" of real people can, because it is "genetically determined", be correlated with something like IQ, which it just can't. It's far too polluted a data set.
You're falling into the fallacy of the excluded middle. Just because "black" doesn't tell you everything about a person doesn't mean it can't tell you something useful.
That typical (now there's an overgeneral term!) black woman will have a darker skin color than a typical white woman. She will be less susceptible to sunburn. She is more likely to suffer from certain genetic diseases like sickle cell anemia.
Now, none of these are absolute statements. They are all probabilities. That does not make them useless. If someone comes into the ER with severe pain in their extremities, it is very useful to know that they're black. They may or may not have sickle cell anemia - that can be determined conclusively through a blood test and thorough medical examination. But knowing whether they're likely to is very useful information, because it lets you determine whether it's worth putting in the extra effort to diagnose it conclusively. (Similarly, even if they carry the genetic marker, they might not be having a sickle-cell crisis, and it could be a blood clot or some other medical condition. But it's pretty damn likely.)
It's a fallacy to believe that just because the data you're working with can't tell you everything, it tells you nothing. Rather, you should recognize the limitations of what you know, and use them to determine what else you need to know. Race tells you something. It doesn't tell you a whole lot, because there's a lot of individual variation within a race. But that doesn't mean it tells you nothing, either.
It doesn't even pass the smell test. Seriously: would Obama (who's turning into quite the counterexample here) show up "black" or "white" on that test? If the answer isn't "both" (it has to be, as he's almost literally 50/50) then the test can't work. If it is "both", then what meaning did "black" have again as a genetic grouping?
People insist on misinterpreting me here. I'm not saying that it's impossible to tell if someone has ancestry from africa or east asia or wherever. I'm saying that blocking real people (i.e. not members of an isolated subgroup with pure ancestry) up into a "race" like "asian" or (especially) "black", doing studies on them (like an IQ test) and arguing that this is "valid" because those groups are "genetically defined" is wrong. It's bad science. Please stop.
Thanks for the links. Here's my thoughts, take them or leave them: First, it's a big leap to go from the Harvard article's "here are theoretical issues with this test, not knowing any specifics of how it works" to "this doesn't work." There appear to be two components to the test, a genetic admixture, and predicted phenotypic characteristics that manifest with specific allele groupings, within a certain threshold of accuracy. Genes are not all equally heritable, there are dominant characteristics, so it can't be said that if someone is 50% one ethnicity and 50% another that you can't make any predictions about their appearance. This doesn't represent a rigid genetic definition of "race" I agree, but if it works for its intended purpose (matching phenotypic characteristics we generally associate with race to a genetic makeup) it opens the door to doing a blood test, finding someone's peak intelligence (assuming intelligence is heritable and measurable) according to some metric, and, possibly, associating that with a heritage/ethnicity/declared race, again within a certain accuracy threshold. (On the other hand, it may not extend all the way to heritable intelligence, or, the blood test might not even work for its intended purpose.) I also agree this would never mean that someone could say to an individual "you are a member of this race, therefore your intelligence peaks at IQ X" but you could use it to make predictions about an ethnic group in the aggregate.
I tried to qualify my statements here very carefully. I'm not claiming a strict genetic definition of race. I'm also not defending this specific blood test, I only know about it from that Wired article. But the theoretical possibility of what I have mentioned seems to exist, if that test or one like it actually works. Or am I mistaken?
Just off the top of my head, there are over 93000 references in PubMed to "ancestry." They vary whether they call it "race" or "ethnicity" or "region of ancestral origin" but plenty of adults are quite happy talking about it.