What, genetically, is a race?
That’s something that can be tested for with relative ease.
> Ancestry informative marker sets for determining continental origin and admixture proportions in common populations in America
> ... A comprehensive set of 128 AIMs and subsets as small as 24 AIMs are shown to be useful tools for ascertaining the origin of subjects from particular continents, and to correct for population stratification in admixed population sample sets.
As population genetics becomes more advanced we will become able to distinguish ever smaller ancestry ancestry groups. For example if you don’t try to identify Continental population ancestry, just use k means clustering to divide humans into clusters based on similarity the continental groups arise naturally.
> Genetic Structure of Human Populations
> Genetic Structure of Human Populations Noah A. Rosenberg,1* Jonathan K. Pritchard,2 James L. Weber,3 Howard M. Cann,4 Kenneth K. Kidd,5 Lev A. Zhivotovsky,6 Marcus W. Feldman7 We studied human population structure using genotypes at 377 autosomal microsatellite loci in 1056 individuals from 52 populations. Within-population differences among individuals account for 93 to 95% of genetic variation; differences among major groups constitute only 3 to 5%. Nevertheless, without using prior information about the origins of individuals, we identified six main genetic clusters, five of which correspond to major geographic regions, and subclusters that often correspond to individual populations. General agreement of genetic and predefined populations suggests that self-reported ancestry can facilitate assessments of epidemiological risks but does not obviate the need to use genetic information in genetic association studies.
http://www-leland.stanford.edu/~huatang/gene244/readings/Sci...
Get someone to show you pictures and have you identify them. I bet you'll make a lot of mistakes.
Historically, not only can people not tell the difference objectively, they decide what the difference is subjectively. In the United States, the child of a white slave owner and a black slave, if their parentage was known, was ... black. People of "mixed race" might be deemed a different race than their own full siblings, based on which visible characteristics they got from which ancestor.
Even today, people migrating from one country to another are often surprised that their racial classification is different in the new country than at home.
> Get someone to show you pictures and have you identify them. I bet you'll make a lot of mistakes.
I’m going to sleep now but if you find ten pictures of each I’ll be happy to do your survey. I’m sure many others would be too if you put it on surveymonkey.
The overlap in skin tone alone between Caucasians and the other two groups is ~0 so I doubt there would be any mistakes there. I’m sure there would be many more mistakes between Melanesians and Sub Saharan Africans but even just going on whether they have a broad nose or not you’d get pretty far distinguishing SSA from Melanesians. I’m not claiming perfect distinction. I’m claiming that doing better than chance is unremarkable. These groups are visibly different on average. Some groups the population values don’t even overlap. The shortest adult Maasai is taller than the tallest adult Pygmy.
> In the United States, the child of a white slave owner and a black slave was... black.
Who cares about the historical American caste system, with its one drop rule? The social construction of race is a real thing and so is the fact that different ancestry groups are different, and can be distinguished, on average and subject to error. Pretending ancestry is entirely socially constructed is crazy. If you get thirty pictures, 10 East Asian, 10 West Eurasian, and ten people who are first generation crosses from both populations, there is very unlikely to be any mislabelling of the base population individuals.
If you go back far enough all humans come from Africa, and most (at least 90%) comes from the latest Out of Africa expansion, ~200K years ago. But all non SSA humans are 2% Neanderthal, on average, and there’s other archaic hominid introversion that varies by geography. The Tibetan high altitude adaptations are probably 2 million years old.
Which ancestors one refers to will depend on the question you’re asking.
There was a movement in the 90s to get rid of the word "race" because scientists said all humans are basically the same. However, that movement has dwindled because we are discovering some important differences between ethnic groups. Such as:
* Blacks are more sensitive to salt
* Blacks are at a greater risk of glaucoma
* etc
https://www.scientificamerican.com/article/race-is-a-social-...
> Yudell said that modern genetics research is operating in a paradox, which is that race is understood to be a useful tool to elucidate human genetic diversity, but on the other hand, race is also understood to be a poorly defined marker of that diversity and an imprecise proxy for the relationship between ancestry and genetics.
> ...
> "What the study of complete genomes from different parts of the world has shown is that even between Africa and Europe, for example, there is not a single absolute genetic difference, meaning no single variant where all Africans have one variant and all Europeans another one, even when recent migration is disregarded," Pääbo told Live Science. "It is all a question of differences in how frequent different variants are on different continents and in different regions."
> In one example that demonstrated genetic differences were not fixed along racial lines, the full genomes of James Watson and Craig Venter, two famous American scientists of European ancestry, were compared to that of a Korean scientist, Seong-Jin Kim. It turned out that Watson (who, ironically, became ostracized in the scientific community after making racist remarks) and Venter shared fewer variations in their genetic sequences than they each shared with Kim.
> ...
> "If you make clinical predictions based on somebody's race, you're going to be wrong a good chunk of the time," Yudell told Live Science. In the paper, he and his colleagues used the example of cystic fibrosis, which is underdiagnosed in people of African ancestry because it is thought of as a "white" disease.
That said, skin colour does have some physiological impact: darker skin blocks the impact of the sun on our skin, which is great for preventing sunburn (and skin cancer, I think?), but reduces the amount of vitamin D our skin creates, and vitamin D deficiency can have an impact on all sorts of things (no idea if glaucoma is one of them). That makes it a trait, though, not a race.