We never let science interfere with our prejudices; see for example the Supreme Court's reasoning in [1], in which they rejected a scientific definition of race for the purposes of interpreting a statute. However, we always did and still do assume that our beliefs about race (whatever they are) are grounded in biological reality and will be vindicated by science. In the Supreme Court case I linked, after the justices set aside science in favor of "the understanding of the common man," they still felt compelled to discuss scientific theories and imply that a sufficient examination of the scientific evidence would support the same ruling.

[1] http://www.digitalhistory.uh.edu/asian_voices/voices_display...

These categories are hardly arbitrary, they are political. We separate people into republicans and democrats, too, but just because this separation is not based on genetics or geography does not make it arbitrary or even bad.

Don't confuse genetic/geographic science with science as a whole. Anywhere you can do experiments you can do science, and politics is no exception (although everything is much noisier). Certainly, the groups of people described by the census are meaningful in a scientifically confirm-able way: they identify with each other, forming clearly discernible self-selecting cliques, neighborhoods, etc.

If he wants to say "the races as defined by the census are only weakly correlated with genetic distance or geographic ancestry", then fine. But that's a far cry from "the 'race' categories that are used in the United States are arbitrary...and do not correspond to any scientific view of geographical populations."

> The hominin line of descent that branched into H. sapiens had to develop skin that began dark and persisted as dark as humans lost body hair and began living in savannah environments with less shade than forests, according to the currently accepted hypothesis. As population bottlenecks in Africa formed the species H. sapiens, presumptively the typical skin color of all modern humans was dark (within a pattern of continued variation among individuals and a continued capacity for individual skin color to vary over the course of seasons).

These two comments, separated in your text by references, seem opposites (ancestral condition was pale...began dark), and the linked texts do not support both of these opposites. But I think you meant humans began pale, became universally dark, then some became pale again.

In any case, all the references you provide support the original post's hypothesis: skin color was affected by both diet and interaction with the sun, each round of research adding a new mechanism to the previously suspected mechanisms (not refuting the previous).

The original post here adds to the collective info you supplied, and neatly explains an otherwise startling variance between their hypothetical charts and the actual charts, that would seem at first blush to invalidate the prior theories but in fact confirms them.

You wrote a lot in your reply, and HN appreciates and votes up for effort. With the mix of personal anecdote (lived everywhere, I'm nordic and my wife's Asian), the gist is that you're adding insight.

However, with your two major paragraphs proposing at least one view that's opposite to your linked research (skin that began dark vs chimps pale skin), and with none of your comments or links addressing or negating the original article's added insight about grain and the loss of vitamin D, I can't tell what you're intending to convey.

It seems your exec summary might have been, "Without addressing the original article which I call 'just a hypothesis', I'd like to say I've seen skin shade variations everywhere including seasonality in my own kids; I am linking research that the linked article builds on; and populations' genes are getting more mixed though even people with pale skin have it for different genetic reasons."

Ok. But not one word of that refutes (or ever directly comments on) the thesis of the original article linked here.

To summarize your reply while tying in the original article, we could say (in a sort of TL;DR):

"The original article explains historically sharply defined regional skin color bands in terms of UV exposure and diet, adding grains and the gulf stream to prior theories involving UV and fish and meat. This explains regions that were problematic for earlier theories. But in today's highly mobile world, people like my own family are becoming more mixed than ever and these regional bands are becoming less sharply distinct. We should be cautious of the increasingly arbitrary politics of race."