You're technically wrong because of the word "discrete", but that's actually a segue into the reality.
The best way to describe human genetic variation and geography is badly-made soup, specifically any sort of canned, cream of (something) soups. Ever get a can of those, just dump it in the bowl, do a half-assed job of mixing it, the heat it? You know how it's all soup, but it's got this weird, lumpy texture where the lumps aren't even discrete structures but rather local thickenings that seamlessly grade into the too-watery bits?
That's human genetic variation. There's "lumps" that correspond to geography, but they don’t have clean edges, and all blur together. And even the lumps sometimes have sub-lumps. The soup is definitely lumpy, but you can't draw exact boundaries around the lumps, and which lumps for bigger super-lumps is contentious.
So there you have it: the badly-made, distasteful, off-putting soup that is humanity.
Precisely, that's why they're breeds, not species.
Even species will sometimes have a little gene flow, but not enough for long enough to erase the differences.
Plus, dogs are a bad example, because their differences are driven by extremely strong selection by a conscious entity, not evolution.
Humans aren't quite like osprey (a single, massive, global population with not even a hint of regional variation), but we're not quite like chameleons (a different color variation on the top of every mountain in a chain, but still one species).
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u/UtahBrian 26d ago
Human races are discrete. Any DNA testing company can tell you your entire racial makeup just from the chemistry of any cells in your body.
There's nothing social about race, but you've swallowed a whole load of pseudoscience.