On the other hand, we really did invent the eugenic concept, as implemented for example by the Nazi regime, and even that example wasn't enough to stop some states, such as California, forcibly sterilizing their own citizens for explicitly eugenic purposes until at least a couple of decades after.

You're not quite wrong about American exceptionalism in its negative application here. (You're far from wholly right, though - people question the Constitution, for example, all the time.) But the Progressive Era in the US really does have a hell of a lot to answer for. That's whence came the modern concept of engineering a society en bloc, and treating its members however harshly seemed necessary to fit them into the overarching structure of some notional greater good. That's what Huxley was satirizing in Brave New World. Where did you think he got the idea?

Sir Francis Galton (a Brit) invented the term "eugenics." The Wikipedia article on Eugenics notes that the concept of selective breeding of humans dates back to at least Plato.

Additionally the Wikipedia entry indicates that the modern Eugenics movement started in the UK before spreading to the US, Canada and most other European countries.

https://en.wikipedia.org/wiki/Eugenics

> That's whence came the modern concept of engineering a society en bloc, and treating its members however harshly seemed necessary to fit them into the overarching structure of some notional greater good.

really? you should read some Egyptology.

I have. That's why I said "modern".

I've never heard anyone say that you can't change the Constitution, only that if you want to do something that is current unconstitutional, you have to change it first. See gun control, the belief in the hard-line pro-2A community is that if you want to restrict the right to purchase, own, and use firearms, you have to introduce another amendment either changing or clarifying (based on your viewpoint) the second amendment. Please don't start a[n anti-]gun control argument here, that's not the point.

I was thinking of phenomena like Originalism: https://en.m.wikipedia.org/wiki/Originalism

If the Constitution were a living document, the Originalist viewpoint would not make any sense.

In many other countries, constitutional laws get semi-regularly rewritten and modernized, not just amended.