[snip]The English used to feel pretty uncomfortable about yanks grinning away at everything[/snip]
That surprised me, since our cultural norms largely stemmed from there.So what would account for the difference? It must've come about after we split as a country.
I wonder if it's our Declaration of Independence including "the pursuit of Happiness". See:
We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness.
Nowhere else in the world (up until then, anyway) gave as its founding commandment that being happy was an indicator of a life well-lived.Thus, perhaps, while other places reserve the effort of smiling for the emotion of irrepressible joy, Americans -- to prove they're living a good life -- present a smile.
I don't think that assumption really holds up, it's very pop-history. From the Scots of the Appalachians, the religious fanatics of New England, the garguntuan influence of African-American syncretic culture, the Nordic yeoman of the mid-north-east, the southern European urban influx of the 1900s and the new, exciting Latin American syncretism: America really is a cultural melting pot. Only, really, the Virginia gentry (Jefferson, Washington, et al) can be plainly said to have imported English norms - and still, they were ideological radicals interested in forming a new nation.
The French like to call us (English, Scots, and all the varieties of American) "Anglo-Saxons," but they're hardly right. Don't give them ammo, they're already merciless!
People often assume something's wrong if you never smile, or, worse, frown.
People sometimes have good time (better than avg), sometimes bad time, and sometime neutral time (say.. thinking about some problem to solve, or repeating Swedish vocabulary to learn a new language, or trying to recall the name of a person you just met and you're supposed to remember).
If you're compelled to smile with every interaction, in order to show that you have good time, then it'd mean that you'd be mostly lying according to the aforementioned definition :).
Unless we re-define the 'good time', so it means 'not significantly bad', which seems to be the case here. It's just, that it requires a bit of effort to remember and to switch to when visiting US.
Another historical explanation, as has been mentioned by other commenters, is that it was due to the popularization of African American culture.
But of course, they are just two of the many plausible historical explanations.