The resultant smiles are differently interpreted by the different cultures.

Sparteye: I read a report on the same research, only in a different newspaper, the Toronto Star [link below]. I was so taken with the "Pan Am" smile [Tom Cruise's "Star Spangled Grin"] that I wrote a limerick about it. [I never thought I would have occasion to post it, however.]

You can tell a lot about a smile.
If it's Pan Am it'll stretch a mile.
Wide open means the States.
A Brit less openly relates
'Cause stiff upper lip is his style.

THE STAR-SPANGLED GRIN
Toronto Star, Tuesday, March 1, 2005 [Link below extract]

Extract:

"For Keltner the typical American smile is best represented by Tom Cruise. His smile is big and open, conveying warmth and genuineness. The typical British smile can be found in Prince Charles, Keltner said. His smile is also warm, and it conveys happiness but also a sense of decorum and considerateness.

On the surface, the two smiles may look the same. But there is a fairly subtle distinction at play — one that only a trained observer can detect, Keltner said.

Americans tend to smile without inhibition. The grins are big, open and more expressive. There is no muscle action constraining the mouth. It all starts with the "zygomatic major muscle" that pulls the lip corners up, he explained. An American smile is often referred to as the "Pan Am smile," but can also include the muscles around the eyes — the orbicularis oculi — crinkling to indicate warmth and happiness.

The British tend to smile in a slightly different way, one that conveys a sense of modesty and deference, said Keltner, who has studied and analyzed the 43 facial muscles used to express emotion.
-----------------
It was only when challenged recently by a British journalist to see if he could differentiate between the two nationalities and their smiles that he found he could — with almost 100 per cent certainty.

http://snipurl.com/d546