London Guardian 
Aug 14, 2012
It is just a number – 1.618 – but to its devotees the ratio expresses aesthetic perfection, and can be found wherever there is beauty.
For example, they argue that of all the rectangles in the world the most pleasing to the eye has a ratio of length to width of 1.618.
And of all the smiles in the world, they maintain that the most beautiful have their central incisors 1.618 wider than their lateral incisors, which are 1.618 wider than their canines, and so on down through the molars.
There are web pages  devoted to where else on the human face you can find the golden ratio, which is also known as the golden section, golden proportion or golden mean.