The Definitive Book of Body Language

The Magic of Smiles and Laughter

that distinguish these smiles from genuine ones. When a smile

is genuine, the fleshy part of the eye between the eyebrow and

the eyelid - the eye cover fold - moves downwards and the end

of the eyebrows dip slightly.

Smiling Is a Submission Signal

Smiling and laughing are universally considered to be signals
that show a person is happy. We cry at birth, begin smiling at
five weeks and laughing starts between the fourth and fifth
months. Babies quickly learn that crying gets our attention -
and that smiling keeps us there. Recent research with our
closest primate cousins, the chimpanzees, has shown that
smiling serves an even deeper, more primitive purpose.
To show they're aggressive, apes bare their lower fangs,
warning that they can bite. Humans do exactly the same thing
when they become aggressive by dropping or thrusting
forward the lower lip because its main function is as a sheath
to conceal the lower teeth. Chimpanzees have two types of
smiles: one is an appeasement face, where one chimp shows
submission to a dominant other. In this chimp smile - known
as a 'fear face' - the lower jaw opens to expose the teeth and
the corners of the mouth are pulled back and down, and this
resembles the human smile.

A primate

'fear face' (left)

and a primate

'play face'