Interesting indeed. There seems (to me) to be a comprehensive set of contrasts and distinctions:
two halves,
a single whole,
asleep, vs awake,
male (outer), female (inner),
3rd eye (1 + 1 = 2 where the 2 is something within a context that is greater than the sum of it's parts),
square chin vs ball chin,
the arch,
the various directions,
calm unconcern (male lips) vs slight amusement (female lips),
direct perception (female looking directly at the viewer)
inner female emerging (or at least about as prominent as the outer) male,
rough (male features) vs smooth (female features)
color (earth toned, yet seemingly half way between light and dark)
Even more can be seen
And all blended into a rounded kind of shape suggestive of a self-reflective totality (inner awareness as central pivot point?) I don't know...just my thoughts, fwiw.
Edit: clarity