Another informative post.
One thing to add:
"Another, deeper answer stems from evolutionary reasons. Human survival depends on other people-whether we need help from them or we should beware of them. One has to understand other people and decipher their behavior at high speed so the brain may be wired to identify other people at every opportunity: the accidental mistake of recognizing a fake face in a tree trunk is not as severe as failing to recognize a real face hiding in the bushes."
Humans are experts in facial recognition. This special skill is a survival evolutionary necessity.
We are able to identify a face that we saw once on the street,
to classify by facing the people who endanger us and by facial expressions to get a great deal of information about the person.