From Abram:
I suggest a new measure of humans (or at least a reasonable proxy for
uniqueness): entropy

Entropy is a measure of information or how much something can be
compressed. Essentially we could find a standard coding system for
multiple aspects of a man, write it out using plain-text and then take
the entropy of the characters, the words, the n-grams and use that to
measure uniqueness. A high entropy would suggest you have a lot of
information and are not that compressible so perhaps you are in fact
unique.

This could leading to an auto-mated dating revolution.