The short version: HUMANS HAVE NO NEED FOR HUMAN FACES ANYMORE.

When you see a colon and a parentheses, you know exactly what it means. The smiley face has become ubiquitous online, and psychologists have even looked into the ways it’s used in emails. Now, researchers say that not only do we know what the little :) means, but we actually perceive it the same way we perceive an actual human face. (Via.)

That's from Smithsonian. And from ABC:

"Emoticons are a new form of language that we're producing," says researcher, Dr Owen Churches, from the school of psychology at Flinders University in Adelaide, "and to decode that language we've produced a new pattern of brain activity." (Via.)

Okay, so maybe me saying humans have no need for human faces anymore was kind of exaggerating (HOW ELSE WOULD WE EAT), but the fact our brains now have the same response to :) as we do when seeing an actual human being smile is kind of... I don't know? There isn't really an emoji for neat and creepy at the same time. :/