The brain recognizes :-) as smiling face emotion.

http://www.independent.co.uk/news/science/happy-days-human-brain-now-registers-smiley-face-emoticon-as-real-facial-expression-9117473.html

Every change, including the latest trends on emotional signs such as :-), or :( are small steps toward the change or evolution of language. From the linguistic point of view language evolve influenced from a diverse social and environmental factors.