Communication !
Growing up has various signs.. from the way our body changes to how our language evolves... But the more our language evolves, the lesser we seem to use words effectively. Like Pluto (in Dil Dhadakne Do ) comments on this strange paradox, humans have all the tools to communicate all their thoughts (clearly and effectively) , they choose to (more often than not) mince words and resort to subtle signs. Sigh ! How much easier life would've been if we'd use the faculties nature has blessed us with !