i ponder this all the time. i always thought wen i was little that i was the only living human, and everyone else was robots trying to pretend that they were real but werent. very odd. then again i was a strange child at my age, and i was very smart for a youngin. i learned to say short sentences at about 8-9months old. for example"cookie now" lol. anyways i started having conversations at about a year. pretty starnge actually.