The letter "j" was first distinguised from "i" in the middle of the 16th century by the philosopher Pierre de la Ramée. In fact, a long "i" was used by the Romans, and an "i" with a long tail was often used by writers in the middle ages.
I was just thinking that it's a shame that character-evolution is probably all but over now that everything's being digitised. Not only are we losing the joy of handwriting—from Shakespeare's Signature to Dickinson's Dashes—but also those things that take centuries to evolve, such as the ampersand.
Oh well. Perhaps digital paper will become fashionable.