Is English the only one that does this? I note that in most languages that distinguish between "he" or "she" (Chinese for example, uses one pronoun for the third person singular) they usually have grammatical gender too. Most languages, it seems, that do not have grammatical gender (e.g. Chinese and Malay) will not distinguish between "he did it" or "she did it either". English lost grammatical gender fairly recently. Can one assume that looking at the trend of history it's only a matter of time before we use one word for both "he" and "she"? Some interesting cases I suppose are the Japanese honorifics system (which I assume declines for the gender of audience and speaker) and Vietnamese which seems to use third-person for self-reference a lot.