There's a guy in Oslo (Pål Kristian Eriksen) who's just finished/gotten his doctorate in typological linguistics. His dissertation is on "to be": which languages have a separate word for it, which languages don't, and why. Unfortunately, his uni the University of Oslo isn't too fond of the riffraff (that is: anyone not at the university of Oslo) paving on their precious dissertations[*] so I don't know if there exists an electronic copy at all (it's only 2006 after all, gotta wait another century). Therefore I'll provide a summary of the published summary, in English even. Basically: languages which inflect the verb itself for present and preterite/past, will also have a verb for "to be". Examples include most IE-languages. Languages which use some other way to show time, don't have a verb for "to be". Examples include Chinese. The reason why "to be" is needed is because you can't add a particle/word meaning "not" directly to a noun used as a predicate, you need a buffer-word of some sort, hence "to be". I haven't managed to get hold of the dissertation itself so beware of the above being a summary of a summary of no doubt a summary. [*] <rant>In general, publicizing things beyond the minimum necessary to get a PhD seems to be beyond the pale, or maybe there are too few journals? The n hundreth higher education reform might change things but I don't think the old prof.s really want to have to write something once a year that may be read by potential riffraff... or is it just that the human(e) arts or as they are called here, humaniora, are supposed to publish long and rarely instead of short and often?</rant> t.