And Tolkien was right, of course: words arise into language in order to define something, so for the word 'elf' to be so prevalent through so many ancient languages (and modern ones!) the word must have referred to something in physical existance. It would be most interesting if one could find out exactly when the word first began to be used. I mean, the timing of it would possibly indicate the emergence of whatever prompted the rise of the word into speech. For example, the words 'astronaut' and 'cosmonaut' were unknown in any language before oh, roughly, the 1960's. It was only after the space race started, and we began to put men into space capsules on a routine basis that the terms became widespread in use. Following the logic of this, if we could find out when the word 'elf' first made its appearance into daily speech, we could then begin seriously to search for what caused its appearance.

The word would have had to describe a physical set of conditions that were 1) previously unknown, 2) widespread among humans of differing cultures, and 3) sufficiently important to make it necessary to define it for then-current purposes. It's possible that it referred to a new form of technology and the practitioners of it, rather than a genetically distinct 'race'. But then, where did those pointy ears come from???