Of Shades and Shadows: Duplication and Divergence

Words occasionally undergo duplication. This may happen in an inflected language if different grammatical forms of the same lexical item accumulate so much differences that speakers start regarding them as representing different units. For example, English shade and shadow used to be the same word, Old English (OE) sceadu, a feminine noun with oblique forms such as gen.sg. sceadwe (or sceaduwe, with a “parasitic” vowel). This inflectional pattern was somewhat irregular and restricted to just a handful of feminines (which happened to share some peculiarities explained by their earlier history). A speaker of Old English would normally have expected a genitive form like *sceade, without a superfluous /w/. It must have been tempting to re-interpret sceadwe as a case-form of a different (though closely related) word. In Middle English (ME) times we already have two different lexical items, shade and shadwe (the latter with spelling variants such as shadewe or shadowe). Although virtually synonymous (their meanings overlapped more that they do today), they were clearly two separate entries in the ME lexicon.

Shade and shadows in the streets of Vienna

The contrast soon increased as ME /a/ became lengthened whenever it was followed by a single consonant plus a reduced vowel (which the final -e was at the time). Eventually the weak vowel dropped out, but the lengthening persisted. Early in the 15th c. the pronunciation of shade was /ʃaːd/. As a result of the so-called Great Vowel Shift, which operated in the following decades, it developed into /ˈʃɛːd/, the ancestor of the modern forms (/ˈʃeɪd/ in the mainstream varieties of English, but with a number of dialectal variants). Meanwhile, the variant shadwe kept an inherited short vowel, becoming Modern English /ˈʃædəʊ/ (or something similar, depending on the accent). Today, both shade and shadow double up as verbs (to shade versus to shadow), and they did so already in Chaucer’s times. OE sceadwian ‘cover with shadow’ can only account for to shadow, so to shade must be an innovation based on the shorter variant of the noun.

A pair of related synonyms is unlikely to survive in the long run. One of them will eventually outcompete the other either because speakers have a reason to favour it consistently or because (even if there is no consistent bias) in a finite-size speech community random drift sooner of later eliminates one redundant variant. But there is a way in which duplicated words can escape extinction: they may develop different meanings or different grammatical functions. Today shade means ‘darkness caused by the screening of light’, ‘something that shuts out light’, or ‘degree of a colour, nuance (of anything)’, while shadow means ‘dark image cast by a body that blocks light’ or, figuratively, ‘hint, trace’ (as in the shadow of a doubt). They are rarely interchangeable. They have escaped direct competition by undergoing functional specialisation. That’s why they are still alive, a thousand years after they started drifting apart.

Duplication followed by divergence is a common motif in linguistic evolution, and I intend to return to it soon.