Nicholas Evans for Encyclopaedia of Language and Linguistics

Dyad constructions provide a way of referring to pairs or groups of people based on the social relationship they share, but so far they have escaped systematization within general linguistics. This article defines and exemplifies the various kinds of dyad construction, distinguishes them from related categories (reciprocals, duals, associative duals, family group classifiers, additive co-compounds), and examines their geographical distribution. Dyad constructions form, from kin and other relational expressions, terms denoting pairs of the type ‘uncle and nephew(s)’, ‘mother and child(ren)’. They may be formed by morphological derivation – cf Kayardild (Australian) ngamathu ‘mother’; ngamathu-ngarrba ‘mother and child’ – or may be unanalyseable lexical roots, such as Mianmin (Papuan) lum ‘father and child’. Dyad constructions may be related, formally, to reciprocals, duals, or proprietive or possessive constructions, or may involve dedicated morphemes or unanalyseable lexical stems. They have a skewed geographic distribution, with a hotbed in Oceania and the Western Pacific, sporadic occurrence in North, Central and East Asia and western North America, and only occasional attestation elsewhere (Amazonia; the European periphery, and Southern Africa). 1. Initial definition and exemplification Dyad constructions denote relationally-linked groups of the type ‘pair/group of brothers’, ‘mother and child(ren)’, ‘teacher/student pair’ (see Evans 2003a for sources of all unreferenced data or terminology in this article). They may be formed by morphological derivation, as with Kayardild (Australian) ngamathu-ngarrba ‘mother and child’ < ngamathu ‘mother’, or they may be unanalyseable lexical roots, such as Mianmin (Papuan) lum ‘father and child’ (Smith & Wesson 1974). Though they most commonly refer to pairs, as in the above examples, they may also refer to larger groups, e.g. Mianmin lum-wal ‘father and children’. Though the above languages have dedicated dyad forms, it is more common for dyadic constructions to overlap formally with other categories, most commonly reciprocals, proprietive or possessive constructions, or pair markers (§3). Where a dual-plural contrast exists, the dual dyad is usually formally unmarked (§4). Dyad constructions display a notably skewed geographical distribution, being concentrated in the language families of the Western Pacific, with only scattered occurrences elsewhere (§5). Typically, languages with dyad constructions can form them both from symmetric (self-converse) terms like English ‘cousin’ (X is Y’s cousin ́ Y is X’s cousin), and from asymmetric terms like English ‘mother’ (X is Y’s mother <-/-> Y is X’s mother), using the same constructional pattern. Kayardild ngamathu-ngarrba above has an asymmetric root; while kularrin-ngarrba ‘brother and sister pair’, derives from the symmetric kularrin-da ‘opposite sex sibling’. Although, cross-linguistically, there is