Universal 566: Du (2 & 3 person) ⇒ Du (1 person)

Original: If 2nd and 3rd Person differentiate a Dual, so does (with more than chance frequency) 1st (but not vice versa).
Standardized: IF 2nd and 3rd person differentiate a dual, THEN so does (with more than chance frequency) 1st (but not vice versa).
Keywords: pronoun, personal pronoun, number, dual, 3rd person, 2nd person, 1st person
Domain: inflection
Type: implication
Status: achronic
Quality: absolute
Basis: languages in Humboldt 1830, including Basque (isolate), Greenlandic (Eskimo-Aleut), Saami (Uralic), Tahitian, Malay (both Malayo-Polynesian), Indo-European (e.g. Sanskrit, Ancient Greek), Semitic languages, American languages (e.g. Quechua, Totonaca, Huasteca, Mapuche, Tamanaca, Chayma)
Source: Humboldt 1830, as interpreted in Plank 1989: 302; Plank 1994b: 232

Counterexamples: Ancient Greek (Indo-European), Classical Arabic (Semitic, Afro-Asiatic) and Aleut (Eskimo-Aleut) (Plank 1989: 303).

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