A number of works have explored expletive negation in clause-linkage constructions. Most of them have shown that
this type of negative marker can be omitted from the adverbial clause without affecting the interpretation holding between
clauses. The study shows, based on the analysis of natural discourse data, that expletive negation has developed an intriguing
discourse function in three types of ‘until’ constructions in Huasteca Nahuatl: ‘not…until’ constructions, scalar additive ‘until’
constructions, and beginning-to-end constructions. When the negative marker amo appears in the ‘until’ clause,
the proposition should be characterized as expressing surprise. When it is absent from the ‘until’ clause, the proposition does
not express surprise. This function of the expletive negative marker amo does not appear in elicited sentences,
but only in spontaneous speech. It is proposed that Huasteca Nahuatl developed expletive negation in ‘not…until’ constructions due
to contact with Spanish. However, the development of expletive negation in scalar additive ‘until’ constructions and
beginning-to-end constructions is an internally motivated development in Huasteca Nahuatl that cannot be attributed to
Spanish.