The theory of language change has worked primarily with four basic language profiles: generational change, age-grading, communal change, and stability (Sankoff 2006; Wagner 2002). This paper focuses on age-grading. The explanations put forward in the sociolinguistic literature to explain why and how age-grading occurs are primarily social. These often rely on the study of adolescents and on the theory of the linguistic market (Bourdieu and Boltanski 1975; Sankoff and Laberge 1978; Wagner 2002; Sankoff 2006). Following the distinction between chronological, social and biological ageing (Eckert 1997: 156; Hejná and Jespersen 2021), this study provides an overview of hormonal and non-hormonal biological factors which should also be taken into account, focusing on phonetic variation. Considering biological factors is important in order to avoid interpreting cases of biological age-grading as (solely) social in nature, and as cases of generational change rather than age-grading to begin with. In order to highlight the potential for interactions between social and biological age-grading, we therefore also demonstrate how teasing the two apart can become challenging.
