  Distinctive linguistic practices help communities build solidarity and
differentiate themselves from outsiders. In an online community, one such
practice is variation in orthography, which includes spelling, punctuation, and
capitalization. Using a dataset of over two million Instagram posts, we
investigate orthographic variation in a community that shares pro-eating
disorder (pro-ED) content. We find that not only does orthographic variation
grow more frequent over time, it also becomes more profound or deep, with
variants becoming increasingly distant from the original: as, for example,
#anarexyia is more distant than #anarexia from the original spelling #anorexia.
These changes are driven by newcomers, who adopt the most extreme linguistic
practices as they enter the community. Moreover, this behavior correlates with
engagement: the newcomers who adopt deeper orthographic variants tend to remain
active for longer in the community, and the posts that contain deeper variation
receive more positive feedback in the form of "likes." Previous work has linked
community membership change with language change, and our work casts this
connection in a new light, with newcomers driving an evolving practice, rather
than adapting to it. We also demonstrate the utility of orthographic variation
as a new lens to study sociolinguistic change in online communities,
particularly when the change results from an exogenous force such as a content
ban.
