  Wikipedia is the largest existing knowledge repository that is growing on a
genuine crowdsourcing support. While the English Wikipedia is the most
extensive and the most researched one with over five million articles,
comparatively little is known about the behavior and growth of the remaining
283 smaller Wikipedias, the smallest of which, Afar, has only one article. Here
we use a subset of this data, consisting of 14962 different articles, each of
which exists in 26 different languages, from Arabic to Ukrainian. We study the
growth of Wikipedias in these languages over a time span of 15 years. We show
that, while an average article follows a random path from one language to
another, there exist six well-defined clusters of Wikipedias that share common
growth patterns. The make-up of these clusters is remarkably robust against the
method used for their determination, as we verify via four different clustering
methods. Interestingly, the identified Wikipedia clusters have little
correlation with language families and groups. Rather, the growth of Wikipedia
across different languages is governed by different factors, ranging from
similarities in culture to information literacy.
