Causal evidence for social group sizes from Wikipedia editing data

Human communities have self-organizing properties in which specific Dunbar
Numbers may be invoked to explain group attachments.  By
analyzing Wikipedia editing histories across a wide range of subject
pages, we show that there is an emergent coherence in the size of
transient groups formed to edit the content of subject texts, with two
peaks averaging at around $N=8$ for the size corresponding to
maximal  contention, and at around $N=4$ as a regular team. These
values are consistent with the observed sizes of conversational groups, as
well as the hierarchical structuring of Dunbar graphs.  We use
the Promise Theory model of bipartite trust to derive a scaling law
that  fits the data and may apply to all group size
distributions, when based on attraction to a seeded group process.
 In addition to  providing further evidence that even
spontaneous communities of strangers are self-organizing, the results have
important implications for the governance of the Wikipedia commons and for
the security of all online social platforms and associations.