  Humans are fundamentally social. They have progressively dominated their
environment by the strength and creativity provided by and within their
grouping. It is well recognised that human groups are highly structured, and
the anthropological literature has loosely classified them according to their
size and function, such as support cliques, sympathy groups, bands, cognitive
groups, tribes, linguistic groups and so on. Recently, combining data on human
grouping patterns in a comprehensive and systematic study, Zhou et al.
identified a quantitative discrete hierarchy of group sizes with a preferred
scaling ratio close to $3$, which was later confirmed for hunter-gatherer
groups and for other mammalian societies. Using high precision large scale
Internet-based social network data, we extend these early findings on a very
large data set. We analyse the organisational structure of a complete,
multi-relational, large social multiplex network of a human society consisting
of about 400,000 odd players of a massive multiplayer online game for which we
know all about the group memberships of every player. Remarkably, the online
players exhibit the same type of structured hierarchical layers as the
societies studied by anthropologists, where each of these layers is three to
four times the size of the lower layer. Our findings suggest that the
hierarchical organisation of human society is deeply nested in human
psychology.
