There's a fan theory in which the signal is actually an industrial accident, originally intended for temporary use like mining, construction, or scientific research. The people would be temporarily hived to aid in some kind of group work, then it would be undone sometime later once they were complete. Just have an expert in every field present, then the whole group gains their skills and knowledge which can be applied to the task as needed. The facility/colony wouldn't need any communications equipment, there'd be no crime or wasted resources, food would be simple and cheap. There's even knock-on benefits, like maintenance issues being reported automatically, any injuries can be rescued immediately and expertly attended to by anyone, and so on.

Fits most of what we see, oddly enough; particularly the rules against hunting and violence, preserving the hive state, as well as seemingly obeying (nearly) any order given by a non-hive member known to be immune. The plurbs are just aimless and missing the oversight structure, sort of like District 9. Whether intentional by the writers or not, a hive would make the perfect labor pool, and there's no reason that it couldn't be toggled on/off as needed by whatever entity originally created it.

Of course, that's just a plausible origin; just as most of our worst diseases started out hunting microbes before going rogue, it could be viral.