What strange behavior? I don't know of any human activity which can be called strange. Strange would be something a human would not / could not do or think -- but if a human thinks/does it, then it can be done by a human, so it isn't strange.
The question is utterly absurd?
The more relevant question should be, why has the superstition of "strange behavior" gained such widespread acceptance? Any doctrine of the existence of "strange behavior" can defend itself only by recourse to pure Platonism.
Carrol