In some cases, the increase in body size may represent a passive, rather than an active, trend. In other words, the maximum size increases, but the minimum size does not; this is usually a result of size varying pseudo-randomly rather than directed evolution. This does not fall into Cope's rule "sensu stricto", but is considered by many workers to be an example of "Cope's rule "sensu lato"". In other cases, an increase in size may in fact represent a transition to an optimal body size, and not imply that populations always develop to a larger size.