A watan Mayu na 2016 wani nazari da Marcia Ponce de León da Christoph Zollikofer a Jami'ar Zurich ta Switzerland suka jagoranta, inda suka yi nazari a kan kugun mutane 275 maza da mata na rukunin shekaru daban-daban, sun bayyana cewa kugun mace yana sauyawa a lokacin rayuwarta.
