And, even given an unlimited budget, I can't think of any other method that essentially allows researchers to travel back in time and directly observe participants behavior in the past.
Ngisho noma inikezwa isabelomali esingenamkhawulo, noma kunjalo, angikwazi ukucabanga nganoma iyiphi enye indlela evumela ukuthi abacwaningi babuyele ngesikhathi futhi babone ngokuqondile ukuziphatha kwabahlanganyeli esikhathini esidlule.