Why are female marathon runners given a fifteen minute head start?

I want to know why female marathon runners are given a fifteen minute head start. Is it to compensate? Or is it to make it more exciting and because the men get an extra prize if they beat the women?|||I believe the idea is that men are faster and have more stamina and therefore women get the head start. Probably archaic in design but that is what they have done for as long as I can remember.