Why is it that in some parts of the world, women are overburdened with many tasks, while men are displaced from many of their roles?

Chapter 3 (Gender and Family, Overburdened Women and Displaced Men).Why is it that in some parts of the world, women are overburdened with many tasks, while men are displaced from many of their roles? Why can’t the men just take on some of the tasks being done by women?