Writers 
Organizationally, gender dualism divides society into two basic and complementary populations—the male and the female—to which functions are assigned. By their designated spheres of activity, by their reciprocal rights and responsibilities, by their competition and cooperation, the male and female groups created by these assigned functions help to integrate society into a structured, functional whole.
In African pre-industrial societies, there are defined male and female spheres in the affairs of the family as well as in those of the polity. Such spheres are sometimes demarcated by taboos and other psychological barriers, as well as by sanctions for acts of trespass. Of course, there are also spheres which are not zoned exclusively to either gender. However, in a complementary show of flexibility and rigidity, even the strongest gender taboo may be broken in exceptional circumstances, as we shall see.
As an example of gender dualism in economic affairs, consider the typical division of functions in Yoruba towns. Zoned to men are plantation farming, hunting, fishing, and long-distance trading. These are activities which take place in the unsafe areas beyond the town walls. Within the safety of the town walls, women engage in food processing and local trading.
In the technical crafts, which also are conducted in town, some are in the male sphere: iron smelting, smithing (iron, gold, copper, etc.), tanning, carving, divination, drumming, etc. Others are in the female sphere: spinning, dyeing, pottery, bead making, etc.
This division of functions conforms to the general African pattern where, as Cheikh Anta Diop remarked, "contrary to the legend the least onerous tasks are reserved for women." That notwithstanding, the dividers between these male and female spheres are not impenetrable. Indeed, any woman, if keen enough, could enter and shine in any field, including divination, plantation farming, and long-distance trading, as is reported from the Yoruba town of Okuku.
In the area of supervisory responsibility for the well-being of others, there are examples of gender dualism with remarkable reciprocity. For instance, among the Igbo, it is the responsibility of the males of a lineage, the Umunna, to keep an eye on the welfare of a married sister, and to bring her back to the natal home if she is mistreated by her husband. In reciprocation, it is the responsibility of the daughters of the lineage, the Umuada, to keep an eye on the welfare of a brother and ensure that he is not done in by his wife. This oversight function climaxes at burial ceremonies where the Umuada interrogate the widow of the deceased to ascertain that she had no hand in the death of their brother.
In cultural activities, gender dualism reigns. As a rule, cultural activities are organized in single-gender groups. Besides the male-only and the female-only groups in singing, dancing, etc., there are also cases of gender specialization in different genres of the same art. For instance, among the Yoruba of Okuku town, the job of keeping historical memory is divided by gender: Oríkì, praise poems which honour outstanding persons and places, is in the keep of women, while its complementary genre, Ìtàn, historical narrative, is in the keep of old men.
An example of complementary gender dualism in political roles is provided by Kemet, where the office of the Pharaoh was reserved for males, but the transmission of the right to Pharaohship was through the daughter of the Pharaoh. Any man could become a Pharaoh, but only by virtue of being married to a daughter of the Pharaoh. Even the son of Pharaoh could only become a Pharaoh by marrying a daughter of his father, hence the extraordinary Kemetic tradition of royal incest. But even here, with the characteristic dualism of flexibility within rigidity, exceptional women became pharaohs in exceptional times and circumstances. Such were Nerfreti of the 6th dynasty and Hashepsowe of the 18th dynasty.
This pharaonic transmission of political rights through females is not atypical in Africa. As Cheikh Anta Diop noted, where ancient matrilineal practices have "not been altered by external influences (Islam, etc.), it is the woman who transmits political rights. This derives from the general idea that heredity is effective only matrilineally."
