We have all descended from our common ancestors, the apes. The same is true in relation to the castes. [One might try to argue that] the forefathers of the Bráhmańas were the ape-Bráhmańas and the forefathers of the Kśatriyas were the ape-Kśatriyas; but that just isn’t so. As apes do not have any particular caste, the present-day caste differences are all hypocrisy and maliciousness. You should remove even the least vestige of these nonsensical notions. You must not give credence to such things.
So Shiva taught Bhaerava. Then He thought: “If I teach this only to my son; that is, if my son alone knows this secret spiritual cult, this great asset for humanity, and my daughter remains ignorant, then fifty per cent of the society will remain a burden for the other fifty per cent; that is, the women will remain a burden for the men, and the movement of the men also will be greatly impeded.” Even in those days, seven thousand years ago, Shiva thought in this way. “If I only give the strength and responsibility to carry the burden to my son, Bhaerava, that will not be good. I will also have to give some of the responsibility to my daughter, Bhaeravii.” And that is what He did. And since that day, any woman practising Tantra is known as Bhaeravii.
Shrii Shrii A'nandamu'rti
Discourses on Tantra II