The word patriarchy originates from the Greek word πατριάρχης. It combines πατήρ (patēr, "father”) and ἀρχή (arkhē, "domination, authority, sovereignty"). Historically, it designates the autocratic rule of the male head of a family. In the words of sociologist Sylvia Walby, patriarchy is a “system of social structures and practices in which men dominate, oppress, and exploit women." In this system, political leadership, moral authority, and property rights are vested in men. With regard to the emergence of patriarchy, one point that is common among anthropologists, archaeologists, and evolutionary psychologists is that it started with the advent of social and technological advancement, viz., agriculture and domestication, around 4000 BCE. After the start of agriculture, human beings turned from hunter-gatherers to producers of food. They no longer needed to relocate. They started domesticating and using animals in agriculture. To produce more resources and protect their resources, they had to wage wars against the invading tribes. Wars cost the lives of men. Since women did not participate in war, as they were considered weak, they had to maintain the population through the reproduction of male children. Women who refused to produce children or who were infertile were condemned as unnatural, and men who feared wars were mocked. Even in the 21st century, the patriarchal society prefers male babies. Aristotle, the famous Greek philosopher, maintains that women are morally, intellectually, and physically inferior to men. He believes that women, like other objects, are the property of men. Moreover, he claims that in the social system, women’s role is to reproduce and serve men in the household. He justifies the male imperium of women as natural and virtuous. Confucianism, the official religion of China in the Han dynasty, promoted gender roles in society. The confusion text Three Obedience and Four Virtues values a woman for her loyalty and obedience to male members of her family. It says that an obedient woman has to obey her father before marriage, her husband after marriage, and her first son in the case of widowhood, and a virtuous woman must practice sexual propriety, proper speech, modest appearance, and hard work.