Blood as Kinship and Covenant

Separate from sacrifice, blood also stands across many cultures for a bond stronger than ordinary agreement: blood relations are treated as a different order of obligation than chosen ones in most kinship systems, and rites of blood brotherhood, in which participants mix or exchange blood to create a kinship-like tie between people not otherwise related, appear independently in societies from parts of Africa and Central Asia to the American frontier. The logic is the same wherever it appears: sharing blood is treated as sharing the substance of life itself, and an oath sealed that way is read as harder to break than a merely spoken one.

Menstrual blood carries yet another, frequently more contested set of associations, treated in some traditions as ritually powerful and in others as polluting, sometimes both at once within the same culture, a divide anthropological studies of menstrual taboo have documented at length rather than resolved into one universal reading.