section_path: Society/Kinship
section_name: Kinship
paragraph_text: Kinship
  
  All human societies organize, recognize and classify types of social relationships based on relations between parents, children and other descendants (consanguinity), and relations through marriage (affinity). There is also a third type applied to godparents or adoptive children (fictive). These culturally defined relationships are referred to as kinship. In many societies, it is one of the most important social organizing principles and plays a role in transmitting status and inheritance. All societies have rules of incest taboo, according to which marriage between certain kinds of kin relations is prohibited, and some also have rules of preferential marriage with certain kin relations.
  
  Pair bonding is a ubiquitous feature of human sexual relationships, whether it is manifested as serial monogamy, polygyny, or polyandry. Genetic evidence indicates that humans were predominantly polygynous for most of their existence as a species, but that this began to shift during the Neolithic, when monogamy started becoming widespread concomitantly with the transition from nomadic to sedentary societies. Anatomical evidence in the form of second-to-fourth digit ratios, a biomarker for prenatal androgen effects, likewise indicates modern humans were polygynous during the Pleistocene.