wives may live in separate households. They can thus be described as a "series of linked nuclear families with a 'father' in common". Polyandry Incidence Polyandry, the practice of a woman having more than one husband at the one time, is much less prevalent than polygyny. It is specifically provided in the legal codes of some countries, such as Gabon. Polyandry is believed to be more common in societies with scarce environmental resources, as it is believed to limit human population growth and enhance child survival. It is a rare form of marriage that exists not only among poor families, but also the elite. For example, in the Himalayan Mountains polyandry is related to the scarcity of land; the marriage of all brothers in a family to the same wife allows family land to remain intact and undivided. If every brother married separately and had children, family land would be split into unsustainable small plots. In Europe, this outcome was avoided through the social practice of impartible inheritance, under which most siblings would be disinherited. Types Fraternal polyandry was traditionally practiced among nomadic Tibetans in Nepal, parts of China and part of northern India, in which two or more brothers would marry the same woman. It is most common in societies marked by high male mortality. It is associated with partible paternity, the cultural belief that a child can have more than one father. Non-fraternal polyandry occurs when the wives' husbands are unrelated, as among the Nayar tribe of India, where girls undergo a ritual marriage before puberty, and the first husband is acknowledged as the father of all her children. However, the woman may never cohabit with that man, taking multiple lovers instead; these men must acknowledge the paternity of their children (and hence demonstrate that no caste prohibitions have been breached) by paying the midwife. The women remain in their maternal home, living with their brothers, and property is passed matrilineally. A similar form of matrilineal, de facto polyandry can be found in the institution of walking marriage among the Mosuo tribe of China. Serial monogamy Serial monogamy refers to remarriage after divorce or death of a spouse from a monogamous marriage, i.e. multiple marriages but only one legal spouse at a time (a series of monogamous relationships). According to Danish scholar Miriam K. Zeitzen, anthropologists treat serial monogamy, in which divorce and remarriage occur, as a form