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.