Common mating or reproductively motivated systems include monogamy, polygyny, polyandry, polygamy and promiscuity. In most tinamou species, the males practice simultaneous polygyny and the females sequential polyandry. Other mating systems, including polygyny, polyandry, polygamy, polygynandry, and promiscuity, also occur. Their mating systems are highly variable and can include monogamy, polygyny, and polyandry. In some species, such as redlip blennies, both polygyny and polyandry are observed. Several rodent species have flexible mating systems that can vary between monogamy, polygyny and promiscuity. The mating system of pinnipeds varies from extreme polygyny to serial monogamy. CE, both monogamy and polygyny occurred. Period drama and historical novels frequently refer to the former culture of polygamy (usually polygyny). They were largely but not completely successful in encouraging Shuar to abandon polygyny for monogamy. An explanation for why polygynous systems persist is explained by the polygyny threshold model. The Fon culture is patrilineal and allows polygyny and divorce. Parasitism of preexisting nests appears to be the best explanation of polygyny. They argued that misogyny is a better explanation than polygyny. Although many countries have laws restricting or banning polygyny, it is still practiced illegally.