The mystery of polygamy

The economic literature on marriage identifies a number of benefits of marriage and discusses mechanisms that cause societies to prefer certain marital structures such as polygamy or monogamy. In principle, however, these benefits and mechanisms might lead societies towards polyandry and even cenogamy. The rareness of polyandry and the absence of cenogamy, however, clearly indicate that important aspects of marriage are omitted. This paper argues that the reproductive nature of marital arrangements must be taken into account when analyzing the foundations of marriage. Monogamy always achieves efficient parental investments in offspring. For polygamous arrangements this might be often true. It fails, however, in polyandry because paternity cannot be established with certainty. Cenogamy is shown to be an unstable arrangement.