The polygamy is a word that comes from Greece and if you translate it, the meaning will be “often married”. The polygamy has an interesting meaning where the marriage is done with more than just two partners as it happens at most societies. In most countries out there the polygamy is not a practice that is tolerated and the laws are usually making it illegal.

Two psychologists testified in the findings, describing possible outcomes that can be expected from polygynous mating arrangements. Dr. Henrich explains the cold mathematics of polygyny: This illustration reveals the underlying arithmetic that can result in a pool of low-status unmarried men. Imagine a society of 40 adults, 20 males and 20 females. Suppose those 20 males vary from the unemployed high-school drop-outs to CEOs, or billionaires. Lets assume that the twelve men with the highest status marry 12 of the 20 women in monogamous marriages. Then, the top five men (25% of the population) all take a second wife, and the top two (10%) take a third wife. Finally, the top guy takes a fourth wife. This means that of all marriages, 58% are monogamous. Only men in the to 10% of status or wealth married more than two women. The most wives anyone has is four.

The degree of polygynous marriage is not extreme in cross-cultural perspective, but it creates a pool of unmarried men equal to 40% of the male population who are incentivized to take substantial risks so they can eventually participate in the mating and marriage market. This pattern is consistent with what we would expect from an evolutionary approach to humans, and with what is known empirically about male strategies.

Marriage civilizes men: Dr. Henrich begins with an ample body of research that shows marriage makes men much less likely to commit crimes such as murder, robbery and rape. One such study showed that marriage reduced a man€™s likelihood of committing a crime by 35%. This study was particularly compelling as it did not simply compare the criminality of married and unmarried men, but used longitudinal data to track boys from a reform school from age 17 to 70. In this study, crime rates not only decreased when those men were married, but increased when they divorced or were widowed. Other studies are consistent in showing the association between monogamous marriage and decreased male criminality. He cites studies (not listed in the decision) that examine the relationship between crime and 1) the degree of polygyny across countries, 2) the percentage of unmarried males, and 3) sex ratio of males to females in countries like China, as a result of their one-child policy and a desire to have sons and abort / kill daughters.

Men in polygynous societies aren’t very good fathers: Another major predicted consequence of widespread polygyny is decreased male parental investment. The underlying theory is that since married men would remain perennially in the marriage market, high-status men could choose to invest their resources in acquiring more wives rather than investing in their children. Similarly, the pool of unmarried men would be forced to invest their resources in attempting to improve their status so as to improve their chances of finding a bride.

As support for this proposition, Dr. Henrich relied on findings from 19th century census data from Mormon polygynous communities and from contemporary studies of African societies.

The study of historical Mormon polygynous communities showed that the children of poorer men (from the bottom 16% of wealth in that community) had higher survival rates than those of the richest men in the community (from the top 2%). The poor men had an average of 6.9 children survive until age 15. For the rich men, despite having more total offspring than the poor men and having over 10 times the wealth, only 5.5 children survived until age 15 on average. Dr. Henrich concludes that this data supports the idea €œthat in polygynous systems poor, but married, men will have no choice but to invest in their offspring while rich, high-status men will invest in getting more wives.

Allegedly, when the competition for brides go up, men try to secure brides at younger ages. Males learn the value of their female relatives, start treating them like an economic resource, and exert control of women’s reproductive lives. Competition drives men to use whatever connections, advantages, and alliances they have in order to obtain wives, including striking financial and reciprocal bargains with the fathers of daughters (this is the very common practice of bride price). Once girls and young women become wives, older husbands (and brothers) will strive to €œprotect their young wives from other males (to guarantee paternity of any offspring), and in the process dampen women’s freedoms and exacerbate inequality.

Polygamy being illegal is important because in some circles, marriage is viewed as antiquated or quaint or tainted with religion or stayed or defended irrationally. But we would be wise to examine long-standing traditions and see if there might not have been some reason for their continued existence. We are entering a brave new world of sexual dynamics, which will inevitably be a mixed bag of outcomes, some good and some bad. And the most important social dynamic will not be what happens to gay marriage, but what happens to monogamy under the attack of modernity.