That is the conclusion of three Hebrew University professors in a report called "The Mystery of Monogamy." It is based on a study conducted in the African country of Ivory Coast.
Eric Gould is a Hebrew University economics professor and one of the authors of the report. He tells RFE/RL that the purpose of the research was to look at the correlation between polygamy and economic development, since all of the societies in which polygamy is practiced are developing countries, while monogamy is the common practice in all developed countries.
Gould says the overall impact of polygamy on developing economies is negative. "In general, wealthy men like lots of children and lots of wives. But the difference between developed countries and nondeveloped countries is how people get wealthy and a value of education in a society," he says. "So, in a nondeveloped country, men don't get wealthy through their education and through their human capital. They basically get land or another kind of wealth. They know their children are not going to get wealthy through education, and so forth. So, they prefer lots of children with a low level of human capital."
The authors of the research say that if a man gets wealthy through a good education, he is inclined to take an educated wife and invest more in his children because he knows that less-educated children have a lower chance of getting a good job.
The study says polygamy used to be practiced in the West but died out as the societies developed and education became a key to prosperity.
Having more than one wife was a widespread practice in pre-Christian and pre-Islamic societies. Nowadays, it still exists mainly in Thailand, sub-Saharan Africa, and in some other Islamic countries.
In predominantly Christian countries, the Mormons (the Church of Jesus Christ of Latter-Day Saints) have practiced polygamy since the sect's founding in the 19th century. Based in the western U.S. state of Utah, the practice was officially banned under pressure from the U.S. government in 1890, though it is still practiced by some breakaway Mormon churches.
About 30,000 excommunicated Mormons in Utah, Arizona, and other Western U.S. states still engage in polygamy, as well as about 1,000 people in Canada's British Columbia.
Central Asian countries and Azerbaijan have seen a boom in polygamy in recent years. Proponents of the practice say it is allowed in Islam, which allows a man to take up to four wives.
Gould says the study on polygamy showed that the correlation between polygamy and Islam is not as strong as the linkage between polygamy and the level of economic development.
"We do some empirical work using data from [Ivory Coast] in Africa," he says, "and you find there even within Christian communities that there is polygamy, and the predictions of our theory are relevant for them as well as for Muslims."
In 2000, Russia's eccentric ultranationalist politician Vladimir Zhirinovsky proposed polygamy as a novel solution to the country's demographic crisis. The leader of the Liberal Democratic Party proposed the country's family code be amended to allow men to take up to five wives. More wives, Zhirinovsky reasoned, would mean more babies, and thus boost Russia's shrinking population. After a brief debate in parliament, his scheme was dismissed.
In Tajikistan, the 1992-97 civil war resulted in a gender imbalance and subsequently led to an increase in polygamy.
In Kazakhstan, the parliament discussed the legalization of polygamy at the initiative of the League of Muslim Women of Kazakhstan, about five years ago. The league's leader, Amina Abdukarim Qyzy, suggested that polygamy would increase the country's population and "bring happiness to many men and women."
According to a survey conducted by Kazakhstan's daily "Express-K" in December, 40 percent of respondents said the legalization of polygamy was a good idea.
In Azerbaijan, there were discussions in January about legalizing polygamy. The main supporter was the leader of the Islamic Party, Gadzhi-Aga Nuriyev.
Legally, polygamy is still considered a criminal offense in Central Asia and Azerbaijan. But there has been a consistent increase in men taking more wives through nikah, or Islamic marriage. Nikah, however, has no legal force in the region's secular states. Therefore, in the case of divorce or the death of a husband, the second and third wives of the man and their children have no rights.
Sheikh Muhammad Sadyq Muhammad Yusuf, a prominent Islamic scholar in Uzbekistan, tells RFE/RL there are strict rules in Islam about polygamy. Only a man with substantial wealth is allowed to take another wife after getting permission from his existing wife or wives. He is required to treat all of them equally in terms of financial, sexual and general attention and to provide for their children.
The sheikh also says it would be wrong to believe the recent increase in polygamy is due only to Islamic revivalism. "Many men take more wives without meeting the requirements [of Islam]," he says. "This decision is not based on religion or on the rules that allow a man to marry several women. There are other, [sexual] reasons. It's very regrettable."
Observers say hard economic conditions force women to become second or third wives. But many men fail to provide their multiple wives and children with the same financial opportunities.
Gould says there are various ways to eliminate polygamy -- from simply banning it to creating better economic conditions for men and women.
"One thing is to ban it," he says, "and the other is to provide incentives to people to invest more per child but in fewer children. So that can help reduce demand for polygamy and then help the economies to grow."
Gould says governments in poorer countries need to subsidize education. If there is a firmer link between a country's wealth and its human capital, governments will encourage men to devote themselves to finding a single, educated woman and fathering only a few children -- rather than having several wives and many children.