More Singles Equals More Divorces, Research Suggests

Written by ryan. Posted in Uncategorized


Published on September 07, 2010 with No Comments

More singles equals more divorces, math research suggests

Human couples, like some birds that usually mate for life, may be more apt to break up when they live amongst a large number of single members of the population, according to a new mathematical model developed by a Valparaiso University professor.  Published in the Journal of Theoretical Biology this August, Daniel Maxin’s paper “A two-sex demographic model with single-dependent divorce rate” is the first to establish a model for how many divorces will take place as the number of single people rises or falls.

Maxin, an assistant professor of mathematics and computer science, said the idea behind his model is that the larger the number of single people in a city or town, the more alternative mates there are to tempt people who are in a relationship.  Conversely, the lack of such alternative mates may decrease the chance of couple separation. Where previous demographic models all assumed the divorce rate to be constant, his model makes the divorce rate dependent on the number of single people in that population.

Maxin said the idea for creating the new model came to him during graduate school when he visited a couple with two young children living in a remote area.  “I asked the parents whether their children fought a lot and the mother said ‘Yes they do, but they make up quickly because there is no one else to play with’,” Maxin said. “That led me to consider that with more singles around, there has to be a positive influence on the divorce rate. This influence is probably psychological in human populations, whereas for animals it is driven by instinct and it may provide an evolutionary advantage.”

Maxin said among animals this is known as the “better option hypothesis.” Among animals that form stable pairs, like the seabird known as the great skua, those pairs will separate more often if they have more options to find another mate.  One of his model’s main differences with previous models, Maxin said, is that it establishes a cycle in which the population stabilizes itself. While a large number of singles will drive the divorce rate up, the resulting lower number of couples will decrease the birth rate, which in turn lowers again the number of singles, easing the pressure on the divorce rate.  “This is much more realistic than other models in which a constant divorce rate would cause the population to increase exponentially, which doesn’t happen in reality,” he said.
Maxin is careful to point out that the number of singles versus couples is only one factor impacting the divorce rate. Population density and culture also play a critical role.  Maxin said that while the idea behind the paper is not easy to hear, it also serves as a reminder to couples that they should be diligent in maintaining a strong relationship.  “If people are aware that if there are a lot of options around that it’s easy to be lazy in relationship rather than working out whatever problems you might be having, then that could have a positive effect on reminding couples that they should work hard on their relationship at all times,” Maxin said.
Maxin’s research interests focus on population dynamics, and determining which factors are most important in driving whether a certain population grows or declines. Those factors can include, birth rates, death rates, food supply and, as his most recent paper suggests, the number of singles.
“Mathematically, the marriage dynamic is very interesting because there is no complete agreement about what function would best describe it,” Maxin said. In other words, there are many factors that plausibly could impact marriage rates and definitely proving which of those factors are the most important is challenging.”
He hopes additional studies are done exploring the efficacy of his mathematical model, which he plans to further develop.  Maxin says connecting his research and teaching is important.  “I’m planning to include this research in some of the mathematics classes I’m teaching and I save the last section of my classes for research topics so that students can see some of the very interesting real life applications of the math they’re learning,” Maxin said.
Maxin’s paper can be read online at

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