Fertility Influenced by Marriage Patterns

A group of British investigators from the University of Sheffield has recently determined that the patterns in which people marry are a very clear indicator of how the overall fertility patterns fluctuate. In other words, they believe, the way people marry can easily influence the fertility rates parents exhibit. The new study was conducted on a representative batch of women, whose records were pulled from old archives. In order to reduce the possibility for errors, the researchers turned to records from a time when divorce was forbidden.

The group collected the survival and marriage histories of 1,591 women, from Finnish church records dating back to the 18th and 19th centuries. Scientists at the University of Sheffield Department of Animal and Plant Sciences, led by experts Duncan Gillespie, Dr Virpi Lummaa and Dr Andrew Russell, then began peering through the records, in an attempt to find possible correlation between the ages at which people married and their fertility patterns. The differences between today's society and the one that existed 200 years ago are marked enough to guarantee the accuracy of the conclusions.

At that time, women tended to be married by the time they reached the age of 30 to 35 years. But those who married to wealthy men did so at an earlier age, which meant that they were very likely to turn into widows by the time they turned 40. They were generally wed to older men, who had sufficient money to attract the best partners. Society frowned upon older widows with children marrying again, which is certainly not the case today. Women get married later in life, and divorces are a lot more common then they were centuries ago.

This means that women today have a higher chance of reproducing at an older age than their counterparts din in the past. “Childbearing within a relationship is still the norm in modern society, but at ages where fewer women have the chance to reproduce, we should expect the evolution of lower fertility,” says Duncan Gillespie. “In today's society, family-building appears to be increasingly postponed to older ages, when relatively few women in our evolutionary past would have had the opportunity to reproduce. As a result, this could lead to future evolutionary improvements in old-age female fertility,” the expert concludes.