Article of the year award 2020: Intelligence and fertility correlate

Nordic Mensa Fund granted four “Article of the year awards” in 2020.

The articles rewarded range from demographics to psychiatry, from psychology to education. They show the wide range of intelligence research. We now want to tell you a little more about each of the four recipients, in random order. This is number 1 out of 4.

Martin Kolk was awarded for his article: Cognitive ability and fertility among Swedish men born 1951–1967: evidence from military conscription registers published in the journal Proceedings of the Royal Society B.

The study from the area of demography focused on the paradox of human behavior in industrialized societies assuming that high socioeconomic status is usually negatively associated with reproductive success. This study analysed fertility histories and military conscription tests of Swedish men born in 1951-1967 and unlike many other studies, it showed a positive relationship between intelligence and fertility. 

The main finding was that men with the lowest categories of IQ scores had the fewest children, and that relationship was most pronounced for the transition to a first child. Higher IQ individuals were shown to have the first children at an older age, but that did not affect on the total number of children. While the study was restricted to men, it clearly shows that intelligence is also an important predictor for fertility, hence supporting that having an average to high intelligence favors fertility and sexual selection.

Martin Kolk is a Swedish researcher and Docent in Demography at the Stockholm University Demography Unit. He is also working at the Institute for Future Studies in Stockholm, and the Center for Cultural Evolution at Stockholm University. His research is mainly focused on how demographic processes are shaped by kinship and family networks over multiple generations, using contemporary and historical Swedish administrative register data. He is also working on determinants of fertility in the Nordic countries, including aspects such as cognitive ability, income, health and education.