Science

Study reveals most babies conceived when father 6 yrs older than mother

by William Atkins

Saturday, 01 September 2007

Austrian study performed in Sweden shows that a couple whose husband is 5.92 years older than his wife will produce the most children.

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Austrian anthropologist Martin Fieder, Department of Anthropology, University of Vienna (Austria), and Austrian researcher Susanne Huber, Institute of Wildlife Ecology, University of Veterinary Medicine (Vienna, Austria), analyzed the extensive and detailed birth and populations records of ten thousand people throughout Sweden.

The people considered for the study had given birth to one or more children and had kept the same partner while conceiving all of the children. Of these records, the statistics of 6,000 women and 5,600 men born between the years 1945 and 1955 were selected.

The article describing their results shows up in the Tuesday, August 28, 2007 online version of the Royal Society's journal Biology Letters. In the abstract to their paper, the researchers stated: “Preferences for certain age characteristics of partners are reported across cultures: men prefer mates who are younger and women prefer mates older than themselves.... [W]e find maximum offspring count in men if their partner is approximately 6 years younger, and in women if their partner is approximately 4 years older. We further find that after separation, on average, both men and women shift to a partner younger than the first, albeit in women the new partner is still older than the female herself. We conclude that the age preference for the partner yields fitness benefits for both men and women and may thus be an evolutionarily acquired trait.”

Specifically, the results showed that men who were 5.92 years younger than the mother of their children, whether they are married or not, had, on average, 2.2 children, the larget number of children of any pair of people with respect to their difference in ages. In addition, women who were 3.97 years younger than the father of their children had, on average, 2.1 children.

The difference between these age differences and the number of children, according to the researchers was due to the fact that the people were randomly selected so were not necessarily married to another person in the survey.

The researchers state, “These findings may account for the phenomenon that whereas men typically prefer and mate with women younger than themselves, women usually desire and mate with men older than them, We conclude that the age preference for the partner increases individual fitness of both men and women, and may thus be an evolutionarily acquired trait.”

In addition, according to Times Online, “The global average is for men to prefer a partner who is 2.66 years younger than them, and for women to prefer a partner who is 3.42 years older.”

Fieder contends that men have preferred younger women over the ages because such women have more child-bearing years ahead of them than older women. He also conjectures that women may prefer older men because such men are wealthier than younger men because they have had more years to accumulate money and, consequently, are able to better support them and their children.

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