A gene variant for one of the receptors for the hormone vasopressin in voles, is also associated with how human males bond with their partners, according to a new study by an international research team.
The scientists discovered that the "334" allele of a common gene variant AVPR1A, the human version of avpr1a studied in voles, may have negative effects on men''s relationship with their spouses.
"Our findings are particularly interesting because they show that men who are in a relatively stable relationship of five years of more who have one or two copies of allele 334 appear to be less bonded to their partners than men with other forms of this gene," said Jenae Neiderhiser, professor of psychology, Penn State.
She added: "We also found that the female partners of men with one or two copies of allele 334 reported less affection, consensus and cohesion in the marriage, but interestingly, did not report lower levels of marital satisfaction than women whose male partners had no copies of allele 334."
Scientists have extensively studied the comparable gene in voles, a mouse-like animal, and have linked this gene to vole bonding behaviours since a long time.
But, this study was the first to suggest that the knowledge on vole pair-bonding may also apply to humans and may help to inform research on human disorders related to impaired social interactions and communication, such as autism.
Recently, some research on AVPR1A in humans has suggested a possible link with autism and certain social behaviours, such as altruism, but no direct link to human pair-bonding had previously been known.
"A study by Erica Spotts, National Institute on Aging, using this sample was one of the first to show genetic influences on marital relationships, but did not reveal which genes were involved. The work on pair bonding in voles was very exciting because it suggested to us a specific gene to examine," said Neiderhiser.
For the study, the scientists interviewed 2,186 adults taking part in the Twin and Offspring Study in Sweden (TOSS). The TOSS study collected detailed information from pairs of twins and their partners or spouses about their marital relationships, personality and mental health, as well as genetic data.
They found that in men, having allele 334 was inversely linked to measures of the strength of a person''s bond to their mate.
They also report that men who carried two copies of allele 334 were more than twice as likely to report serious marital or relationship problems, such as facing threat of divorce, as men who had did not carry it. These men also were almost twice as likely to be unmarried as men with no copies, despite having a long-term relationship with their mate.
The study also revealed that women married to men with one or two copies of allele 334 scored lower on measures of marital quality than women married to men not carrying this allele.
"In this new paper, Hasse Walum did an excellent job of linking this work to the work with voles by constructing the partner bonding measure that was then examined for associations with polymorphism in the gene AVPR1A," said Neiderhiser.
The study complements findings from similar animal research and suggests that the well-defined relationship between genes, the brain and pair-bonding behavior in voles may also be relevant for humans.
The study is reported in the latest on-line issue of the Proceedings of the National Academy of Sciences.