What Makes Someone Monogamous?

Wedding rings (BBC)

Wedding rings (BBC)

We can’t distill monogamy into a single magic formula. But some scientists have recently made strides in determining what factors might make a person monogamous.

One possible factor: genetics.

Researchers at Harvard University recently published a study examining the mating habits of deer mice and oldfield mice. In the wild, deer mice are promiscuous and oldfield mice are monogamous. Scientists first undertook an experiment to see how the two types of mice compare in parenting their young. Different parenting metrics were observed, such as building nests for the offspring.

After noting that the deer mice put in less parental efforts, the researchers wanted to see if the differences were down to genetics (ah, the old nature vs. nurture debate!). Five pairs of deer mice and oldfield mice were interbred, which produced 30 hybrid mice and later 769 (!) third-generation mice.

The parenting behaviors of these second- and third-generation hybrid mice ran the gamut from hardly involved to heavily-involved in their offsprings’ lives. In observing this, scientists were able to identify parts of DNA (termed loci) that determined parenting behaviors. The¬†experiment’s abstract in scientific journal Nature explained the findings:

Using quantitative genetics, we identify 12 genomic regions that affect parental care, 8 of which have sex-specific effects, suggesting that parental care can evolve independently in males and females. Furthermore, some regions affect parental care broadly, whereas others affect specific behaviours, such as nest building.

The abstract also notes that a certain gene expression is primarily responsible for the level of nest-building. No word on how that would translate to humans (the gene for interior decorating?), but it’s exciting to see some strides made in genetic research.

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