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A new study of the prairie vole, a rodent species famed for its monogamous ways, has shown that the vole’s brain chemistry changes when its mate is taken away, and that it loses some of its vim and vigor. Researchers compared the behavior of males who were separated from either their mates or their siblings, and found that those voles who had lost their loyal mates were passive and unresponsive–maybe even depressed.

Prairie voles are one of the few mammals that are generally monogamous; the mates form life-long bonds and rear their pups together. In the new study, researchers subjected all the male voles to stress tests, like dunking them in basins of water and holding them suspended by their tails, and found that the voles whose mates had been spirited away put up less struggle. In the water, for example, they floated listlessly instead of paddling for their lives. These voles “basically were passive — they gave up,” [study coauthor Larry] Young said. “I would be hesitant to say that these animals were depressed, but their behavior is reminiscent of what you would see in a depressed person” [HealthDay News].

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Researchers have found a gene in men that’s linked to happy marriages, according to a new study. The gene determines how the brain responds to a hormone that has previously been shown to cause monogamous behavior in prairie voles; researchers found that men with a certain variant of the gene were less likely to be married to their partners, and if they were married, they were more likely to have had a marital crisis and to have discussed the possibility of divorce.

In the study, researchers studied the genetics of more than 550 men who were in relationships, and then asked both the men and their partners a series of questions. Men with a variant of the gene tended to score badly on a questionnaire designed to assess how well they bond with their partner and were more likely to report having suffered marital difficulties…. The wives of those who were married were also less satisfied with their marriage than women whose husbands did not have that genetic variant [Telegraph].

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A new study has shown that people with symmetrical bodies are judged more attractive by members of the opposite sex, even though the degree of symmetry may be impossible to discern by the naked eye. But researchers say the test subjects were mostly responding to more obvious body characteristics that have been shown to be linked to symmetry; namely broad shoulders and tall stature in men, and small torsos and an “hourglass” shape in women.

Researchers hypothesize that a symmetrical body may indicate a healthy person with an evolutionary advantage. “In animals with two sides that were designed by natural selection to be symmetrical, subtle departures from symmetry may reflect poor development or exposure to environmental or genetic stress,” said study team member William Brown of Brunel University in the U.K. “In many species these departures are related to poor health, lower survival, and fewer offspring” [National Geographic News].

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