Motherhood Confers Courage, Study Finds
November 3, 2003
When Hemingway described courage as "grace under pressure," he wasn't talking about motherhood. Researchers at the University of Richmond and Randolph-Macon College, however, have found that mother rats behave more courageously in stressful situations than females without progeny.
The researchers, whose earlier experiments showed that pregnant and nursing rats are smarter than their non-pregnant sisters, now have found mother rats also are calmer and braver under stress.
Neuroscientists Craig Kinsley of the University of Richmond and Kelly G. Lambert of Randolph-Macon College reported their findings in the current issue of Physiology and Behavior.
The researchers believe the results relate to any number of species, including human beings.
In one test, rats reacted to being held in a "restraint tube"--a clear Plexiglas tube--placed in a bright room.
"Rats don't like being restrained and they don't like light," Kinsley said. "This task makes them highly agitated."
The second test placed the rats into an open pen with walls. "Again," said Kinsley, "rodents like dark, covered areas; they don't like open and lighted spaces. They tend to hug the walls and move sparingly; they don't move around much because such movement may attract the attention of a variety of potential predators." The females with no pregnancy experience "moved only haltingly," according to Kinsley and Lambert. The rats with one or more pregnancies "spent more time exploring and, when we examined their brains, the regions that regulate fear showed less activation. Overall, they were much less fearful."
Kinsley believes hormonal changes during pregnancy and stimulation from offspring dramatically enrich the brain. He also believes the resulting changes are permanent.
"Females with offspring will go to great lengths to protect and care for their offspring, a significantly large and metabolically costly investment, and they'll be generally efficient and cool-headed in doing so," Kinsley said. "From the female's standpoint, if she's too frightened to fend off predators or other threats to her offspring, they will be lost to injury or death."