USA Today
Grateful children have long recognized the healing power of a mother's love.
Scientists have even measured its biological effects, charting the chemical reactions set in motion by a hug or kiss. When mothers soothe their children, levels of hormones involved with love and trust surge, and stress hormones plummet. Now, for the first time, a study shows that just a mother's voice can set off the same chemical cascade.
The findings could shed light not only on the way that the brain works but also on the way language and relationships evolved, says Seth Pollak of the
University of Wisconsin-Madison and co-author of the study, published today in the
Proceedings of the Royal Society B: Biological Sciences.
"It's the kind of thing that should make parents relax a little bit, " Pollak says. "There are lots of different ways that you can provide support and comfort and care for a child."
Pollak conducted an experiment with 61 girls, ages 7 to 12, in which he measured their hormone levels before, during and after a stressful assignment: speaking and solving math problems before an audience. As predicted, levels of the stress hormone cortisol soared. Researchers also measured the hormone oxytocin, which helps mothers bond with their infants. Oxytocin levels spiked sharply in girls who saw their mothers after the exercise, confirming that a hug or pat on the back have measurable biological effects.
Surprisingly, however, oxytocin levels rose just as much in girls who spoke to their moms on the phone, Pollak says. That suggests that the human brain is wired to respond not just to sight and touch, but even to sounds, says Lane Strathearn of Baylor College of Medicine/Texas Children's Hospital Houston, who wasn't involved in the new study.
"This is incredible stuff," Strathearn says.
