We’ve known it instinctively, now science confirms that watching a grandchild be happy and sad elicits strong reactions in the emotional part of the brain. But strangely, grandmothers watching their own children produced reactions in the more cognitive or thinking part of the brain.

The study by Emory University suggests grandmothers are geared toward feeling what their grandchildren are feeling when they interact with them. If their grandchild is smiling, they're feeling the child's joy. And if their grandchild is crying, they're feeling the child's pain and distress.

In contrast, the study found that when grandmothers view images of their adult child, they show stronger activation in an area of the brain associated with cognitive empathy. That indicates they may be trying to cognitively understand what their adult child is thinking or feeling and why, but not as much from the emotional side.

Professor of Anthropology, James Rilling, concluded that young children have likely evolved traits to be able to manipulate not just the maternal brain, but the grand-maternal brain.

Study co-author Minwoo Lee said he could personally relate to the research.

"I still remember warmly the moments I had with them. They were always so welcoming and happy to see me. As a child, I didn't really understand why."

It's relatively rare, Lee adds, for scientists to study the older human brain outside of the problems of dementia or other aging disorders.

We often assume that fathers are the most important caregivers next to mothers, but that's not always true. In some cases, grandmothers are the primary helper.

In fact, the "grandmother hypothesis" posits that the reason human females tend to live long past their reproductive years is because they provide evolutionary benefits to their offspring and grandchildren.

Evidence supporting this hypothesis includes a study of the traditional Hadza people of Tanzania, where foraging by grandmothers improves the nutritional status of their grandchildren. 

Another study of traditional communities showed that the presence of grandmothers decreases their daughters' interbirth intervals and increases the number of grandchildren.

And in more modern societies, evidence is accumulating that positively engaged grandmothers are associated with children having better outcomes on a range of measures, including academic, social, behavioural and physical health.

For the current study, the researchers wanted to understand the brains of healthy grandmothers and how that relates to the benefits they provide to their families.

The 50 participants in the study completed questionnaires about their experiences as grandmothers, providing details such as how much time they spend with their grandchildren, the activities they do together, and how much affection they feel for them.

They also underwent functional magnetic resonance imaging (fMRI) to measure their brain function as they viewed pictures of their grandchild, an unknown child, the same-sex parent of the grandchild, and an unknown adult.

The results showed that while viewing pictures of their grandchildren, most participants had more activity in brain areas involved with emotional empathy and movement, compared to when they were viewing the other images.

Grandmothers who more strongly activated areas involved with cognitive empathy when viewing pictures of their grandchild reported in the questionnaire that they desired greater involvement in caring for the grandchild.

"Our results add to the evidence that there does seem to be a global parenting caregiving system in the brain, and that grandmothers' responses to their grandchildren maps onto it," Rilling says.

Source: Medical Xpress