Is your mom warmer with her grandkids than you? Blame biology, study says

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(CNN) — You know that special bond your mother seems to have with your kids? The one she doesn’t seem to have with anyone else, even you?

You’re not just imagining it, according to a new study.

Unlike other primates, humans rely on one another to help raise their children, and often those offspring do better when they have other adults, like their grandmothers, involved in their lives, said lead study author James Rilling, a professor of anthropology and professor of psychiatry and behavioral sciences at Emory University in Atlanta. The importance of grandmothers can be traced neurologically, this study suggests.

Researchers found that grandmothers shown images of their biological grandchildren had a neurological response in the areas of their brain that are important for emotional empathy and motivation.

The study, published by the journal Proceedings of the Royal Society B, worked with 50 grandmothers who reported having positive relationships with their grandchildren and high levels of involvement with them.

The women underwent functional magnetic resonance imaging (fMRI), which measures changes in blood flow that happen with brain activity, while being shown images of their grandchild, another child they didn’t know, an adult they didn’t know, and the same-sex parent of their grandchild. For some that was their own biological child, and for others it was their daughter- or son-in-law.

“This work points to the fact that there are important brain changes in members of a ‘village’ that raise a child. It’s not just the brain of birthing parents and partners that change,” said Jodi Pawluski, a neuroscientist and therapist based in France who was not associated with the study. “That is exciting.”

More emotional response for grandkids

Studies have examined maternal and paternal brain functions in the past, but this is one of our first glimpses into how a grandmother’s brain reacts to their grandchildren, Rilling said.

“The study was partially motivated by the well-known ‘grandmother hypothesis,’ which posits that human female post-menopausal longevity evolved because of the benefits grandmothers were able to bestow on their grandchildren,” Rilling said via email.

The novelty of the study and the nature of it being early days in brain-scan findings mean that the results are preliminary, said anthropologist and primatologist Sarah B. Hrdy, professor emerita of anthropology at the University of California, Davis, who was not associated with the study.

Some findings aren’t surprising: Grandmothers showed more of a response when looking at their grandchildren than children they didn’t know, according to the study.

Interestingly, grandmothers showed brain activity correlated with cognitive empathy more when looking at their biological children and in-laws than their grandchildren. When looking at their grandchildren, they showed stronger emotional empathy than they did with their children.

“Emotional empathy is feeling the emotions that another person is feeling. Cognitive empathy is understanding what someone is thinking or feeling and why,” Rilling said.

That could mean that while grandparents were wired to seek to understand their adult children’s feelings, they are more geared to an emotional response when it comes to grandchildren.

“Not only is it showing that the brain of grandmothers is activated with grandparenting, it also shows that the parental brain areas are activated late in life, or perhaps are always activated. Once a mother, always a mother,” Pawluski said. “This supports and expands what others have recently reported in that there are continued effects of parenting on the brain into aging.”