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18th February 2021
10:00am GMT
Since the 1960s, researchers have posited that one reason women tend to live decades past their reproductive years is that it increases the chances of their grandchildren surviving, through the physical support they often provide – a theory known as 'the grandmother hypothesis.'
And more recent evidence has suggested that children’s wellbeing and educational performance is also boosted by the presence of engaged grandparents.
To better understand the biological underpinnings of this connection, Prof James Rilling, an anthropologist at Emory University in Atlanta, Georgia, and colleagues recruited 50 women with at least one biological grandchild aged between three and 12, and used functional magnetic resonance imaging to scan their brains as they looked at photos of that child, the child’s parents, and images of an unrelated child and adult.
“What really jumps out is the activation in areas of the brain associated with emotional empathy,” Rilling said. “That suggests that 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.”
Rilling previously performed a similar exercise with fathers as they looked at pictures of their children. The activation seen in the grandmothers’ emotion processing areas, and in those associated with reward and motivation, was stronger, on average, than the fathers’ – although there were some dads who had just as much activation in these areas.
In contrast, when the grandmothers looked at images of their own adult child, slightly different brain areas tended to be activated: those associated with cognitive empathy. This could indicate that they were trying to cognitively understand their adult child, rather than experiencing this more direct emotional connection.
“Emotional empathy is when you’re able to feel what someone else is feeling, but cognitive empathy is when you understand at a cognitive level what someone else is feeling and why,” Rilling said.
This could possibly help to explain the experience many grown-up children have of their parents often seeming more excited to see their grandchildren than them. “I think that’s plausible,” said Rilling, whose findings were published in Proceedings of the Royal Society B.
“Young children have likely evolved traits to be able to manipulate not just the maternal brain, but the grand-maternal brain. An adult child doesn’t have the same cute factor, so they may not the same emotional response.”
The results support the idea that there may be a global caregiving system in the brain that is activated in mothers (who have been examined in separate studies), fathers and grandmothers. Rilling now hopes to study grandfathers and other childcare providers to see how they compare.
