Why do people live so long? A new study suggests that a mother’s care could be an important part of that.
The Cornell University study says the reason humans and other primates live so long can be at least partially explained by the mother-infant relationship.
Maternal care leads to the evolution of “long, slow lives,” according to the study, which was published Friday in the peer-reviewed journal Proceedings of the National Academy of Sciences.
“Humans are primates and we live much longer than expected based on our body size, even compared to other primates. We also show very long periods of intense bonding between mother and child, which is unusual in animals,” says lead author Matthew Zipple told CBC News via email Wednesday.
“We argue in this study that these two facts are causally linked, such that the intensity of the mother-infant relationship partly explains our long lives, and those of other long-lived social mammals,” says Zipple, a postdoctoral researcher in neurobiology. conduct in the College of Arts and Sciences at Cornell University.
But because the authors link maternal care to human and animal lifespans, some researchers worry that the findings could be harmful to human mothers if taken out of context.
The study authors looked at demographic trends – at the species level – and did not draw parallels with modern parenting or suggest that mothers should spend more time with their children.
But the link between longevity and maternal care may create a temptation for some people to think that way, says Amanda Watson, a senior lecturer in sociology and anthropology at Simon Fraser University, who was not involved in the study.
At least one science news outlet has already cited the study as evidence that “a mother’s love is a powerful force, shaping not only our childhoods but possibly our entire lives.”
‘Maybe mothers still feel pressure and role tension when we read the text [study] head, and could this head be weaponized by some who wish to hinder the freedom of women? Of course, but they shouldn’t,” Watson said.
But no pressure
The researchers used modeling and empirical data to look at factors such as lifespan, maternal survival and offspring fitness in mammals. They made predictions based on Zipple’s research on baboons and other primates.
They were able to show that in species where the survival of the offspring depends more on the long-term presence of the mother, such as primates (including humans), they tend to live longer and reproduce less often.
And it’s not just about primates; the authors say the model also extends to other social mammals, such as elephants, hyenas and whales.
But it’s important to keep in mind what the authors mean when they say “maternal care” when interpreting the results, said Andrea O’Reilly, a professor at the School of Gender, Sexuality and Women’s Studies at the University of York, who was also not involved in the study.
Care in this case refers to the long, intense period of connection between mother and child that can influence the survival of the offspring to have children of their own.
Not the “hyper-vigilant, helicopter, sign your kids up for three programs at six months of age, kind of thing” that so many mothers already feel pressure to perform, said O’Reilly, who is known for establishing the academic discipline of motherhood studies and maternal theory.
“A lot of what we do in Western culture, at least over the last thirty to forty years, is classified as caring. Things moms should and should do. But I would suggest that a lot of that has nothing to do with caring for children. children It’s all about good mothering to mark you as a good mother,” O’Reilly told CBC News.
Her concern is that the research, if misinterpreted in this way, could be harmful to mothers who already face “impossible standards.” And she notes that it wouldn’t be the first time research has caused mothers to feel guilty, specifically pointing to attachment studies that say the first hour of a baby’s life is the most important for maternal bonding.
“So many mothers could not immediately bond with their child for various reasons (health or psychological) and they lived with so much shame and guilt. So I worry that in the wrong hands, this research is a way to regulate control and pushback among mothers. O’Reilly said.
“The last thing moms need is another study that says, ‘Oh my God, you need to do more for your child.'”
A postnatal retreat in Toronto offers new mothers 24-hour care, similar to popular services in China and South Korea. But a GP says the parents who need the help most are unlikely to stay in the luxury retreats.
No ‘right’ way to be a mother: Study author
It’s important to keep in mind that the correlations in the data do not examine the nature of the care relationship, Watson noted.
“We’re talking about the evolution of multiple species over millions of years, not about who should read the bedtime story,” says Watson.
Zipple, the author of the Cornell study, emphasized that his research is about evolutionary models, which help us better understand our place in biological history.
“We all have a mother. Our mother is our first social relationship, and for many people it remains one of the most influential social relationships in their lives,” he told CBC News.
“For better or for worse, we are animals too, with complex social behaviors and relationships deeply shaped by historical evolutionary forces.”
Evolution doesn’t distinguish between “good” behavior and “bad” behavior in the same way we do, he added.
“And so we should never assume that selective pressures from our evolutionary past can tell us about the ‘right’ way to be a mother or father or friend or husband or citizen.”
The mother and grandmother hypotheses
The Cornell study builds on so-called “mother and grandmother” hypotheses, which are also used to explain menopause and why women live longer than when they can produce more offspring.
Essentially, the theories state that it is beneficial for older females to stop reproducing because they achieve more evolutionary success by helping their children raise their grandchildren than by having more babies themselves, and the offspring are more likely to to survive when their mother and grandmother get into trouble. their lives.
Researchers have previously applied the theory to killer whales and four species of toothed whales, the only mammals other than humans known to experience menopause. They’ve even discovered that grandmother killer whales hang around to help mothers raise their calves.
(Not for nothing, but another recent study found that orca mother whales that raise male offspring are half as likely to breed successfully as mother whales that have female calves. The researchers suggested that this may be because the male offspring have a greater need need food and need more food.
In this study, the authors note that they have extended the logic of the mother and grandmother hypotheses “to a more general form that we expect will be relevant to mammalian taxonomy.”
Watson, of Simon Fraser University, says the mother and grandmother hypotheses should also be interpreted with “extreme caution.” She explains that scientists and anthropologists disagree about the significance of the correlations between the presence of grandchildren, advanced age and reproductive fitness.
Overall, studies like these provide “exciting clues” about highly social species, including humans, Watson said.
“But they are at best humorous when taken out of this context.”
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