The Thread®

'Mom Genes' aims to examine biological transformations of motherhood

Mom Genes: Inside the New Science of Our Ancient Maternal Instinct, by Abigail Tucker
Mom Genes: Inside the New Science of Our Ancient Maternal Instinct, by Abigail Tucker
Gallery Books

The theme of transformation is central to Abigail Tucker's “Mom Genes.”

When women give birth and become mothers, writes Tucker, who is a science writer and mother of four, they "rebuilt from the ground up" as they undergo a "radical self-revision" that involves "a monomaniacal focus" on the baby.

Hormone and brain-based changes drive this transformation and "make a mother," she writes. New moms derive intense pleasure from their infant, experience heightened sensitivity to cues and signals coming from the baby, and are overtaken with a need to help and protect the baby at all costs.

Tucker's argument is not a subtle one: Full stop "babies occupy a special place in the hearts of all men and women, and in our neural circuitry as well."

I wonder: Has Tucker met anyone whose heart just isn't into babies? I have; they're just as human as anyone else. And sometimes, sadly, real pathology occurs, as Tucker acknowledges by reporting that the most likely killer of a week-old American baby is that infant's mother.

Infant emotions affect mothers more profoundly than anyone else, Tucker says. In one study, the prefrontal cortex of moms became active in a different region compared to women who had never been pregnant as they viewed pictures of angry, scared, or happy babies. Moms' brains may be structurally different too, she notes. One lab found "stark differences and gray matter reductions in the brains of twenty-five first-time moms versus the brains of twenty childless women," Tucker cites. The alterations were seen when comparing the moms' brains to their very own pre-pregnant brains, as well, changes as extensive as those seen in survivors of traumatic brain injuries.

But Tucker's descriptions of how radically women may change at the time of motherhood — and, as an extention, how this might affect their ability to focus on other things — gets pretty harrowing.

In the book, she states that moms are people who are "enthralled, in every sense of the word" with their babies, who desire to "do anything at all for your child, at every given moment." Because of this compulsion, it's necessary for moms to "acknowledge our lack of agency," she writes.

In this suite of transformations lurks trouble for anyone planning to work, or even focus clearly, as a new mother. Tucker notes: "If we are wholly intent on the texture of our child's bowel movements, we can't quite put our finger on the quadratic equation."

"This idea of being hijacked, hacked, overridden, reprogrammed, or otherwise assigned a new identity is the stuff of dystopian female fiction, from ‘The Stepford Wives’ to ‘The Handmaid's Tale,’” Tucker writes. Yet she embraces that view in the guise of humor, referring to her new-mom sibling as the "organism formerly known as my little sister."

My main complaint here is that brain scans and laboratory tests don't map well onto real-world maternal behavior. In that real world, U.S. Sen. Tammy Duckworth gave birth while governing in office. Prime Minister of New Zealand Jacinda Ardern led a country as a new mom. Scientists, artists, and business leaders routinely perform their jobs as new moms. But it's not just famous women who are the point here; many of us moms have managed to work well and to parent well simultaneously, even when work-place and cultural support is unfortunately minimal.

A view of new mothers as brain-compromised and incompetent isn't a cute meme, it's damaging to women who may have to fight a tide of suspicion about their competence. Maternal wall bias, as it's called, refers to discrimination against working mothers, including new mothers. "Maternal wall bias can manifest in different ways, coming from hiring committees, colleagues, and individuals conducting performance evaluations," reports Science magazine.

Now back to the science. If hormones prime maternal behaviors and brain changes, what does this mean for adoptive moms? "The evidence we have suggests that choosing to care deeply for a baby can awaken and physically mold the maternal brain," Tucker writes. Of course, adoptive parents already know that parenthood isn't necessarily dependent on biology at all.

Tucker is wedded to the word "instinct" but she does qualify it quite a bit. Instinct is both fixed and flexible, she asserts. Human moms do not somehow magically know what they are doing, because experience makes a large difference, as do various environmental and cultural factors, she writes. And depressed mothers are likely to be less aroused by infant signals, and this muted interaction may in turn damage babies' health at the level of the DNA. "Thus the babies under-stimulate their already-depressed mothers, tightening the spiral," as Tucker writes.

(For readers sensitive to animal cruelty, this book is tough going in places: "Disable a mother rat's nose, and she can still see her babies. Blind her eyes, and she will smell them." Many more examples ensue.)

Occasionally Tucker breaks out of the heteronormative man-woman-baby structure of the book, as when she reports research on gay dads. In two-father households, the physiology, including the brains, of the dads "more closely resembled maternal patterns than did the brains of heterosexual fathers," she writes. Here, responsiveness to infant stimuli is recognized as primary.

Tucker's grasp of the environmental stressors experienced by poor women is welcome: "Almost all the risk factors for maternal struggle are heightened for impoverished moms." She writes movingly of class privilege, including in her own life. Her call for government support for new moms, often harried by sleeplessness and at the mercy of capricious work schedules, makes good use of national comparatives. (Here I learned the Dutch word kraamverzorgster, a type of baby nurse made available to new moms in the Netherlands, for up to eight hours daily in the first two weeks after birth. In New Zealand, another type of baby nurse tracks new moms for five years.)

But by the time the stronger chapters occur, the damage has been done by the earlier wild claims of new moms falling apart. It doesn't help that Tucker refers to "differences between mothers and regular women" and uses "mom genes" language despite reporting scientists' cautions that genetic contributions to maternal variation are subtle, affecting the quality of maternal behavior in nuanced ways.

Tucker's deep dive into the scientific literature on new motherhood and her visits to labs unlocking mysteries of motherhood enliven her writing. Unfortunately, she renders the experience of new motherhood as such a draconian, impairing biological transformation that these positive aspects can't offer balance.

Barbara J. King is a biological anthropologist emerita at William & Mary. Her seventh book, Animals' Best Friends: Putting Compassion to Work for Animals in Captivity and in the Wild, was published in March. Find her on Twitter @bjkingape

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