What used to be a biological imperative is now a point of contention. Mothers staying close to their babies, nurturing and nourishing them in their early years, was how our species survived and thrived for millennia.

Now, an author and psychoanalyst who dares to suggest that mothers should be their child’s primary caregiver, at least for the first three years of life, is under fire for fueling the “mommy wars.” Erica Komisar’s book, Being There: Why Prioritizing Motherhood in the First Three Years Matters, details the scientific evidence that mothers are the best early caregivers of their children and that substitutes—daycares, nannies, relatives, even dads—are not comparable to the care that only mothers can provide.

Komisar’s book is scathing in its honesty. She says there is no such thing as a good daycare. She says that the guilt many working mothers feel over not staying home with their children is good. “Guilt is a signal feeling,” she says. It’s a sign that should not be ignored but listened to. She writes in her book: “Too often, mothers are putting their work and their own needs ahead of their children’s.”

Needless to say her ideas are not well received by many. The Wall Street Journal reported on the book last week, writing about Komisar’s recent publicity experiences:

“Christian radio stations ‘interviewed me and loved me,’ she says. She went on ‘Fox & Friends,’ and ‘the host was like, your book is the best thing since the invention of the refrigerator.’ But ‘I couldn’t get on NPR,’ and ‘I was rejected wholesale—particularly in New York—by the liberal press.’ She did appear on ABC’s ‘Good Morning America,’ but seconds before the camera went live, she says, the interviewer told her: ‘I don’t believe in the premise of your book at all. I don’t like your book.’”

Komisar, a New Yorker who considers herself to be politically liberal, discovered in her private clinical practice what she felt was an unmistakable link between rising rates of childhood mental health issues and absent mothers. She told the Journal:

 “What I was seeing was an increase in children being diagnosed with ADHD and an increase in aggression in children, particularly in little boys, and an increase in depression in little girls.” She realized that “the absence of mothers in children’s lives on a daily basis was what I saw to be one of the triggers for these mental disorders.”

So as not to be a hypocrite, Komisar, 53, waited to write her book until her children were older and didn’t rely as much on her emotional and physical closeness. She writes in her book: “The truth is, we can do everything in life, but not at the same time.”

While Komisar advocates for a more “child-centric society” that can appeal to liberals and conservatives alike, her left-leaning political views support policies such as a year-long paid maternity leave for new mothers. By arguing that mothers matter—and that they matter more than we may think—Komisar hopes to make the case for government policies that prioritize motherhood.

Conservatives, who are often embracing of stay-at-home-motherhood but eschew coercive state policies, gravitate strongly toward Komisar’s child-centric ideas. On the other hand, according to The Wall Street Journal article, “most liberals won’t even acknowledge the problem.”

The data presented in Komisar’s book are compelling and hard to ignore. She finds that “infants and toddlers who have the constant and consistent presence of an attentive and sensitive mother are more likely to be emotionally and psychologically healthy children and adolescents.”

A mother as a child’s primary caregiver in the early years is incomparable and non-substitutable. Mothers provide the nurturing, emotional connection, and security that babies need in order to grow into happy, healthy, well-adjusted children and adults. The problem is obvious and the science is clear: mothers matter.