Abigail Tucker - Mom Genes: Inside The New Science of Our Ancient Maternal Instinct

Whether youre a mom, know a mom, or ever had a mom, you are going to want to read this surprising book. SY MONTGOMERY, New York Times bestselling author of The Soul of an Octopus

MOM GENES

Inside the New Science of Our Ancient Maternal Instinct

Abigail Tucker

NEW YORK TIMES BESTSELLING AUTHOR OF THE LION IN THE LIVING ROOM

The Lion in the Living Room

Gallery Books

An Imprint of Simon & Schuster, Inc.

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www.SimonandSchuster.com

Copyright 2021 by Abigail Tucker

All rights reserved, including the right to reproduce this book or portions thereof in any form whatsoever. For information, address Gallery Books Subsidiary Rights Department, 1230 Avenue of the Americas, New York, NY 10020.

First Gallery Books hardcover edition April 2021

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Jacket design by Jason Gabbert

Jacket photograph by Shutterstock

Author photograph by Ross Douthat

Library of Congress Cataloging-in-Publication Data

Names: Tucker, Abigail, author.

Title: Mom genes : inside the new science of our ancient maternal instinct / Abigail Tucker.

Description: First Gallery Books hardcover edition. | New York : Gallery Books, 2021.

Identifiers: LCCN 2020045858 (print) | LCCN 2020045859 (ebook) | ISBN 9781501192852 (hardcover) | ISBN 9781501192869 (ebook)

Subjects: LCSH: Motherhood. | MothersPsychology.

Classification: LCC HQ759 .T928 2021 (print) | LCC HQ759 (ebook) | DDC 306.874/3dc23

LC record available at https://lccn.loc.gov/2020045858

LC ebook record available at https://lccn.loc.gov/2020045859

ISBN 978-1-5011-9285-2

ISBN 978-1-5011-9286-9 (ebook)

For Ross

Then all went on their knees, and holding out their arms cried, O Wendy lady, be our mother.

Ought I? Wendy said, all shining. Of course its frightfully fascinating, but you see Im only a little girl. I have no real experience.

That doesnt matter, said Peter though he was really the one who knew the least. What we need is just a nice motherly person.

Oh dear! Wendy said. You see, I feel that is exactly what I am.

J. M. Barrie, Peter Pan (1911)

I T FEELS like I grew a new heart.

Thats what my best friend told me the day her daughter was born. Back then, I rolled my eyes at her new-mom corniness. But ten years and three kids of my own later, Emilys words drift back to me as I ride a crammed elevator up to a laboratory in New York Citys Mount Sinai Hospital, where cardiologists are probing the secrets of maternal hearts.

Every year, thousands of pregnant women and just-delivered mothers land in emergency rooms with a life-threatening type of heart failure. Symptoms include swollen neck veins and shortness of breath. Their hearts can hardly pump. The cause of this peripartum cardiomyopathy is unknown, but its the kind of health disaster that for regular people ends in a prompt heart transplant, or oblivion.

Yet fate has a different design for the fledgling moms. About 50 percent spontaneously get better, exhibiting the highest rate of recovery for this type of illness. Some mom hearts are practically as good as new in as little as two weeks. Adult heart tissue doesnt rally easily, but new mothers may somehow be able to regrow heart cells the way salamanders sprout new tails.

At this Mount Sinai Hospital lab, a cardiologist named Hina Chaudhry thinks shes figured out why. After surgically injuring mother mice to simulate a heart attack, and then cutting out and dissecting their tiny tickers, she and her research team discovered just what they expected: heart cells with DNA that doesnt match the mothers own.

The mystery cells belong to unborn mice. During pregnancy the baby mouses cells cross the placenta into the mothers body, joyriding around in her blood vessels until cardiac damage happens, at which point they sense inflammation and make a beeline for her wounded heart. Its a little like how my second daughter sprints at me with a Band-Aid when I scrape myself grating Parmesan for dinner.

They just zoom in, says Chaudhry. These cells home to the heart like heat-seeking missiles.

Multiplying in maternal chests, the fetal stem cells transform into blood vessellike tubes and even something that looks an awful lot like the holy grail of cardiology: full-fledged heart muscle cells, which cardiologists have struggled for decades to re-create in a lab. The mothers crippled organ likely uses this fresh tissue to heal.

It feels like I grew a new heart.

On a nearby computer screen, Chaudhry pulls up highly magnified video footage of these fugitive baby mouse cells in a petri dish. Tagged with a green fluorescent protein, they look like fresh peas in a dish of gray gravy.

She hits play, and the peas begin to pulse, to twitch. Ga-gung, ga-gung, they seem to say, like Patrick Swayze in Dirty Dancing. I squint. Why on earth, I ask, are the fetal cells bopping around like that?

Chaudhry grins. Theyre beating.

Its not just hearts. A mothers body is like her living room, strewn with kid castoffs and debris. Scientists discover fetal cells in the darnedest places, like when I find somebodys shin guards stuffed behind the TV, or a tiara in the laundry basket. Our children colonize our lungs, spleens, kidneys, thyroids, skin. Their cells embed in our bone marrow and breasts.

Often they stay forever. Scientists find rogue fetal cells while dissecting the cadavers of old ladies, whose littlest babies are now middle-aged men. Long after giving birth, the bodies of surrogate mothers are scattered with the genes of strangers progeny.

The phenomenon is called fetal microchimerismmicro, because these are typically teeny numbers of cells, only a handful per millimeter of blood in pregnant women, and fewer in moms later in life.

A chimera is a type of awkward Greek monster remixed from various familiar creatures, until an entirely new organism arises.

On my computer screen I stare at statues of these ancient freaks cast in bronze: goat legs, lion heart, dragon wings and fire breath billowing out of one of three heads.

Thats no monster, I think. Thats me most mornings. Thats a mom.

Although fetal microchimerism is evolutionarily ancient and common in mammalian moms from cats to cows, modern researchers are just getting around to studying it. So it goes for much of the science surrounding the two billion or so human moms patrolling the planet today. Though in a sense, there are far more of us than that, since microchimerism also flows the other way, with mothers stray cells trespassing into babies bodies and living on through them. Thus, while one of my dearest friends died of cancer three years ago, a fraction of her cells are currently attending second grade.