Inching Toward the Sky

Habit and the Neuroscience of Becoming in "A Tree Grows in Brooklyn"

At the turn of the twentieth century, only one kind of tree grows in the tenement district of Williamsburg, Brooklyn.

“It had pointed leaves which grew along green switches which radiated from the bough and made a tree which looked like a lot of opened green umbrellas. Some people called it the Tree of Heaven. No matter where its seed fell, it made a tree which struggled to reach the sky. It grew in boarded-up lots and out of neglected rubbish heaps and it was the only tree that grew out of cement.”

Like the tree of heaven, young Francie Nolan will be asked to grow from this same concrete. She is the protagonist of Betty Smith’s A Tree Grows in Brooklyn, the child of a family that struggles to put food on the table. The sky feels out of reach for both plants and people in her neighborhood.

But one day in the library, Francie sees something that begins to change what she imagines for herself.

“She looked quickly at the little golden-brown pottery jug which stood at the end of the librarian’s desk…‘When I get big,’ she thought, ‘I’ll have a desk like this…and a clean green blotter…and a golden-brown bowl with a flower or some leaves or berries always in it and books...books...books.’”

Francie has seen a picture of who she might one day become. What she doesn’t yet know is that she is already being shaped into that person.

In Atomic Habits, James Clear describes personal growth as happening at three levels. The first is behavior; what we do. The second is outcomes; what we get. The third is identity; who we believe ourselves to be. The middle level is the one we typically measure. But the deepest change happens elsewhere.

Francie’s behavior, in the beginning, is established by the women in her family. They are frantic with worry about her future. What can they do to give her a chance? Francie’s grandmother delivers the kind of folk wisdom that anticipates what neuroscientists would later confirm in the laboratory—the power of habit.

“Every day you must read one page from some good book to your child. Every day this must be until the child learns to read. Then she must read every day, I know this is the secret.”

So before bed each night, Francie’s mother reads the children a page of the Bible and a page from Shakespeare. Some nights they are exhausted. They read anyway.

Inside the children, something invisible is beginning. Neuroscientist Ann Graybiel has spent decades tracing it in her laboratory. Her work centers on the basal ganglia, a set of deep, evolutionarily ancient structures that govern automatic behavior and the slow conversion of effort into habit. When she watches animals learning a repeated task, she sees the brain change. Early in learning, neurons in this area fire throughout the entire behavior, as though tracking each individual step. But with repetition, the activity migrates to only the beginning and end of the sequence. The brain is placing brackets around the routine, marking it as a single unit of action rather than a string of separate decisions.¹ Bracketed this way, the cost of starting drops. The cost of finishing drops. What once required effort begins to feel like instinct.

In the Nolan home, the Bible and Shakespeare open night after night. Years pass this way. Francie grows from infant to toddler to schoolgirl. She is being read to before sleep; she is learning the letters by day. Francie’s mother does not know what the outcome will be. The family still struggles to put food on the table. The tree of heaven still struggles to reach the sky. Then one ordinary day, something shifts.

“She looked at a page and the word ‘mouse’ had instantaneous meaning…The barrier between the individual sound of each letter and the whole meaning of the word was removed and the printed word meant a thing at one quick glance. She read a few pages rapidly and almost became ill with excitement…She could read!…On that day when she first knew she could read, she made a vow to read one book a day as long as she lived.”

This is the moment Francie’s brain has been preparing for. Effortful decoding has become instant recognition. The brackets sharpen, and the outcomes continue to follow. She becomes an A student. She graduates from grade school.

But Francie’s reading habit has done more than earn her a report card. The Bible and Shakespeare have given Francie rhythms older than her tenement, a vocabulary larger than Williamsburg. She has been carrying other worlds around inside her. One day, the world she actually lives in begins to look different against them.

“The scales at the tea store did not shine so brightly any more and she found the bins were chipped and shabby looking…the stores were all the same. Nothing was changing. She was the one who was changing.”

This is identity changing, the deepest of Clear’s three levels and the slowest to arrive. “Every action you take,” Clear writes, “is a vote for the type of person you wish to become.” Francie has been voting every night for years.

Once a routine has been grooved deeply enough, it becomes part of the brain’s automatic wiring. Control of the behavior migrates from regions that require effort to regions that no longer do.² The habit holds even when the rewards and structures that built it fall away. Thus Francie’s reading is no longer a daily act of will. It has become concrete her will can stand on rather than struggle through. Her brain has been quietly building something indomitable.

Eventually, the concrete is fully cured. Francie is accepted into college, and steps into the identity she once dreamed of. There will be a desk of her own now, freshly-sharpened pencils, a clean green blotter, and books—books, books, books. In her last days in Brooklyn, as she packs up to leave, she looks once more at the tree of heaven:

“The tree whose leaf umbrellas had curled around, under and over her fire escape had been cut down because the housewives complained that wash on the lines got entangled in its branches…But the tree hadn’t died...A new tree had grown from the stump and…grown along the ground until it reached a place where there were no wash lines above it. Then it had started to grow towards the sky again.”

Against all odds, one inch at a time, Francie has grown like this stubborn tree. And she has touched the sky.

Thank you Brigitte Kratz for your editing eye on this one!

1. In a 2018 study published in Current Biology, Graybiel’s lab trained rats to press two levers in varying specific sequences for a reward of chocolate milk. As the rats learned, the researchers recorded activity in the dorsolateral striatum, a region of the basal ganglia long associated with habit. Two patterns emerged in opposite directions. The excitatory projection neurons, which carry signals outward from the striatum to drive behavior, fired strongly at the first lever press and again at the last, but went quiet in the middle. The inhibitory interneurons, which dampen activity in surrounding cells, fired in the inverse pattern, active during the middle of the sequence and silent at the boundaries. Because each rat had learned a different sequence, the bracketing could not be explained by motor commands alone. It marked the routine itself as a unit. Martiros, Burgess, & Graybiel, “Inversely Active Striatal Projection Neurons and Interneurons Selectively Delimit Useful Behavioral Sequences,” Current Biology 28, no. 4 (2018): 560–573. https://pmc.ncbi.nlm.nih.gov/articles/PMC5820126/

2. In a 2008 review for the Annual Review of Neuroscience, Graybiel synthesized decades of research on how habits become physically encoded in the brain. Repetition gradually shifts a behavior’s control from the dorsomedial striatum, which supports flexible, goal-directed action, to the dorsolateral striatum, which supports habit. Once this transfer is complete, the behavior becomes remarkably resistant to change. In experimental paradigms where the original reward is removed or made aversive, animals continue performing the habitual behavior anyway. The neural signature has outlived the motivation that built it. Graybiel, “Habits, Rituals, and the Evaluative Brain,” Annual Review of Neuroscience 31 (2008): 359–387. https://web.math.princeton.edu/~sswang/basal-ganglia/graybiel08_annu_rev_neurosci_BG-evaluative-brain.pdf