A Neuroscientist Gets To The Bottom Of The Nature vs. Nurture Debate
Before diving into it, let me tell you the take-home message: Both sides of the nature-nurture debate are right—a child's brain is both structured and plastic.
At birth, all children are equipped with a panoply of specialized circuits, shaped by genes, themselves selected by tens of millions of years of evolution. Babies' brains have a sense of the physics governing objects and their motion; a knack for spatial navigation; intuitions of numbers, probability, and mathematics; an inclination toward other human beings; and even a genius for languages—the blank-slate metaphor could not be more wrong.
And yet, evolution also left the door open to many learning opportunities. As I describe in my book, How We Learn, not everything is predetermined in the child's brain. Quite the contrary: The detail of neural circuits, on a scale of a few millimeters, is largely open to interactions with the outside world.
A case for nature:
The brains of young children swarm with possibilities and explore a much wider set of hypotheses than the brains of adults. Each baby is open to all languages, all scripts, all possible mathematics—within the genetic limits of our species, of course. That's where nature comes in.
The baby's brain comes equipped with an innate gift: powerful learning algorithms that allow them to adapt to the environment. Thanks to these innate abilities, as early as the first few days of life, the brain begins to specialize and settle into its configuration. The first regions to freeze are the sensory areas: Early visual areas mature in a few years, and it takes less than 12 months before the auditory areas converge toward the vowels and consonants of the child's native language.
A case for nurture:
This is not to say that intervention is not worth the effort, at any age: The brain retains some of its plasticity throughout its life, especially in its highest-level regions such as the prefrontal cortex. However, everything points to the effectiveness of early intervention.
Whether the goal is to teach an adopted child a second language or help a child adjust to deafness, blindness, or the loss of a whole cerebral hemisphere, the sooner, the better.
Our schools are institutions designed to make the most of the plasticity of the developing brain. Education relies heavily on the spectacular flexibility of the child's brain to recycle some of its circuits and reorient them toward new activities such as reading or mathematics. When schooling begins early, it can transform lives: Numerous experiments show that children from disadvantaged backgrounds who benefit from early educational interventions show improved outcomes, even decades later, in many domains—from lower crime rates to higher IQs and incomes to better health.
But schooling is not a magic pill. Parents and families also have a duty to stimulate children's brains and enrich their environments as much as possible. All babies are budding physicists who love to experiment with gravity and falling bodies—as long as they are allowed to tinker, build, fail, and start over again rather than being strapped in a car seat for hours. All children are nascent mathematicians who love counting, measuring, drawing lines and circles, assembling shapes—provided one gives them rulers, compasses, paper, and attractive math puzzles.
All infants are genial linguists: As early as 18 months of age, they easily acquire 10 to 20 words a day—but only if they are spoken to. Their families and friends must feed this appetite for knowledge and nourish them with well-formed sentences without hesitating to use a rich lexicon. Many studies show that a child's vocabulary at 3 to 4 years old directly depends on the amount of child-directed speech they received during their first years. Passive exposure does not suffice: Active one-to-one interactions are essential.
The bottom line.
All research findings are remarkably convergent: Enriching the environment of a young child helps her build a better brain (in other words, nurture wins). For instance, in children who are read bedtime stories every evening, the brain circuits for spoken language are stronger than in other toddlers—and the strengthened cortical pathways are precisely those that will later allow them to understand texts and formulate complex thoughts.
Likewise, children who are lucky enough to be born into bilingual families, with each parent giving them the wonderful gift of speaking in their native language, effortlessly acquire two lexicons, two grammars, and two cultures—at no cost.
Exposing the developing brain to a stimulating environment allows it to keep more synapses, larger dendrites, and more flexible and redundant circuits—like the owl that learned to wear prism glasses and kept, for its entire life, more diversified dendrites and a greater ability to switch from one behavior to another. Let's diversify our children's early learning portfolio: The blossoming of their brains depends in part on the richness of the stimulation they receive from their environment.
Adapted from How We Learn: Why Brains Learn Better Than Any Machine...for Now by Stanislas Dehaene, published by Viking, an imprint of Penguin Publishing Group, a division of Penguin Random House, LLC. Copyright © 2020 by Stanislas Dehaene.
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