The idea that new babies are empty vessels waiting to be filled with knowledge of the world around them doesn’t sound unreasonable. With their unfocused eyes and wrinkly skin, tiny humans sometimes look more like amoebas than complex beings.

Yet scientists have built a body of evidence, particularly over the last three decades, that suggests this is patently untrue. “When kids are born, they’re already little scientists exploring the world,” said the filmmaker Estela Renner via a video conference from Brazil before a recent screening of her new documentary The Beginning of Life (streaming on Netflix) at the World Bank in Washington, D.C.

That’s something Renner, a Brazilian mother of three, discovered as she spoke with early-childhood experts and parents in nine countries around the world about the impact a child’s environment in the first few years of life has on not only her physical development, but her cognitive, social, and emotional development, too. “I didn’t know that kids were not blank slates,” she said. “It changed the way I look at babies.” If more people recognized that fact, the way communities and policymakers think about and invest in the early years of life might be different.

Exquisitely shot and hopeful-without-being-sugary, the film focuses on the day-to-day lives of babies and parents and on the opportunities for learning in even the most mundane activities. “Babies are the best learning machines in the universe,” Alison Gopnik, a psychology professor who has spent decades studying child development, said in the documentary. “They’re the world’s original inventors,” echoed Patricia Kuhl, the co-director of the University of Washington Institute for Learning and Brain Sciences.

As an adult, just watching a baby who is on the verge of crawling is exhausting. Again and again, he’ll try to rock and wiggle his way forward, tapping into a seemingly endless supply of determination. Give a toddler a spoon and she’ll drop it from her high chair over and over, testing to make sure it clatters each time and watching for her mom to pick it up and hand it back. “There’s this inborn drive for mastery,” said Jack Shonkoff, the director of the Center on the Developing Child at Harvard University. These moments are crucial for development, and parents and the other children and adults who make up a child’s world have an enormous role in creating an environment where children have both the freedom and support to learn.

Consider a father preparing breakfast for his toddler. It’d be easy, faster, certainly, to strap the baby into a high chair and tune out the babble for a few minutes. But give the kid an empty bowl and a spoon and he’ll create a whole imaginary meal alongside his dad, offering sample “tastes.” Ask what kind of sauce he’s making and maybe, like one tyke in the film, he’ll offer up “mango” as a reply.

Children with high self-esteem who feel loved and supported are willing to try new things and to fail a lot in the process, said Andrew Meltzoff, Kuhl’s co-director at the Institute for Learning and Brain Sciences, because they know they’ll be safe. Even preschoolers who shout “no” at tired parents are testing the supportive boundaries of their environments. Where people often suggest that toddlers, given their frenetic tendencies, have trouble paying attention, in reality, they have trouble not paying attention. Everything piques their senses, from the sight of a passing car, to the soft fur of a dog, to the sizzle bacon makes when it hits a hot pan. They need help processing, but also the physical and mental space to take it all in.

Like all people, if babies feel rooted in a community, if they feel a sense of belonging, they are more willing to explore and take risks that help them learn precisely because they know they have someplace and someone who serves as an anchor. The support they feel or don’t feel in the early years influences what they expect from the world around them in the years to come.

The first few years of brain development might be equated to the construction of the frame of a house, said Charles Nelson, who has studied how early experiences impact brain and behavioral development. Just as a house can’t stand without a sturdy frame, a child is unlikely to thrive without a supportive environment in the early years. Kids who spend their babyood in loving and enriching environments are more likely to stay in school and become productive adults. They are likely to be healthier. But when babies don’t have adults who engage with them, pathways in the brain that form a child’s “frame” can disintegrate. Similarly, when babies see bad behavior, say their parents fighting, they are more likely to think that behavior is the appropriate way to resolve a conflict because it’s what they know.

Helping children thrive doesn’t mean providing the best toys or the most expensive gadgets, though. Quite the opposite; learning happens when children create their own play worlds. A child who sees a ruler and a pen and turns them into an airplane is often using more of her imagination and stimulating more of her brain than a child who is handed an already-put-together toy. “Play is the major vehicle for children to learn,” Shonkoff said.

While the film is not explicitly political and is intended for a wide audience, it does point out that children thrive when they have parents who have time and resources to devote to their upbringing. Right now, the United States is one of the only countries that does not offer paid maternity leave and few fathers are able to take paternity leave, meaning many babies often spend just a few waking hours with their parents. A 2013 Pew Research Center report found that in dual-income households, mothers spend about 12 hours per week on childcare, where fathers spend only about seven. And while no one in the film is criticizing working parents, the documentary does point out that parents who are able to cultivate strong relationships with their children are ultimately helping shape more productive adults. “That love is an important part of the economy,” said the economist James Heckman.

But it’s not always viewed that way, with employers frequently expecting parents to return to the working world quickly and to work inflexible schedules that make parenting well difficult. Although the film does make note of this, its focus is primarily on parents and families, not on specific policies that might help people be good parents. While “children are not raised by government, they’re raised by people,” Shonkoff said, he also pointed out that governments need to support people who are raising children. And people raising children need to care about the future of more than just their own child. The future of society quite literally depends on it.