It turns out that children can understand complex scientific concepts—like natural selection—far beyond what most people would have expected.
To test this, cognitive developmental psychologist Deborah Kelemen and coresearchers created a 10-page picture storybook about pilosas, a group of fictional mammals with long trunks. Then they read it aloud to five- to eight-year-olds.
The pilosas, according to the story, use their trunks to catch insects. In the past, most of the pilosas had wide trunks. Only a few had thin trunks. Then extreme climate change drove most of the insects underground, into long, narrow tunnels where only the pilosas with thin trunks could reach them.
The drama unfolds around a central question: how did the pilosas evolve over time from a group of animals having trunks of varying widths to those with thin trunks predominating?
It’s a story about adaptation by natural selection, which is one of the core mechanisms not just of evolution, but of all biology. It is also one of the most widely misunderstood concepts in science. It is generally viewed as so complex—thus beyond the grasp of young children—that educational standards in the United States suggest that it should not be taught comprehensively until ages 13 to 18.
But the kids who heard the story about the pilosas got it.
“We’re still astonished by what we found,” says Kelemen, a Boston University College of Arts & Sciences professor of psychological and brain sciences. The findings of the team of three BU researchers and one from the University of Toronto were reported in a study published in 2014 in the journal Psychological Science.
“It shows that kids are a lot smarter than we ever give them credit for,” Keleman says. “They can handle a surprising degree of complexity when you frame things in a way that taps into the natural human drive for a good, cohesive explanation.”
“I had one child say to me, ‘Wow, I think my head is going to explode I learned so much today,’” says study coauthor Natalie Emmons, a BU developmental psychology postdoctoral fellow.
The conventional wisdom is that young children should be taught only piecemeal biological facts, such as that food is needed for survival or that animals have useful body parts, without tying the facts together into an explanation of how the mechanism of natural selection works.
Why bother trying to explain the mechanism to young kids? The researchers make the case that teaching it earlier may help head off learning problems later on.
Young children are natural explanation seekers, Kelemen writes in the study. Around preschool age, they intuitively start thinking that natural phenomena exist for a purpose or operate by design. To a five- to eight-year-old, it makes perfect sense that rivers exist so crocodiles have a place to live or that giraffes’ necks became long because they needed to reach leaves high in the trees.
This scientifically inaccurate thinking is known as teleological explanation. While it helps young children’s everyday reasoning, Kelemen says, the kind of beliefs associated with it can impede the ability of older students—and ultimately, adults—to understand the counterintuitive logic of natural selection. A species evolves over time as animals with certain traits that fit better with their environment survive and reproduce at higher rates than those without the advantageous trait.
Not only did the kids understand how the pilosas evolved in the storybook, but they accomplished one of the most difficult tasks of learning: generalizing the concept. They applied what they learned from the pilosas to another species of novel animals, in some cases even after three months.
Kelemen’s experiment, coming amid the growing discussion about the need to improve science literacy in the United States, began with this question: is it possible to teach young children a basic concept of adaptation by capitalizing on their efforts to figure out the natural world and the fragmentary state of their ideas?
Most storybooks that touch on natural selection only further confuse children, Kelemen says. They anthropomorphize the animals, skimp on the facts, and dispense with explanations altogether. Or the books are so flashy the kids can’t focus on the story. “All kinds of bells and whistles are often built into storybooks,” she says. “Everyone thinks that is going to make the storybook fun for the kid.”
Kelemen and her coresearchers crafted their book carefully, combining what they knew as developmental psychologists with the research on science education. They invented the pilosas so the children wouldn’t come into the lab with preconceived ideas about the animals. They kept the story and the pictures simple. The narrative about how the pilosas lived and died—and the explanation of how and why they evolved over time—unfolded gradually, with one biological fact logically connecting to the next.
The researchers asked the children questions before and after reading them the storybook to assess their learning of basic biological facts, such as the link between food and health and between health and reproduction, and their ability to integrate these facts into a coherent, accurate explanation of why pilosas’ bodies changed over time.
Learning was particularly striking among older students; in the second experiment, all of the seven- and eight-year-olds understood that the reason why the pilosas or other animals changed over time was because individuals with more beneficial traits outsurvived and outreproduced others in the group.
The study suggests that one way to improve science literacy in the United States is to start teaching earlier some key concepts that our natural tendencies of mind make especially hard to understand—and that a good place to start would be with natural selection. This concept, Kelemen says, is an important foundation for children’s understanding of other fundamentals, such as the diversity of living things and the origins of species.
“It turns out that if you put the facts into the context of a theory, the kids learn not only the facts, but they also understand the full explanation. And they get it beyond a level we ever imagined they would, given how young they are,” Kelemen says.
“We’re not necessarily getting rid of a natural orientation to think everything exists in nature to perform a function. What we are doing is helping children also develop alternative ways of understanding why some kinds of functions and purposes in nature exist. It is a scientifically accurate way that is going to help them in the science classroom and beyond.”
David Klahr, a Carnegie Mellon University professor of cognitive developmental psychology and education science, who was not involved with the study, says he is “impressed with the results,” and with the creativity of Kelemen and her team in conceiving and executing the work.
“We’ve known for years that young children can extract the intended message from a coherent story,” he says. “Everything from Aesop’s Fables to things in the typical ‘children’s bible stories’ volume exploits young children’s ability to extract meaning from well-crafted tales.”
“Taking insights from developmental research about how children think and applying them to the construction of educational materials can yield incredibly positive results,” says Kelemen. “Early interventions like this might be key to improving scientific understanding of counterintuitive ideas longer term.”