Toddler on smartphone
Aug 19, 2022

Kids' Puzzle-Solving & What May Make Humans Unique Among Species

New findings from a TWCF-funded study show that cognitive flexibility supports the development of cumulative cultural learning in children.

By Templeton Staff

New research funded in part by a TWCF grant sheds light on the phenomenon of cumulative cultural evolution. The paper, published in Nature's Scientific Reports, examines the role cognitive flexibility plays in the development of cumulative cultural learning. The findings, based on results from a series of puzzle-based experiments designed for young children, indicate that the process of cumulative cultural evolution is "contingent on the capacity to flexibly switch to, and maintain, improved behaviors."

What is Cumulative Cultural Evolution?

Human technological advancement continuously unfolds at an ever-increasing pace and scope, resulting in dramatic transformations in how we communicate, learn, work, play, and live. Think of the strides made in the last century alone — we've graduated from simple computers housed in huge rooms to devices that are pocket-sized yet many times more powerful; from steam-powered cars to today's self-driving vehicles. By iteratively building and improving upon each other's discoveries and behaviors, humans create vast systems of knowledge that are transmitted both within and between generations. This process is known as cumulative cultural evolution.


Why do chimpanzees, our closest primate relatives, have roughly the same technological repertoire they’ve had for thousands of years, and human children use iPhones?


Cristine Legare, founding director of the Center for Applied Cognitive Science and a co-author of the paper, spoke previously with Stories of Impact about why researchers are curious about the workings of cumulative culture. "Ultimately, we want to try to understand why it is that our closest primate relative, the chimpanzee, has roughly the same technological repertoire that they’ve had for thousands of years, and human children are using iPhones. We want to understand the kind of cognitive infrastructure that underlies cultural complexity, as well as innovation, differences between the species, and how that develops over time." The study detailed in the paper was set up to investigate the strengths and limitations of the cognitive abilities underlying behavioral flexibility in both species.

The Study

The study took place with a group of 167 U.S. children, aged 3-5 years old, participating in a series of experiments at the Thinkery Children's Science Museum in Austin, Texas. The aim was to learn if and when the children would switch from an inefficient puzzle solution to a more efficient one. The puzzle given to the children involved retrieving a token from a Serialbox, a transparent polycarbonate box with 4 compartments, hinged lids, and finger holes. This was the same multi-solution puzzlebox given to chimpanzees in a separate study led by a co-author of the paper, Sarah Davis, facilitating comparisons between the two species' responses.


Although other animals do maintain group behaviors that are conveyed socially, the complexity and diversity of cumulative culture in humans is often cited as what makes us unique among species. 


Although other animals do maintain group behaviors that are conveyed socially, the complexity and diversity of cumulative culture in humans is often cited as what makes us unique among species. Cognitive flexibility — the ability to adapt to a constantly changing environment — may help explain this difference. "Behavioral inflexibility has been proposed as a potential explanation for relative cultural stasis in nonhuman animals," says the research team. In particular, this inflexibility and related "behavioral conservatism" has been noted in chimpanzees. "Experimental studies with chimpanzees have shown they are unlikely to adopt more effective or efficient solutions to puzzles having already learned less effective or efficient ones. Such species-specific constraints on behavioral flexibility may explain the relative dearth in cultural complexity and greater frequency of behavioral conservatism in other species."

Behavioral conservatism occurs when prior knowledge prevents or delays adoption of an alternative behavior. This behavior has also been documented in human children. "Children appear more flexible in the absence of prior knowledge or explicit rules," say the researchers, referencing for example an earlier study, in which children who witnessed a demonstration before interacting with a puzzlebox generated fewer novel solutions than children who did not see the demo. This behavior was also observed in the team's most recent work.

"Overall most (67%) children did switch to the efficient method. But, almost all children (85%) who did switch also reverted back to their original inefficient method at least once," reports a co-author, Bruce Rawlings, sharing the findings via Twitter. "In a contrast condition, where children learned the efficient method first, most children (97%!) switched to the inefficient method after observing it demonstrated." Children were keen to explore an alternative solution but, like chimpanzees, were overall conservative in reverting to their first‑learned one.


In contrast to chimpanzees, young children can readily relinquish inefficient task solutions to switch to more efficient ones.



In contrast to chimpanzees, the paper's findings conclude that:

  • Young children can readily relinquish inefficient task solutions to switch to more efficient ones.
  • Children also show a strong proclivity to return to initially learned solutions. This suggests a robust tendency to rely on initially learned solutions from adults — even if they are less efficient.
  • In showing that children quicker to switch solutions were also those that were more likely to maintain them over multiple task interactions, the findings also provide new insights into which individuals are key to the uptake and preservation of improved cultural traits.

Find the full paper in Nature's Scientific Reports by Sarah Davis, Bruce Rawlings, Jennifer M. Clegg, Daniel Ikejimba, Rachel E. Watson‑Jones, Andrew Whiten, and Cristine H. Legare.