Functional Frivolity: The Evolution and Development of the Human Brain Through Play

No matter where in the world you go, which culture you visit, or when in history you may have lived, there is one unwavering human universal. Children play. In modern western society there are iconic paradigms of play, such as ball games, jumping rope, skipping, rock-paper-scissors, video games, army men and space aliens, cowboys and Indians (or cops and robbers), dolls and dollhouses, a box full of crayons, kites, cars, trains, and planes. The list goes on. Other playful pastimes have existed time immemorial, such as skipping stones on water, foot races and games of chase, strength competitions, rough and tumble play, building toy houses of sticks and stones or castles and moats in the sand, hide and seek, dancing, rhymes and singing, jokes and tickling, and of course imaginary play.

Wherever you see a human universal, you can be sure there’s an important functional reason for it. What could be the functional role of such a frivolous activity as play? Perhaps play is not frivolous, but instead is an adaptation designed to guide proper cognitive development in human children. My line of reasoning is based on three strands of empirical evidence.¹

The first line of evidence is from human brain evolution. Since the origin of genus Homo, brains have tripled in volume. There have been major events of heterochrony, that is, changes in the timing of development.^{2, 3} For instance, the human brain is not fully mature until the early 20s, whereas the brain of the chimpanzee, our closest living relative, reaches maturity in about 10 years. Also, some human unique genetic changes have resulted in a dramatic increase in the density of dendritic spines and changes in the timing of brain development.^4-9 These changes resulted in a massive increase in both information processing capacity and in the potential for abstract representation through a protracted synaptic pruning process.¹⁰

The protracted pre-adult development, with elongated and new stages of childhood,¹¹ increased the developmental time over which experience can shape the brain and its cognitive capacities.¹² This human-unique intellect includes long-term planning, higher levels of abstraction than shown by any other animal, such as analogical reasoning, language for symbolic representation of thought, tool use for mastery over our environment, and a cumulative culture.

Second, unlike nonhuman animals, imaginary play is a central process of human cognitive development.¹³ Humans enter the world equipped with capacities for rational thought and causal understanding.^{14, 15} We also show a natural ability to reason scientifically (i.e., through controlled experiments) when we tinker with a new toy or try to figure out why something works the way it does or doesn’t work at all.¹⁶ We seek answers to puzzles and violations of our expectations in a sophisticated way and following principles of folk physics.¹⁷

Finally, the way children in hunter-gatherer bands and other ancestral-like societies develop their intellectual capacity is through play and exploration.^{18, 19} While the knowledge base, complexity, and scientific understanding of the world have changed dramatically since the dawn of agriculture, and even more so since the industrial revolution, our brains are still the same as in our Pleistocene ancestors. Thus, any wholesale change in the educational context of child development could have significant negative impacts through the introduction of evolutionary mismatches.

How could such an evolutionary mismatch arise? In modern society, we attempt a top-down approach towards guiding human intellectual development through academic training. This has created an evolutionary mismatch where the way the brain’s intellectual capacity is naturally shaped—through play, has been replaced to a large degree with directed instruction and academic skills training.²⁰

A problem with the approach taken by modern education is that it can result in decanalization of normal brain developmental processes.^{1, 21} As a result, many of the important intellectual capacities such as logical thinking, curiosity, analytic thought, and mathematical understanding might not fully develop or they develop incorrectly.^{22, 23} Furthermore, the mismatched rearing environment and resulting impaired brain development could be significant contributors to the huge increase in developmental psychopathologies, such as Attention Deficit Disorder, as well as mood disorders such as major depression (MDD) and clinical anxieties.¹⁸

We would do well to think about how human brains and intellect naturally develop and to take steps to bring our educational system in alignment with the needs of our growing brains. Clues as to what the optimal educational environment is comes from anthropology, child cognitive development, and neuroscience. It is time we face these facts and change our educational system.

References:

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2. Neubauer & Hublin (2010). The evolution of human brain development. Evolutionary Biology. DOI 10.1007/s11692-011-9156-1. http://link.springer.com/content/pdf/10.1007%2Fs11692-011-9156-1.pdf.

3. Shea, B. T., (1989). Heterochrony in human evolution: The case for neoteny reconsidered. Yearbook of Physical Anthropology, 32, 69-101.

4. Charrier, C., Joshi, K., Coutinho-Budd, J., Kim, J-E., Lambert, N., Marchena, J. D. et al. (2012). Inhibition of SRGAP2 function by its human-specific paralogs induces neoteny during spine maturation. Cell, 149, 923-935. http://www.cell.com/abstract/S0092-8674%2812%2900462-X.

5. Dennis, M. Y., Nuttle, X., Sudmant, P. H., Antonacci, F., Graves, T. A., Nefedov, M., et al. (2012). Evolution of human-specific neural SRGAP2 genes by incomplete segmental duplication. Cell, 149, 912-922.

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12. Sim, Z. L., & Xu, F. (2014). Acquiring inductive constraints from self-generated evidence. Cognitive Science. https://mindmodeling.org/cogsci2014/papers/251/paper251.pdf.

13. Buchsbaum, D., Bridgers, S., Weisberg, D. S., & Gopnik, A. (2012). The power of possibility. Phil Trans R. Soc B. 367, 2202-2212. http://rstb.royalsocietypublishing.org/content/367/1599/2202.short.

14. Walker, C. M., & Gopnick, A. (2014). Toddlers infer higher-order relational principles in causal learning. Psychological Science, 25, 161-169. http://pss.sagepub.com/content/early/2013/11/22/0956797613502983.

15. Xu. F., & Kushnir, T. (2013). Infants are rational constructivist learners. Current Directions in Psychological Science, 22, 28-32. http://cdp.sagepub.com/content/22/1/28.abstract.

16. Decker, J. H., Lourenco, F. S., Doll, B. B., & Hartley, C. A. (2015). Experiential reward learning outweighs instruction prior to adulthood. Cognitive and Affective Behavioral Neuroscience, 15, 310-320. http://www.ncbi.nlm.nih.gov/pubmed/25582607.

17. Povinelli, D. J., & Dunphy-Lelii, S. (2001). Do chimpanzees seek explanations? Preliminary comparative investigations. Canadian Journal of Experimental Psychology, 55(2), 185-193.

18. Gray, P. (2013). Free to learn: Why unleashing the instinct to play will make our children happier, more self-reliant, and better students for life. Basic Books.

19. Konner, M. (2010). The evolution of childhood: Relationships, emotion, mind. Harvard University Press.

20. Katz, L. G. (2015). Lively minds: Distinction between academic and intellectual goals for young children. https://deyproject.files.wordpress.com/2015/04/dey-lively-minds-4-8-15.pdf.

21. McGrath, J. J., Hannan, A. J., & Gibson, G. (2011). Decanalization, brain development and risk of schizophrenia. Translational Psychiatry, 1, e14. http://www.ncbi.nlm.nih.gov/pubmed/22832430.

22. Kamii, C. (2013). Physical-knowledge activities: Play before the differentiation of knowledge into subjects. In L. E. Cohen & S. Waite-Stupiansky, (Eds.), Learning Across the Early Childhood Curriculum (Advances in Early Education and Day Care, Volume 17), Emerald Group Publishing Limited, pp. 57-72. http://www.emeraldinsight.com/doi/abs/10.1108/S0270-4021%282013%290000017007.

23. Kamii, C., & Dominick, A. (1997). To teach or not to teach algorithms. Journal of Mathematical Behavior, 16, 51-61. http://www.sciencedirect.com/science/article/pii/S0732312397900079.