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.

Read the full Evolutionary Mismatch series:

  1. Introduction: Evolutionary Mismatch and What To Do About It by David Sloan Wilson
  2. Functional Frivolity: The Evolution and Development of the Human Brain Through Play by Aaron Blaisdell
  3. A Mother’s Mismatch: Why Cancer Has Deep Evolutionary Roots by Amy M. Boddy
  4. It’s Time To See the Light (Another Example of Evolutionary Mismatch) by Dan Pardi
  5. Generating Testable Hypotheses of Evolutionary Mismatch by Sudhindra Rao
  6. (Mis-) Communication in Medicine: A Preventive Way for Doctors to Preserve Effective Communication in Technologically-Evolved Healthcare Environments by Brent C. Pottenger
  7. The Darwinian Causes of Mental Illness by Eirik Garnas
  8. Is Cancer a Disease of Civilization? by Athena Aktipis
  9. The Potential Evolutionary Mismatches of Germicidal Ambient Lighting by Marcel Harmon
  10. Do We Sleep Better Than Our Ancestors? How Natural Selection and Modern Life Have Shaped Human Sleep by Charles Nunn and David Samson
  11. The Future of the Ancestral Health Movement by Hamilton M. Stapell
  12. Humans: Smart Enough to Create Processed Foods, Daft Enough to Eat Them by Ian Spreadbury
  13. Mismatch Between Our Biologically Evolved Educative Instincts and Culturally Evolved Schools by Peter Gray
  14. How to Eliminate Going to the Dentist by John Sorrentino
  15. Public Health and Evolutionary Mismatch: The Tragedy of Unnecessary Suffering and Death by George Diggs
  16. Is Shame a Bug or a Feature? An Applied Evolutionary Approach by Nando Pelusi
  17. The “Benefits,” Risks, and Costs of Routine Infant Circumcision by Stephanie Welch
  18. An Evolutionary Perspective on the Real Problem with Increased Screen Time by Glenn Geher
  19. Did Paleolithic People Suffer From Kidney Disease? by Lynda Frassetto
  20. The Physical Activity Mismatch: Can Evolutionary Perspectives Inform Exercise Recommendations? by James Steele


  1. Blaisdell, A. P. (2015). Play as the foundation of human intelligence: The illuminating role of human brain evolution and development and implications for education and child development. Journal of Evolution and Health, 1(1), Article 9. http://dx.doi.org/10.15310/2334-3591.1016.
  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.
  6. Geschwind, D. H., & Konopka, G. (2012). Genes and human brain evolution. Nature, 486, 481-482. http://www.nature.com/nature/journal/v486/n7404/full/nature11380.html.
  7. Liu, X., Somel, M., Tang, L., Yan, Z., Jian, X., Guo, S., et al. (2012). Extension of cortical synaptic development distinguishes humans from chimpanzees and macaques. Genome Research, 22, 611-622. http://genome.cshlp.org/content/early/2012/01/30/gr.127324.111.
  8. Petanjek, Z., Judas, M., Simic, G., Rasin, M. R., Uylings, H. B. M., Rakic, P., & Kostovic, I. (2011). Extraordinary neoteny of synaptic spines in the human prefrontal cortex. PNAS, 108, 13281-13286. http://www.pnas.org/content/108/32/13281.full.
  9. Somel, M., Franz, H., Yan, Z., Lorenc, A., Guo, S., Giber, T., Kelso, J., Nickel, B., Dannemann, M., Bahn, S., Webstere, M. J., Weickert, C. S., Lachmann, M., Paabo, S., & Khaitovich, P. (2009). Transcriptional neoteny in the human brain. PNAS, 106, 5743-5748. http://www.pnas.org/content/early/2009/03/20/0900544106.
  10. Garlick, D. (2010). Intelligence and the brain: Solving the mystery of why people differ in IQ and how a child can be a genius. Self-published.
  11. Thompson, J. L., & Nelson, A. J. (2011). Middle childhood and modern human origins. Human Nature, 22, 249-280. http://link.springer.com/article/10.1007/s12110-011-9119-3.
  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.

Published On: February 22, 2019

Aaron Blaisdell

Aaron Blaisdell

Dr. Aaron Blaisdell is a UCLA Psychology Professor where he runs the Comparative Cognition Lab. Dr. Blaisdell is a member of the UCLA Brain Research Institute, the UCLA Integrative Center for Learning & Memory, and the UCLA Evolutionary Medicine program. He received a BA in Anthropology (SUNY Stony Brook), an MS in Anthropology (Kent State University), a Ph.D. in Behavioral Neuroscience (SUNY Binghamton), and had 2 years of NIH-funded postdoctoral training (Tufts University). Dr. Blaisdell studies animal cognition, behavioral neuroscience, and ancestral health. He co-founded the Ancestral Health Society and is Editor-in-Chief of the Journal of Evolution and Health.


  • M. Makuye says:

    Perseveration in play can be driven in great part by sociality, but not at all exclusively. In fact, perseveration may exclude social partners in play, to varying extents.
    Play, observed, appears to be the evolved (rewarded by “expectation-of-reward” internal self-signaling molecules) method of learning, in neuron-containing species.
    Play can involve large sensorimotor response, small-muscle development (as in the case of music, vocalization, and fine arts), cognitive modeling of futuure events and responses.
    The reward mechanisms differ, and insight into impulses -whether overtly reported by narrative cognitive structure, or by probably in-part lateralized “feelings” and impulses (arguably not exclusively generated or even reported through cortical activity) may show that we cycle through feelings of reward in response to species-dependent capacities.
    Anabolic molecules appear to function as important cognitive generators of feelings of reward, which might be better termed “expectations of reward.” Reward is achieved in satiation, when the impulse for immediate perseveration is temporarily ended. Many organisms, may be visibly playing when, for example, carnivorae and odontoceti appear to play when capturing prey.
    I’ve observed Canis lupus using play stimuli when attempting to evoke prey responses useful for evaluation.

    In our social omnivore, we observe play that isolates and culls individuals and other groups from what would normally seem affiliative. Play, then, fades and segues into practicality, although practicality may be alienating, antisocial, or having territorial or ultimately, reproductive outcomes.
    Play, also, it appears, transforms into every activity not normally described as facultative. Only some of the signaling rewards may persist when social play is not the goal, but you will notice that some less-than-social actions retain a high proportion of cognitions of rewarding play.

    Recent assessments of some gene expression involved in perseveration in domestic canids share identity with highly similar genes in autistic and other dysfunctionally or relatively asocial humans. Stress relief, another factor, , seems to occur differentially, not only in the dimension of relieving somatic, proprioceptive signals, but in balancing sociality and the exercise of a cognitive need such as Kahneman’s Type 2 thinking.

    Yo have some work cut out for you; circadian, seasonal and other neurohormonal cycling and pheromonal signaling not researched, factor into impulses and feelings of play. We’re not even Copernican on the issue yet.

  • Gordon Burghardt says:

    I find that this article discussing play from an evolutionary standpoint seems to almost completely ignore the comparative literature on play, animal neuroscience studies of play, theories and models of play and play evolution, and empirical studies of play and play functions. The latter were mostly based on hand waving in the past, but now some solid studies are being done. Any reader of this article would do well to consult the Pellegrini edited Oxford Handbook of the Development of Play (2011) and the newly released Cambridge Handbook of Play: Developmental and Disciplinary Perspectives. (P. K. Smith & J. L. Roopnarine, eds., 2018, Cambridge University Press) for a more complete and diverse perspective on this important topic. Most, if not all the ideas here were proposed earlier, including the boldface key idea. This is, of course, a popularized essay, but readers should have been pointed to more key literature. I have recently compiled an Oxford Bibliographies in Psychology literature source on play (http://www.oxfordbibliographies.com/view/document/obo-9780199828340/obo-9780199828340-0222.xml?rskey=CyyJUT&result=1&q=play#firstMatch) that can also serve as an entrance to both historical and current important references on play.

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