The roots of laughter can be traced back to our common ancestors with other great apes, living around 10 to 15 million years ago.

• Provine, R. R. (2000). Laughter: A Scientific Investigation. New York: Viking Press.
  • This book by Robert R. Provine, a pioneering researcher on laughter, discusses the evolutionary roots of laughter and its development in early hominins. Provine suggests that laughter has deep evolutionary roots tied to social bonding and play behaviors, with its origins possibly tracing back to the early stages of human evolution around 2 to 4 million years ago.
• Gervais, M., & Wilson, D. S. (2005). The evolution and functions of laughter and humor: A synthetic approach. The Quarterly Review of Biology, 80(4), 395-430.
  • Gervais and Wilson explore the evolutionary origins of laughter, suggesting that it likely evolved during a critical period of hominin social evolution. They propose that laughter became a crucial social tool for early hominins, with its emergence potentially occurring around 2 to 3 million years ago, as hominins developed more complex social structures.
• Dunbar, R. I. M. (2012). The Social Brain Hypothesis and its implications for social evolution. Annals of Human Biology, 39(5), 375-392.
  • Robin Dunbar, a well-known evolutionary psychologist, discusses how laughter and other social behaviors evolved as part of the broader social brain hypothesis. Dunbar suggests that laughter played a significant role in maintaining social bonds in early hominins, particularly during the period when hominins were developing larger social groups, roughly 2 to 4 million years ago.
• Panksepp, J. (2007). Neuroevolutionary sources of laughter and social joy: Modeling primal human laughter in laboratory rats. Behavioural Brain Research, 182(2), 231-244.
  • While focusing on the neuroevolutionary aspects of laughter, Panksepp’s research discusses the evolutionary trajectory of laughter-like vocalizations, indicating that the roots of human laughter can be traced back to early hominins, around 3 million years ago. This time frame aligns with the development of more sophisticated social and emotional behaviors.
• Vettin, J., & Todt, D. (2004). Laughter in conversation: Features of occurrence and acoustic structure. Journal of Nonverbal Behavior, 28(2), 93-115.
  • This study examines the acoustic structure of human laughter and its conversational functions, noting that the evolution of laughter likely coincided with the development of complex social communication in early hominins. The authors suggest that these developments may have occurred around 2 to 4 million years ago.