“Laughter is the shortest distance between two people,” Victor Borge presumably once said.* As you have likely figured out by now, I enjoy discovering evidence that humans are not that different from other forms of life. We share many characteristics with the other living creatures with whom we share our planet. Today, I have one more example for you—laughter.

Laughing is an involuntary reaction in humans consisting of rhythmical contractions of the diaphragm and other parts of the respiratory system. External stimuli, like being tickled, mostly elicit it. We associate it primarily with joy, happiness, and relief, but fear, nervousness, and embarrassment may also cause it. Laughter depends on early learning and cultural factors (Davila-Ross & Palagi, 2022).

The study of humor and laughter is called gelotology (from the Greek gelos, γέλιο, meaning laughter).

Chimpanzees, gorillas, bonobos, and orangutans display laughter-like behavior when wrestling, playing, or tickling. Their laughter consists of alternating inhalations and exhalations that sound to us like breathing and panting (Crepaldi et al., 2024; Ross et al., 2010; Winkler et al., 2025)

Rats display extended, high-frequency, ultrasonic vocalizations during play and when tickled. We can only hear these chirping sounds with proper equipment. They are also ticklish, as are we. Particular areas of their body are more sensitive than others. There is an association between laughter and pleasant feelings. Social bonding occurs with the human tickler, and the rats can even become conditioned to seek the tickling (Panksepp & Burgdorf, 2000).

A dog’s laughter sounds similar to a regular pant. A sonograph analysis of this panting behavior shows that the variation of the bursts of frequencies is comparable with the laughing sound. Playing recorded dog laughter to dogs in a shelter can contribute to promoting play, social behavior, and decreasing stress levels (Simonet et al., 2005).

“Laughter is the shortest distance between two people.” Maybe it is simply the shortest distance between any two living creatures.

Keep laughing, my friends!

__________

* Victor Borge is widely credited with this quote, although there is no direct evidence linking it to a specific book, performance, or interview.

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References

Crepaldi, F., Rocque, F., Dezecache, G. et al. Orangutans and chimpanzees produce morphologically varied laugh faces in response to the age and sex of their social partners. Sci Rep 14, 26921 (2024). https://doi.org/10.1038/s41598-024-74089-x.

Davila-Ross, M. and Palagi, E. 2022. Laughter, play faces and mimicry in animals: evolution and social functions. Phil. Trans. R. Soc. B37720210177. http://doi.org/10.1098/rstb.2021.0177.

Panksepp, J., & Burgdorf, J. (2000). Laughing rats? Playful tickling arouses high-frequency ultrasonic chirping in young rodents. Consciousness and Cognition, 9(3), 551-572. https://files.eric.ed.gov/fulltext/EJ1069218.pdf.

Ross, MD, Owren, MJ, Zimmermann, E. The evolution of laughter in great apes and humans. Commun Integr Biol. 2010 Mar;3(2):191-4. doi: 10.4161/cib.3.2.10944. PMID: 20585520; PMCID: PMC2889984.

Simonet, P., Murphy, J., & Scaggs, M. (2005). Dog-laughter: Recorded playback reduces stress-related behaviors in shelter dogs. Animal Welfare, Purdue University Center for Animal Welfare Science. https://caninewelfare.centers.purdue.edu/resource/dog-laughter-recorded-playback-reduces-stress-related-aggression-in-shelter-dogs/.

Winkler, S.L., Laumer, I.B., Lyn, H. et al. Bonobos tend to behave optimistically after hearing laughter. Sci Rep 15, 20067 (2025). https://doi.org/10.1038/s41598-025-02594-8.