A woman gets on a bus with her baby. The bus driver says: "That's the ugliest baby that I've ever seen. Ugh!" The woman goes to the rear of the bus and sits down, fuming. She says to a man next to her: "The driver just insulted me!" The man says: "You go right up there and tell him off—go ahead, I'll hold your monkey for you."

This is officially selected as the funniest joke in the United Kingdom and it will stimulate much spontaneous laughter. (1)

But why do humans laugh? That question increasingly interests scientists around the globe. People of all ages and cultures laugh spontaneously, and they spend quite a bit of time doing it. Laughter is a feature that we share with other great apes such as the chimpanzee and gorilla, which suggests that it is an ancient behavior. (2)

So this leads us to suggest that we are dealing here with a biological adaptation, a trait that gave humans some sort of evolutionary benefit. What could that be? There are different hypotheses. One is that laughter signals social interest, especially in a romantic context. Not surprising, scientists find that a sense of humor is one of the most desired traits in a partner. Interestingly, there is a sex difference here. While women like men who make them laugh, men prefer to interact with women who laugh about the jokes they tell them. It is this deeper sexual motive that might drive men, and perhaps the not-so-appealing-looking ones, to become stand-up comedians.

Yet there are other reasons too why we laugh. For instance, laughter induces positive affect in people which will facilitate their capacity to learn new things. That’s why laughter and play go hand in hand. Especially in children playful activities are an excellent way to learn new skills. And what laughter does is to signal that they are in a safe environment where they can play and learn.

The third reason why humans laugh is to connect socially with each other in groups. Groups are important for human survival and across evolutionary time, groups got larger and socially more complex which raises the interesting question how these groups could be held together. Other primates groom each other to smoothen social interactions but this is impossible when groups get really large. One solution to this problem is laughter. Through laughing we can quickly establish a good relationship with each other, and because it is so contagious it can quickly spread through an crowd. (3)

So far, however, scientists could not come up with a plausible biological mechanism how laughter could produce these positive social effects. We think we found this. It’s endorphins.

In a series of experiments, conducted with a team of researchers from the Universities of Oxford and VU Amsterdam, led by Robin Dunbar, we invited participants to come to the lab. They first took a pain test. We put a frozen wine cooler sleeve on their arm – with a maximum duration of 3 minutes. Then we split the sample in half and one group watched a comedy video clip on the TV such as America’s funniest home videos, whereas the other group watched a neutral factual documentary (e.g., how to play golf). Then each individual took the pain test again. After watching the neutral clip people’s pain tolerance went down, as expected. Yet, after watching the comedy pain tolerance went up by as much as 50% in some of our studies. (4)

How do we know this was because of laughter? Well, first we measured laughter in all conditions. And the more people laughed the better they were enduring the pain. Was it not just positive affect induced by watching the comedy? We controlled for that in a separate experiment whereby we also showed a romantic video to a third group. They reported to feel happier but their pain tolerance did not go up. Does this also work outside the lab? We replicated the study’s findings during the famous Edinburgh Fringe Festival. We tested people who either watched or participated in a comedy show or a drama. Again, pain tolerance only increased after watching or participating in the comedy. How do we know it’s endorphins? Unfortunately, there is no easy way to directly measure endorphin levels other than through sticking a needle in people’s spinal cord. Yet, there is some recent evidence from research with brain scans suggesting that laughter does release endorphin levels in the brain.

So we find evidence that laughter is indeed a good medicine. We are currently examining whether this applies to clinical populations too and whether there are beneficial effects of using clowns in hospitals. (There is some research on patients showing that exposure to humor and comedy does reduce their medication; yet it is not clear yet whether laughter is responsible for this). And, separately we are studying the effects of laughter on trust and commitment on team performance in the workplace.

So far our findings suggest that laughter works in the same way as a good massage or an intense jog. It is equally relaxing but much more social. And the side effects—the occassional bad joke—are less severe than traditional medicine. 


Twitter: @ProfMarkvugt

1. http://en.wikipedia.org/wiki/World's_funniest_joke

2. Davila Ross, M,., Owren, M. J., & Zimmermann, E. (2009). Reconstructing the evolution of laugher in great apes and humans. Current Biology, 19, 1-6.

3. Van Vugt, M., & Kameda, T. (2012). Evolution and groups. In J. Levine, Group Processes. Psychology Press.

4. Dunbar, R, Baron, R., Frangou, A., Pearce, E., Van Leeuwen, E., Stow, J., Partridge, G., Macdonald, I., Barra, V., & Van Vugt, M (2012). Social laughter is correlated with an elevated pain threshold. Proceedings of the Royal Society-B, 279, 1161-1167. doi: 10.1098/rspb.2011.1373

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