The Science and Evolution of Laughter

Isn’t it curious that when something strikes us as funny, we might end up showing our teeth, altering our breathing, feeling weak in certain areas, or even crying? What’s behind this peculiar response known as laughter? When you laugh, your abdominal muscles contract rapidly, which disrupts your breathing patterns. This increases the pressure in your chest cavity and forces air out, sometimes producing snorts or wheezes. The intense use of these muscles can also lead to soreness, and laughter can impair your reflexes and muscle control, making your legs feel weak.

So, where does this odd behavior come from? Without archaeological evidence, pinpointing the exact origins of laughter is challenging, but scientists have proposed some theories. Interestingly, humans are not the only animals that exhibit laughter-like behavior. In the late 1990s, researchers discovered that rats made sounds similar to giggles when tickled. Evidence now suggests that at least 65 species, including some birds and primarily mammals, vocalize during social play. This includes our close relatives, the primates. By analyzing the sounds primates make while playing, scientists believe that laughter-like behavior may date back to our ancient ancestors.

It’s thought that laughter may have originally evolved as a way to signal friendly, non-aggressive intent during play. However, humans laugh not only during playful moments but also when we are amused, surprised, confused, or nervous. Some scientists propose that laughter’s role expanded after humans evolved larger social groups and more complex language. They suggest that laughter became a tool to convey emotions and subtle meanings in conversation, making it contagious. Hearing laughter can trigger laughter in others, activating brain regions linked to emotional responses.

In studies, people tend to laugh longer and more often in the presence of others, even if their amusement level is the same as when alone. Human laughter is generally louder than the play vocalizations of many animals, possibly because it serves not only as a personal signal but also as a broadcast to everyone around. Observers can distinguish between close friends and acquaintances just from brief clips of their laughter. Additionally, we can often tell whether a laugh is genuine or fake based on its sound. Fake laughter, or volitional laughter, uses different brain pathways compared to spontaneous laughter, which relies on older, more primal brain networks.

Laughter isn’t just socially significant; it may also be beneficial for our health. It releases feel-good neurotransmitters like endorphins and reduces stress hormones like cortisol. Research suggests that people who laugh more frequently may handle stress better and have improved cardiovascular health. Laughter is a universal human behavior, with even babies laughing before they can speak. While it might not cure every ailment, laughter makes life more enjoyable, strengthens social bonds, and potentially enhances health. Just be cautious if you have a broken rib—then laughter might not be so enjoyable.