To this day, science has yet to truly figure out the origin of laughter. We know the benefits of laughing and we why should laugh, but not many people can explain why it is part of our nature. This article will provide a possible explanation for this bizarre phenomenon.
Let's begin with understanding why we have certain characteristics and innate behaviours. Natural selection favours those individuals which have the right physical and behavioural characteristics for surviving in a certain environment. Cheetahs have been selected by nature to survive because they are capable of hunting down food using their tremendous speed. Bears are selected by nature to survive because they have the ability to hibernate which helps them survive in their environment during long winters. Natural selection is a very simple model. If we compare two human males in an environment where speed is needed to hunt animals and survive, the faster male will be able to live while the slower male will die. The faster male will then reproduce and his kids will also be fast. Over time, the population of humans in that environment will all be quick on their feet. This is how evolution works on a physical level. Humans are perfectly adapted to their environment, which is why we are still surviving. We have lungs which process oxygen, intestines which absorb fuel, and an excretory system to get rid of waste. These are just some of the adaptations we have as a species which allow us to thrive in our environment.
Now, lets consider how laughter relates to natural selection. I'm going to use fish for this example. Let's say I put two fish into an aquarium, and one of them was large and territorial while the other one was small and passive. Immediately, the bigger fish will bully the smaller fish through acts of aggression and by eating larger portions of the food available for both of them. The larger fish doesn't have to physically harm the smaller fish in order to kill it. The reason is, stress. The smaller fish will become stressed due to the aggression portrayed by the larger fish, and also because of how difficult it is to obtain food with the competitor around.
Stress is a major killer. A lot of us don't attribute illnesses and death towards stress because stress isn't what actually gets to you. What stress does is reduce the effectiveness of your immune system; it opens the gateway for bacteria and viruses to get into your body and cause harm. Any animal that is put under stress for long periods of time can easily become prone to several health problems.
The act of laughing evolved in our ancestors because it combatted stress. We as humans have an instinctive drive to do things that make us happy because it keeps us alive. Laughter evokes happiness, which induces the production of hormones called "Endorphins". Endorphins fight off stress and can help benefit our moods. A few examples of when your body releases Endorphins is after/during sex and after a long run (referred to as a "Runner's high"). The lack of stress means a better immune system and thus a better chance at survival.
Individuals that "laughed" often had better chances at staying alive longer due to their stronger immune system, and thus had the opportunity to procreate more (this is where natural selection comes into action!). Over time, more and more offspring would practice the act of laughing.
People say laughter is the best medicine because it really is the best medicine! A world without laughter would surely be a depressing one, to say the least.