What is "normal" behavior for adults?

Some time ago I made a blog post about "The Try Guys", which is the YouTube channel of four men who act like stereotypical little girls, in a very exaggerated manner, for no rhyme or reason. (And it's not like they are doing some kind of parody or playing a role. They seem to be "genuine" in their demeanor and behavior.) Adult men don't normally behave like this. Adult women don't normally behave like this. Even very young boys don't behave like this. Some little girls might behave a bit like this. It's very unusual and extreme immature behavior.

I got reminded of this when I recently watched a video by Pentatonix, The Prayer, which is nice and all, but I couldn't help but notice their somewhat similar demeanor and way of speaking at the end of the video. Not even close to the extent of The Try Guys, but still much more than is normal and usual for adults. Even the deep bass singer behaves like that there. (They don't behave exactly like little girls, but still the behavior is quite childish.)

This got me thinking: Someone could ask "what do you consider 'normal'? Why do you think this is not 'normal' behavior? Who gets to tell what is 'normal' behavior for adults and what isn't?"

This isn't a question of prescriptive "normality", as in "this is how you should behave, and if you behave in a very different way you are weird and abnormal". It's just an observation. This is not how the average adult human behaves, talks, acts like.

What could be considered "normal" is what the vast, vast majority of adult humans naturally gravitate towards in most if not all societies, during the entire history of humanity, even those that have been completely isolated from each other (and thus there can't be any cultural influence).

If you look at pretty much any culture or civilization, no matter which area of the world or which time period, you will usually find very similar patterns of behavior for adults who interact with others, especially people they don't know, or people who they have respect for. There's often a high degree of decorum and a degree of stoicism (ie. limiting how much emotion you show outwardly).

In fact, and quite notably, in many cultures a child is expected to change his or her behavior when he or she gradually becomes an adult. The behavior of the person becomes more mature and less childish. His or her speech (usually) becomes more intelligent, and the demeanor more toned down and stoic (even in the case of women). Perhaps not completely and absolutely stoic, but much more so than the behavior of a small child. This is not necessarily an imposed prescriptive rule but, once again, an observation. People see that all people around them become like this when they grow up, so they end up expecting it, and taking this change of behavior as a sign that the person is psychologically becoming an adult and is not a child anymore.

I wouldn't be surprised if there's actually an evolutionary explanation behind this change in behavior. Adults need to communicate and interact with each other in a more restricted way in order for a society to function properly. In fact, there may even be an advantage in strong emotions being unusual, because an adult outwardly showing strong emotions is usually a sign that something unusual has happened (either positive or negative). Perhaps something extraordinarily fortuitous event happened, or perhaps some kind of disaster or even danger. Especially this last one might be an evolutionary survival mechanism. In other words, it would be the evolutionary equivalent of "not crying wolf": If someone who is normally quite stoic looks unusually distressed and agitated, it may be a sign that something is very wrong and needs to be paid attention to. In contrast, if someone is always showing extreme emotions and behaving like a small child, when a serious thing happens people may take it less seriously because that's how that person always acts anyway, so there's little difference.

Of course just because something about our behavior or culture has an evolutionary explanation doesn't always mean we should just blindly accept it and follow it without restriction. There are examples where evolutionary instincts are better restricted in modern society. However, I would say that this is not one of them. There's no reason to try to actively restrict the natural stoicism that people develop when they become adults. People should behave with a certain degree of decorum, dignity and stoicism. This doesn't mean you can never show emotion, but it's better to reserve strong emotional behavior to when it's actually called for.