Recall from the general anxiety section that anxiety is an evolved protection system. You're hiking in the woods, you see a mountain lion, your inner guard -- your secret service agent -- goes haywire and prepares your body for battle. Among other things, it elevates your heart beat, produces tunnel vision (to better focus on the threat) and produces sweat (to better slip away). The two criteria the secret service agent uses to assess the threat are 1) how strong you are compared to the threat and 2) what would happen if the feared event (i.e. getting pounced upon) actual occurs. The weaker you feel compared to the mountain lion and the more harmful the worst case scenario is, the more anxious you'll end up feeling.
Our anxiety response system was designed to deal with ancient, not modern ones.
Our anxiety system developed when we were in the stone age. It was well suited for the threats of that era. But now, in modern times, it just doesn't suite us as well. The sweating, rapid heart beat, and tunnel vision that can help evade a mountain lion doesn't help us at all against a modern threat, such as a multiple choice test, or an airplane trip, or an attempt to go approach that girl over there.
Now you might be thinking, "hey wait, it makes sense for my body to react this way to protect me from a mountain lion, by why do I freak out at a party?" After all, it's just a group of random strangers, many of whom you might not ever seen again anyway, right?
Remember, most of our mental systems evolved in the Stone Age. This explains why today we're so overweight as a society. We evolved to deal with food shortages -- quite common for our ancestors -- by packing on the pounds when food was available. In our modern world, where food is now always available, we still keep packing on the pounds while our body, always preparing for a potential famine, readily resists any effort to burn up excess fuel.
In ancient times there were less people and less civilized discourse. Back then, rejection could have dire consequences.
Consider that back in the Stone Age, there was no such thing as a Los Angeles. In fact, anthropologists note that most of our ancestors lived in packs of no more than 15 or 20 people. What would happen back then if you were kicked out of your group? It probably meant death. After all, you probably wouldn't be able to survive on your own without the help of others. If you tried to join some other group, it's likely they would be wary of outsiders -- they might kill you on the spot! So there was a strong desire to remain a member of the group. And with each group, there were only so many resources to go along. There may have been a constant theme of proving yourself to show that you were worthy of being included in this small community.
Of course, we don't know exactly what it was like back then. But we do know that this is often what happens when there are small groups that must band together to survive. We see a similar behavior in wolf packs and in groups of primates in the jungle.
In such a group, there would undoubtedly be a desire for men to show that they were productive and capable. There would be a desire for women to remain connected and have strong social bonds. Everyone would have a desire to be seen as good at what they do, to be seen as a contributing member of their team. We see this today. Soldiers, policemen, and firemen will sacrifice everything for their group, their team. And everyone, be it a cop, a mom, or a janitor likes to be seen as good at what they do.
Just as everyone aspires to be great at what they do, a common fear is being sub-par and being exposed as a fraud for it.
The flip side of the coin is that there will be a common fear, a fear of being seen as not good or not a worthwhile member. An extremely common fear in people who have social anxiety is the fear of being seen as a fraud. After all, what happens if you're on an island with a small band of people, your job is to be the fisherman, and it's discovered you're not good at catching fish at all? If it's like the TV show, you're voted off! And back then, the result of being voted off can be just as bad as the result of being stalked by a mountain lion. Thus, our body uses the same response system to handle a group of angry village people as it uses to handle a mountain lion, complete with racing heart, sweaty palms, and tunnel vision.
The problem, of course, is that we live in a modern world where threats are not best dealt with by a rapid heart beat or profuse sweating. Yet it's still our instinct to view the world in terms of the Stone Age. We tend to see our group not as a massive city with 4 million people but of a small town with 20 people.
To take an example of this, suppose you're at an airport, you're single, and you have an hour to kill before a flight. While waiting you happen to see an attractive person (guy or girl) at a local coffee shop, sitting alone. You have nothing but time and would like to approach the person. Do you do the approach? Of course not! The moment you do, you feel a sense of anxiety, perhaps dread. You rationalize your inaction. Maybe you try to think of some indirect way of meeting him or her.
In the modern world, this makes no sense. Let's say you approach him and he rejects you. What have you lost? You'll probably never see him again anyway. You'll probably never see the other people in the coffee shop either and, if anything, they would only appreciate your initiative. Let's say it's a she and after a few awkward seconds her boyfriend approaches. He's certainly not going to get violent just because you approached her to start a conversation.
Social anxiety begins to make sense when understood in the context of the Stone Age world.
But in the Stone Age it would make sense to feel apprehensive about approaching. Why? Let's say you're a male, a caveman, and you live in a Klan of twenty people. Let's say in this clan there are 10 women and ten men. You're looking to find a mate. Of the women, perhaps two are probably too young, and three are too old. That leaves five women for you. Let's say you approach and you do it poorly. Who is she going to tell? Well, probably her four friends, who will then want nothing to do with you! Now you have no chance of passing on your genes. And if she has a boyfriend, he's not going to be a civilized member of modern society, with the fear of God and the airport policemen. He'll take it as a personal affront and it will be him and his friends against you.
You're giving a speech at a wedding. In the modern world, most people won't remember your speech anyway. If you don't do a good job, no one is going to care. But in the Stone Age world, if you're supposed to be smart and capable, and you give a bad speech, you'll lose a lot of status. And when resources are slim, status means everything. Who wants to be friends with a person who doesn't have status or resources? If you end up offending someone, they might just attack you on the spot. Better not put yourself out there. If you do, you'd better be prepared to run away, and quick. Better to have a rapid heart beat, tunnel vision, sweaty palms to run away. And there you have social anxiety.
Social anxiety exists to protect us from ancient threats of social rejection, which often meant being attacked or being completely rejected by society. But this social anxiety is no longer useful in the modern world. Hence, what used to be adaptive is now considered a disorder, specifically, social anxiety disorder.