There are two innate fears that every baby is born with; a fear of sudden loud noises and a fear of falling. I don't advise dropping a baby any time soon in order to observe its fear reaction, but try popping a balloon near one of the little critters and see if you don't upset it some.
Of course, these fears don't stay with us forever, as evidenced by adrenaline-junkies who throw themselves out of planes and off cliffs. Nutters. As for sudden noises... who doesn't still jump out of their skin when the phone rings unexpectedly in a quiet room? Fortunately, for the vast majority of us, the call hasn't been placed by a psycho with an Edvard Munch obsession who's been watching us make popcorn all evening, thus meaning that the sudden start we are given is danger-free. Of course, those of us who have to deal with regular calls from the double glazing salesmen would probably prefer psycho-boy. No, I don't need double glazing, thanks. Or triple glazing. No, I'm good for conservatories too, thanks.
Fight or Flight
So how is it that a freshly-hatched human with a blank life experience slate is already able to react to two different stimuli with a fear response? In fact, what is a fear response? It's more commonly termed 'the fight or flight' response, i.e., measures that your body puts in place on sensing possible danger so that it can prepare itself to attack or defend (fight); or run away like its tail's on fire (flight). There is probably no one alive who wasn't born in a coma who hasn't experienced this, so I'm sure you'll recognize the symptoms as I list them:
- Pounding heart
- Tense muscles
- Cold, clammy hands
- Nausea
- Diarrhoea
Of course, there are those that say it should be the three 'F's: fight, flight and (to put it politely) fornication. Who hasn't at one point in their life spotted someone across the room who they have a MAJOR crush on and felt instantly nauseous and broken out in a sweat at the thought of talking to them? These symptoms are all caused by the release of adrenaline (epinephrine) and noradrenaline (norepinephrine) from the adrenal glands located above the kidneys. The adrenal glands are stimulated by the hypothalamus in the brain, which in turn has been stimulated by the amygdala, which has itself been stimulated by a perceived event in the immediate environment such as the tapping of a branch on a window pane or a sudden movement caught out of the corner of your eye.
The Amygdala
The brain circuitry involved in this whole process is quite complex, but the boss of the situation is the amygdala, Greek for 'almond'. It is an almond shaped nucleus located in the temporal lobe, and is part of the limbic system. It is the centre of a nexus of various brain pathways that are designed to pick up potential danger signs in the surrounding environment. The amygdala is a very old piece of neural matter, evolutionarily speaking, and (like a lot of the brain) outdates the development of conscious thought by many millions of millennia, which is thought to be why such things as irrational fears (phobias) exist. The amygdala's main function appears to be the determining of the significance of environmental events, and if necessary, trigger an emotional and physical response. It's not hard to see why the development of the amygdala was a boon to life; any creature that possessed the ability to react to a potential threat was more likely to survive than the ones that just sat there without a care in the world (and were quickly eaten / squashed / used as building material for something's nest.) We know that it is the amygdala that is responsible for determining the potential threat significance of events because of experimental lesions in animals, and from observation of behavior in humans after severe head trauma.
Back to those babies...
So a newly-popped sprog has these two fears from the word go because these fears have millions of years of evolution behind them. Okay, so a baby isn't actually going to be able to do much about a perceived threat (apart from lie there and poop at them), but by crying out, its parents become aware of its distress and will make efforts to appease it. Of course, it isn't just human babies that have this, the entire mammal collective do, as well as birds and reptiles. In fact, the stegosaurus, with its walnut-sized brain, probably had an early amygdala prototype. It's been around the block a few times.
So, fear is an evolutionarily advantageous way of ensuring an animal will avoid certain dangerous situations. A fear of the dark is, for most of us, an irrational fear, but was previously very important in human survival. But now, to be scared to walk into your bedroom without the lights on is just plain irrational, assuming you haven't just had an argument with your Other Half and they're waiting in there with something sharp. But millennia ago, when we didn't have houses with brick walls and security fences; and hadn't hunted virtually ever other predator into extinction, we were very vulnerable in the dark. Especially since all the now-extinct predators had better night vision than us. Interestingly, I have heard anecdotally that males tend to be scared of the dark around them, such as in the wardrobe, and females tend to be scared of the dark beneath the bed. The reason postulated for this is that women, being lighter and lither than men, were able to climb trees to sleep in at night, and so danger would generally come from below. Meanwhile, men, being the slow, lumbering beasts that they are, had to sleep on the ground at night and so had to be wary of the surrounding environment. Me, I think that evolutionary psychologists have too much time on their hands and should go get a proper job.
Fear conditioning
So, we're born with but the two fears. How do we accrue more as we get older? There are two memory circuits that are key in fear conditioning; the conscious memory from the hippocampus; and unconscious memory from the amygdala. For instance, someone might develop a fear of enclosed spaces because of a childhood experience of being trapped in a cupboard during a game of hide and seek. The kid would start to panic and hyperventilate because it thinks it's never going to be found and is going to be stuck there forever more. The conscious memory of the experience would be converted to long-term memory by the hippocampus, and the amygdala would note that being trapped in a small space is threatening situation that should be flagged for the future. Summed-up: the experience of a nasty stimulus in combination with a certain event will sometimes lead to a fear of the event itself. So, the next time that the child is in an enclosed space such as lift, the amygdala will determine that a the current environmental experience is suspicious enough to set off a `fight or flight' reaction.
A personal example that I can give you is my fear of walking down stairs. I didn't even know I had this fear until recently. Yeah, I know, I'm all kinds of nuts. Anyway. I was an ungainly, uncoordinated lump of a child, and I once managed to trip over my own feet when coming down a flight of stairs. Lying in a crumpled heap of pain at the bottom, my amygdala made the spot-on observation of "Ooh! That hurt! Let's not do that again, eh?" Now, as an ungainly, uncoordinated lump of an adult, I'm always aware of what I'm doing with my feet when walking down stairs. No biggie, not disabling... unless of course you have the fool idea of doing the Inca Trail. Those Incas really liked their stairs; put them everywhere they possibly could. Admittedly they lived in the Andes, but that's beside the point. The first two days of the full hike is uphill all the way, which apart from being not-quite-as-fit-as-I-thought-I-was, wasn't a problem. The third day is a little more uphill walking to get to the top of the second peak, and then it's mostly downhill from that point onward. I mentioned the Inca's fascination with steps... suddenly, I was faced with a steep downward flight of stairs that had about 6" of foot length on each step, with each step being half a leg deep. Oh, and they were only slightly wider than I was, and there was a 3000ft drop to my right. It was at this point that I sat down and refused to go any further. There was a lot of tears, a lot of cajoling from my friend and the guides, a lot of false starts and a lot of me having to swallow my pride and shuffle my arse down step by step. Not one of my finer moments.
What I've just relayed is of course a completely over-exaggerated fear response; the level of perceived danger was greatly in excess of the actual level of danger I was in. Probably. I am quite clumsy. The name given to such an over-the-top reaction is 'phobia', and a phobia can be specified by a prefix, such as arachnophobia (fear of spiders) and paraskevidekatriaphobia (fear of Friday the 13th).
Fear Dysfunction
An overenthusiastic amygdala is responsible for a great deal of psychiatric disability. Apart from phobias, which are far ranging (arachibutyrophobia, the fear of 'peanut butter sticking to the roof of your mouth' anyone?), there is post-traumatic stress disorder (PTSD), obsessive-compulsive disorder (OCD), panic attacks and generalised anxiety disorder (GAD). It is estimated that around 50% of mental difficulties are anxiety related. In PTSD, the amygdala responds to a severe traumatic incident (such as torture) so ferociously that even day-to-day activities will trigger flashbacks and paralysing anxiety.
There must be some genetic basis to amygdala function; this is evidenced by the way that some people are anxious about anything and everything, and some don't even know the meaning of the word 'worry'. Anxiety is a trait that runs in families, but this could as equally be nature as nurture. Interestingly, MRI scans show that those with bipolar disorder tend to have larger than average amygdalas. The reason for, and effects of this are not clear.
The reason that the amygdala can exert such a strong influence is because of the way it communicates with the rest of the brain. It projects ten times as many neurones to the neocortex and other structures than it receives as inputs for these other areas. This means that there is very little feedback control available to the rest of the brain, as evidenced by someone who is unable to stop themselves from avoiding stepping on cracks in the pavement, even though they rationally know that their mother won't come to any harm if they do so.
The only successful method that has been proven to help with irrational fears is cognitive and behavioral therapy (CBT). Cognitive therapy attempts to stop the vicious cycle of thoughts about a situation that worsen said situation by identifying, analysing and rationalising the thought. In doing so, a patient can gradually break the obsessive thought cycles that they find themselves locked in. In behavioral therapy, patients are first made to analyse in great detail the behavior they want to change, and then gradually expose themselves to the situation that they find threatening (systematic desensitisation), in combination with being taught anxiety reduction methods.
CBT is very effective, and is in fact as effective as pharmacological therapy for GAD and mild to moderate depression, with the added advantage of no systemic side-effects and a reduced likelihood of relapse. So, the lesson to be learned from all this? As with all things in life, fear is good for you in moderation. However, when it becomes all-pervading, it can be a chronically disabling condition. Really, the only thing anyone should be afraid of is fear itself. Oh, and this.