Darwin and Fear

In his wonderful book 'The Expression of the Emotions in Man and Animals', Charles Darwin tries to explain the evolutionary advantage of the reactions we have to various situations, like those of grief, anxiety, helplessness, surprise and fear. He compares our behaviour with similar responses in animals, concluding that many emotional reactions are shared with other species and have useful functions, such as helping us to react quickly in a fearful situation.

He makes a useful distinction between 'fear' and 'terror'. He suggests that the word 'fear' is appropriate for our reaction to something sudden and dangerous. He uses the word 'terror' for extreme fear, in which there is trembling of the vocal organs and shaking of the body, like Zeron experienced. Nevertheless, whether it's 'terror' or 'fear' it's still an unpleasant emotion.

Darwin observed that when we suddenly become scared, our mouth often opens. He argued that an open mouth may have the advantage of allowing us to breathe more freely in preparation for 'fight or flight'. He had realised that many of the expressions we use, and the reactions we have to fear, have been conserved through the generations since prehistoric times - in fact, probably since before we were human.

Together with cold sweats, the ceasing of anal sphincter control (yes, people do shit themselves with fear), and the erection of bodily hair by 'the muscles of fright' (minute, involuntary muscles, which run to each separate hair follicle) - we have lots of vestigial, or "leftover", fear responses from our prehistoric ancestors. The best example is that bristling hair. It is still believed that our hair standing on end is a throwback to when our ancestors had fur. Darwin explains it as follows:

"With respect to the involuntary bristling of hair, we have good reason to believe that in the case of animals this action, however it may be originated, serves, together with certain voluntary movements to make them appear terrible to their enemies, and as the same involuntary and voluntary actions are performed by animals nearly related to man, we are led to believe that man has retained through inheritance a relic of them, now become useless."

One point Darwin missed is that hair standing-up on end is not totally useless; they will be more sensitive to air currents and pick up movements of a predator - or enemy - through the detection of a slight breeze or draught.

Of course there are some things that Darwin couldn't quite explain - for example, why people cover their mouths or the top of their heads when startled, although he did note that "the hand being placed over the mouth or on some part of the head has been observed in so many races of man that it must have some natural origin".

It's possible that placing the hand over the mouth may be to reduce the sound our breathing makes - reducing noise that can be detected by an enemy/predator. Having the hands above the shoulder near the head, might also help to protect this vital organ, or if we are attacked, they might be useful in this position to provide force and accuracy when moved downwards to hit a predator or enemy. They also provide balance in case sudden movement is required.

So what's the point of all this in a programme about the origin of fear? Well, there's so much evidence suggesting that our reactions to fear are comparable to that of distant ancestors and primitive animals, that it can help us pinpoint where the feeling comes from. It must be the primitive part of our brain - the 'lower brain' - which is responsible for our rapid response to fear, as the 'higher brain' only appeared comparatively recently in our evolution.

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