Could there be an evolutionary explanation for depression?

File:Emmanuel Benner - Prehistoric Man Hunting Bears.jpg

Could there be an evolutionary explanation for mental health conditions such as anxiety and depression?

I have for a long time pondered over the hypothesis mooted by some that there may be an evolutionary explanation for both anxiety and depression. This explanation may also embrace seasonal affective disorder, and bipolar disorder.

Let’s start with anxiety. On the face of it, anxiety is fairly easy to categorise as an evolutionary response.

Imagine a tribe who live in mud huts next to a fast flowing river inhabited by crocodiles and surrounded by a dense jungle full of ferocious animals. This tribe have no fear whatsoever, and the children, just like their parents, take every opportunity to play in the fast flowing river and climb the trees in the jungle.

All, that is, but two people, a man and a woman who were born with this condition called anxiety. One by one the children and their parents get eaten either by the crocodiles or the ferocious animals inhabiting the forest. The couple with anxiety however, do not venture near the river or risk going into the jungle. Lo and behold they are saved because of their anxiety. In time they have children and so this condition us passed on and on through the generations.

Anxiety could be said to be one of the main motivating forces in much of human behaviour and provides a tremendous impetus to learning and adjusting throughout life. The earliest human remains that resemble us, is a female skeleton (Australopithecus) or should I say, several hundred bones known as AL- 288-1. She has been named Lucy” and she dates back some 3.2 million years and she is a hominid.

Lucy would not have fared very well when facing a huge wild beast; her nails could hardly be described as claws. Her hair, a little under her arms, between her legs and on her head could hardly be described as fur. Porcupines or their prehistoric equivalent had spikes that came up when they were scared. Lucy, on the other hand, had goose pimples and a few short hairs that stood up on end, hardly a match. She was not very strong and could not really outrun her enemies. So how then did she fare so well?

Well, she had two special gifts: a brain that could think and reason in a way that her enemies could not, and hands that had fingers and movement far more sophisticated than them. She soon learnt how to fashion weapons with her hands. This fantastic evolutionary condition called anxiety enabled her to identify threat.

If we were really being picky we might say that anxiety does not mean precisely the same as fear. Fear arises from threat, by some situation outside a person, that can be assessed and acted upon. Fear prompts us to either attack or run away. The sophisticated autonomic nervous system, ( the sympathetic and parasympathetic nervous system) in conjunction with the endocrine glands prepare the body for “fight or flight.”

There are several other states associated with fear and these include “freeze,” like a rabbit does when in a car headlight, and another we shall call “flop,”  – in this latter state, blood pressure, which is sky high when in the fight or flight state, literally drops in an instant causing us to faint. An example where this might come into play is where you are running away from your attacker and you are caught by a huge blow and a gaping wound prevents your escape. Unable to fight or flee, a message is sent to the brain in an instant and a rapid drop in blood pressure causes you to faint. Lying motionless, hopefully your pursuer just might think, ” ugh, dead meat, that’s it, I am not interested any more.” Another related state is known as “fawn,” – in this state, showing extreme affection and getting friendly with your attacker, you might be able to favourably influence your fate.

Coming back to anxiety, let us say that it is a feeling of unease or concern in relation to a perceived threat. This was the gift Lucy had. Her fairly small brain was programmed to look out for threat. That is why today we are fixated with the new bulletins and we gravitate towards news stories which have an element of shock and horror. Yes, Lucy could have been programmed to remember the kiss and cuddle she had with Freddie Flintstone, but no, she was programmed to look out for threat and danger. Today, we can be forgiven for being drawn towards gossip, after all it important for you to know if any dangerous predators are moving into our neighbourhood!

One could almost say that we are “over-engineered” to look out for danger; in other words, just like a car alarm that goes off with the slightest vibration from a lorry passing by, or a burglar alarm going off when a spider walks over it, we too are sensitive to all forms of imagined threat or danger. Hence we get “panic attacks” at the drop of a hat and our body kicks into “fight and flight.”

Depression too, could be viewed as a natural response to overwhelming odds or abnormal situations of stress. Imagine if you will, our prehistoric ancestors living in a   cave by a river, close to the plains populated by wild animals. The weather is particularly bad for a prolonged period, dark skies and rain cause the rivers to flood. As a consequence of the poor conditions the normally dry plains flood and the wild animals now are on the prowl for food.

Looking out for threat and danger, the dark oppressive skies signal to us that something is wrong and that we need to withdraw. Perhaps the modern day incidents of seasonal affective disorder hark back to this time? Chemical changes alert us that something is wrong. Could bipolar disorder signal to us to get hyperactive and gather what supplies we can before depression kicks in?

With danger imminent our body chemicals signal both brain and body to withdraw. With lowering of energy levels we do not feel like doing anything much, loss of libido means that we are no longer making babies, so no more extra mouths to feed! No need to go far to hunt as our appetite is diminished and our hastily gathered supplies will last us through this period of danger. With little energy to do anything, not even washing or dressing, we huddle up together under a pile of animal skins and hibernate, sleeping though until the spring and the nice weather arrives again. As it does, so the skies lighten, floods recede and the animals move back to the plains once again. Safety has returned and our mood is restored back to its former state.

Fanciful perhaps, but there may be a grain of truth in there somewhere, who knows?

Until next time, best wishes Steve.

 

You may wish to know that Steve is now offering therapy sessions via Skype                       Please contact us through our website @  www.stevecliffordcbt.com

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Steve Clifford                                                                                                                             Senior Accredited Integrative  Psychotherapist.                                                                   Accredited Cognitive Behavioural Psychotherapist.                                                                                                                                                                                                                   Image ref: http://commons.wikimedia.org/wiki/File%3AEmmanuel_Benner_-_Prehistoric_Man_Hunting_Bears.jpg

 

 

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