Self-consciousness in humans
Animals may withdraw, hide away, and lick their wounds, but few are ever felled by existential despair. It seems that burden of clinical depression falls to humans alone.
The answer to this existential irony may well be the irony of existence itself:
Humans alone have self-reflective consciousness, and it is here that depression takes hold.
Animals act by instinct, and so do humans, but we have the intermediary of consciousness, and with it the ability to decide. Most of the time our instincts seeking food, company, or pleasure are beneficial, but sometimes our drive towards action is pointless or even harmful: we may be sick, trapped, humiliated, powerless, or grieving.
Our genes response
At this moment of weakness and vulnerability, our genes have learnt over aeons that the best bet is shut down and withdraw. To get a human to act a certain way consistently, evolution uses automatic thoughts and emotions such as hunger and the pleasure of food driving us to eat, or lust and the pleasure of intimacy driving us to procreate.
When it is time to withdraw, these drives shut down just as they do in animals, but with humans there exists the additional sphere of consciousness.
Often consciousness can spur a human to act against the protests of fear, fatigue, or hunger to seek a higher goal, and so to produce a true withdrawal response, evolution must find a way to neutralise our conscious drives also. Evolution must produce a full 180 from our usual thoughts and feelings and deliver a complete behavioural shutdown.
The experience of this is clinical depression.
Unsurprisingly the thoughts and feelings involved are horrible: loss of energy, appetite and pleasure; worry and dread; the inability to act or make decisions; aversion to other people, and thoughts of helplessness, futility and doom.
These are ‘symptoms’ but also a body / mind reflex that forces a person to retreat and conserve resources.
From this view, depression is the brain’s fail-safe to whisk you away from the arena of competition to avert further damage.
The reason why depression is a helpful reflex in animals but a painful burden in people is the peculiar human quality of consciousness.
Yet there is something more to human depression that any patient or clinician knows too well: depression is often far worse than any temporary strategic retreat.
Depression often hangs around for months or years, far, far exceeding in both time and scope any initial usefulness. This extended course is almost entirely absent in animals: once the trigger departs, so too the response.
In humans it stays, often becoming more damaging than whatever caused it. The basis of this peculiarly human curse is again the fact of consciousness. Since humans experience all the painful thoughts and feelings that cause or accompany the withdrawal response, they linger in memory and can act as depressive triggers in their own right.
Being depressed is depressing, and thus begins a vicious circle.
Meanwhile animals lack the niche of consciousness where depression can take root. Triggers for their withdrawal are all external, so when food returns, the predator wanders away, or wounds are healed, the reflex switches off, and the animal bounds back into action.
The external triggers for human depression may also vanish, but by then it has replicated internally, its dark tendrils slinking into memory and perception. The switch stays on.
Say a man loses his job. The loss, humiliation, and helplessness, along with the threat of an unknown future all trigger a depressive response. Initially, it is helpful to stay home, rest, and reflect about what went wrong. So far this is as self-protective as an lion’s withdrawal after a defeat.
But what happens next is distinctly human.
The loss and humiliation lodges in his mind. He loses confidence. He has an image of who he was and what he had, he looks around at his changed life and becomes painfully aware that it has gone.
That awareness of our own misery (litost in Czech) is the unique human feature that gives depression an internal power source just as vivid and real as the external world – and it does not easily shut off.
Phil’s self-esteem falls, his activities dwindle, he becomes isolated, and the dark hue his perception casts upon the world makes his former life seem so far away, and fading fast. The humiliation deepens, the sense of being trapped rises, and grief accelerates. His internal shadow becomes a self-fulfilling prophecy as he loses friends and alienates his wife.
Now things are truly spiralling, and a helpful reflex has become a disease.
The changed world
In the world where our ancestors evolved, the conditions prompting the depressive reflex (famine, winter, defeat) tended to be temporary, so it would switch off like in animals, and life could resume. But the triggers of modern life (such as a humiliating boss or a miserable marriage) are subtle and harder to escape, or even worse lodge in memory and even identity (regret, trauma, disillusion) and endure.
After certain point, depression has done enough damage both externally (isolation, unemployment) and internally (pessimism, self-loathing) that it can runs purely on its own power.
From inside, depression seems perfectly justified even when its causes have passed. Loss, humiliation, entrapment summon the noonday demon, and then it brings its own, with interest.
No shark or bird ever felt depressed, a hunter gather rarely does, but modern man does all the time.
By becoming less vulnerable to external threats we become more vulnerable to internal ones.
Immune system and evolution
We can see the same pattern throughout evolution, such as in the development of the immune system. The earliest organisms have only the most basic defences, like a sturdy outer wall. More complex organisms need more complex defences, but now these can turn against the very thing it evolved to protect.
Immune cells rapidly identify an infective threat and declare war, releasing a cascade of chemicals that activate the spleen and lymph nodes like factories switched to munitions production. The alarm is carried to all parts of the body, summoning more cells to the cause, pumping out antibodies, activating killer T-cells and rousing the macrophages – literally “big eaters” – to engulf and digest the invaders.
Meanwhile the hypothalamus raises body temperature, hoping the infection hates this even more than we do. All this is good, but what if after a week, two weeks, three weeks, the infection is long gone but the immune system is still at DEFCON 1?
Now the immune system is the enemy, the palace guard in revolt.
When immune system misfires
Patients often die not from the infection but the defences running amok, spiralling the blood pressure and shredding the smaller vessels. Asthma, allergies, or arthritis are less dramatic examples of natural defences triggering beyond their mandate.
One interesting feature of depression is that the cause is usually not a large, single event (like a car crash) but more subtle, enduring effects over time, such as an oppressive marriage, a stressful job, or loneliness – often in combination.
Here the depressive triggers linger externally and eventually internally also. The situation is akin to stress leading to hypertension, and ultimately strokes and heart attacks. Under stress, vessels constrict and our heart pumps harder to raise our blood pressure, which enhances our ability to respond in the moment. The problem is when this ‘war footing’ remains switched on indefinitely.
Depression is just like this: a helpful natural response left on too long and therefore gone rogue, made possible by the unique quality of consciousness where it can take hold.
This is the new, evolutionary view of depression, and the next issue we will discuss how understanding the depression reflex can offer new insights to dealing with it.