In this article, I will try to sum up some evolutionary theories of depression. Have people always been depressed, or how is it?
What is depression?
Depression is the down-regulation of positive affects to put it simply. Everyone knows about it because depression and anxiety disorders are the most widespread psychological disorders.
People are getting anti-depressants to make the regulation of positive affect stable so that they hopefully regain the ability to experience positive states.
You cannot ignore the fact that anti-depressants is a billion dollar business, but indeed it is a cost for society as well. So why is it exactly people are getting more depressed, or are they? I think some of the reason is due to the way our society is constituted, and here the modern competitive work place is to consider as well.
Even though civilization has brought numerous advantages and comforts, there are downsides to it as well. Since so many people get the diagnosis of depression, one needs to ask the question, why it is so.
A review by Gilbert (2006) provides insights to the evolutionary explanation of depression. Can the evolutionary phenotype variation account for the variability in moods and emotions? These are some of the questions that evolutionary psychology tries to answer.
There is some evidence to suggest that the genes play a significant role in depression, and especially the combination of a specific set of genes and a fragile environment seems to trigger the onset of depression.
A proper and caring environment may alter the gene expression so that depression does not manifest itself (see epigenesis). Let’s look at some of the social, evolutionary explanations of depression.
Evolutionary theory of depression
1. Social defeat and social harassment
Social defeat and social harassment might account for depression-like symptoms in humans. According to this theory, the reason why depressive thoughts occur is that (1) the individual down-regulates his goal pursuits so that he avoids challengingdominants such as a competitivemale that will make the person lose a sexual relationship or resources of any kind.
In other words, the depressed person is interested in keeping a low profile so that he won’t get into trouble. Another reason (2) for the down-regulation of emotions may be to influence a dominant other’s mind, so that the dominant accepts a submission and therefore does not see a threat.
2. Social support
Social support given by others plays an important role in regulating negative states, and therefore the environment is of huge importance to the resilience of depression. Affiliations might stimulate oxytocin, which can inhibit cortisol and therefore lower the stress hormones. This might produce positive affects in turn.
In general it is found that the impact of various failures depends on the quality of relationships and representation of others. This will affect the way we evaluate ourselves, and typically the more social support we perceive we have, the more positive the evaluation will be.
Depression has probably evolved as a defense strategy that seems to have its origins in our pre-human ancestors. We have always been competing about resources, and this competition has sometimes turned out to be a loss for some. The loss would possibly trigger depressive emotions to inhibit one from attending (bigger) losses or fights in the future.
3. Adaption vs. Maladaption
An important point to make is that not all psychological disorders are adaptive in all environments, even tough we have undergone an adaption through the evolution.
The threat detection-response system can overwhelm logical thinking, because often emotional expression is not well seen (e.g., at the work place), but this inhibition of emotion might increase the same emotions in the long run.
Depression has been linked to the capacity for self-reflective thinking, and since it is so we are able to trigger depression by our own negative thoughts and images.
The excitement that comes by the mere thinking about a fight is an adaption so that we can prepare for the fight mentally, but this might affect our emotions in a negative way since we might think on a negative episode over and over again.
Our cardiovascular system is exposed to huge threats by high fat foods, low exercise levels, and smoking habits. The diet of many people is low on omega-3 which is thought to be a risk factor for depression.
There is increasing awareness of the impact of modern chemicals and their impact on mental health in general. Many of these factors seem to have changed from our ancestors’ to our contomporary society, and this is something we need to be aware of.