“Pain or suffering of any kind, if long continued, causes depression and lessens the power of action, yet it is well adapted to make a creature guard itself against any great or sudden evil.”
For ages, our ancestors have known of the condition we call depression, though to them it was listed under a variety of other names: sadness and the blues, to name a pair. The question that they never asked, but scientists now seek to answer is: has there ever been any payoff from depression from an evolutionary perspective?
Depression is not a rare disorder by any means, and it is suggested that as many as 50 percent of Americans will experience the criteria for diagnosis with major depressive disorder at one point in life or another. It doesn't take a psychology degree to know that's a high percentage of people affected, particularly for a mental disorder. The majority of mental diseases are actually quite rare – how is it that depression slipped through the cracks?
For one, depression may actually have played a role in the process of natural selection regarding infants and young children, in the form of postpartum depression. It has been shown that parents will not invest sufficient care in every one of their offspring if the apparent costs outweigh the benefits of caring for certain offspring. Postpartum depression may be an evolutionary signal to a parent that risks involved in continued care of the unfit offspring outweigh the benefits, thus exacting a decidedly detrimental toll on the caregiver's health and resources. It may also be an evolutionary signal for assistance from others for help caring for the child.
Socially, it may also have helped contain sexually transmitted diseases, as depression frequently causes disinterest in social interaction and sex. In addition, exposure to other diseases would have been lessened by a reduced exposure to events and elements outside the confines of the afflicted's own home.
Plus, with a lack of energy and desire in even the most mundane things in life, our ancestors would have likely spent more time sleeping, which would have replenished the body in a time when stressful and excessive work conditions contributed to skyrocketing illness and mortality rates.
People with depression can focus on one issue and attack that issue as a whole, rather than breaking in down into bite-sized components, which is more taxing on the ventrolateral prefrontal cortex (VLPFC). Focusing on a number of problems requires a constant supply of neurons to keep up with the more numerous amount of tasks than can be accomplished by those who can digest the problem as a whole and concentrate solely upon finding an answer to that problem.
This is due to the presence of a receptor in the brain known as 5HT1A, which constantly fires new neurons for the VLPFC. Consequently, the subject can perform better in the functions regulated by the VLPFC, like focus and sustained concentration. Depression activates the VLPFC, while the 5HT1A sustains it vigorously to achieve its intended functions for longer periods of time.
This would have been a very valuable asset to our primal ancestors. Unlike us, they had fewer distractions to occupy their attention, though because of the volatility of their environment, every problem was potentially life-threatening. A chain of priority was absolutely necessary. A depressive mindset would allow our ancestors to take on the most pressing problem first, then adapt to the other problems facing them as necessary.
Another possible benefit is that by concentrating solely on the problem causing one's depression, one has a greater chance for true introspection and self-enlightenment. Many of the greatest sages in the history of mankind probably suffered from one form of depression or another, yet by channeling their focus inwards, they found a deeper enlightenment and the ability to better interact with their environment and problems in a more meaningful and positive fashion.
Perhaps the greatest asset of depression is the most evolutionarily necessary: depression forces the hand of the species to reach out and try to eliminate the suffering of the one for the good of the race. And maybe, just maybe, this response is what separates us from the rest of the animals.
Allison Gamble has been a curious student of psychology since high school. She brings her understanding of the mind to work in the weird world of internet marketing with psychologydegree.net.