Adapt or Die | Evolutionary Biology and Maladaptive Traits
Traits. They're in our genes. They define our propensity to adapt and respond to stress and disease. Traits allow us to innovate solutions to meet our needs. It's what evolution is all about. According to evolutionary theories first described by Charles Darwin in his book "On The Origin of Species" (1859), traits survive throughout time, descending from generations past in-order to promote the survival of our species. And those that don't benefit our survival are weeded out of the human genome one by one until the trait is extinct. So why have maladaptive traits such as depression continued to manifesting throughout our generational history at alarming rates? According to Darwin (and accepted by the scientific community for it's validity), any trait that continues to thrive throughout our evolutionary history must have some functional advantage to our survival.
Major Depression Disorder | Prevelance Across Entire Lifetime By Birth Cohort
Despite more and more efforts to lower the prevalence of depression, there is an increasing risk in each birth cohort. Looking at older generations, you can see only 10% of people now in their 60's and above have ever experienced depression in their lifetime. In each birth cohort the percentage of people who experience depression is higher with each generation- in our youngest cohort of emerging adults the percentage is highest, and alarmingly within the shortest amount of time. And despite a 300% rise in anti-depressant use, the depression epidemic only continues to get worse.
Are you feeling down? Get outside and watch a songbird!
"A study by University of Queensland in England found that lower levels of depression, anxiety and stress were associated with the number of birds people could see in the afternoon. In the study, common types of birds including blackbirds, robins, blue tits and crows were seen. The study, involving hundreds of people, found benefits for mental health of being able to see birds, shrubs and trees around the home, whether people lived in urban or more leafy suburban neighborhoods."
What is the Function of Depression?
Now, the conundrum: If you look at the majority of research asking this very same question, the simplest answer is that the evolutionary function of depression is to kill us off. This may be an exaggeration, but according to the conclusive evidence of a wealth of research data , the common consensus doesn't look too good for the future of our species. There are many factors to consider in compounding the threat depression poses on every generation of humanity. Justifiably so, inescapable genetic and environmental risks negatively frames depression as an epidemic requiring intensive intervention and preventative measures. There exists a collective attitude to improving the lives of the individuals who are suffering, but to also preserve the health and benefit of society as a whole. Identifying the reasons depression may manifest in an individual only uncovers the complexity of deeply intertwined exposures within our social and personal experiences. Factors such as family history, stress exposure both in utero and throughout life-stages, trauma, resilience and personality thresholds, sickness and disease, bodily responses to diet, pollution and the proximity to trees and birds in urban environments; and many many other factors all contribute to depression.
Depression Barriers To Suceed And Thrive
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Only 33% of Americans report that they are happy
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Depression is the number one cause of disability worldwide
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80% of new mothers develop major postpartum depression
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Every 80 minutes there is 1 depression-related geriatric suicide
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Depression is a major risk factor to developing cardiovascular disease, the #1 killer among both men and women
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Children and adolescents with depression experience low self-esteem, guilt, feelings of worthlessness and frequent absences from school and activities
The Body-Mind Connection | Inflamatory Response In Depression As Predictors Of Modern Illnesses
In the last decade, several studies have been published describing the role of inflammation in the presentation of illness and disease. One of these studies, authored by Charles L. Raison and Andrew H. Miller (of the Mind-Body Program at Emory University School of Medicine), looked closely at the relationship between Major Depressive Disorder (MDD) and the immune system. The evidence varied depending on the degree of vulnerability to any interconnected physiologic systems implicated in the etiology of MDD. Levels of inflammatory markers in the depressed individuals were nowhere near the levels seen in autoimmune diseases characterized by significant systemic inflammation (including Rheumatoid Arthritus, Hoshimotos, and Lupus). However, the goal of this thought experiment was to amplify that these small increases are reliably consistent among individuals with MDD. Even though these subtle increases would not flag a Rheumatologist or a Psychiatrist to suspect a diagnostic correlation between the two, dismissing these small physiologic differences would over time vail the significance of other modern diseases that are also characterized by mildly increased inflammatory activity. You may have heard of a few of them; including cardiovascular disease, stroke, cancer, diabetes, and dementia. The study concluded that the minor increases of inflammation observed in individuals with MDD are enough to strongly predict the future development of other modern chronic diseases.
An Alternative Perspective Of Depression
The involvement of inflammation and immune system activity in Major Depressive Disorder is undergoing more research to understand the function of depression from new perspectives. The original question still stands: Why do some individuals experience depression while others do not? Why is depression continuing to genetically manifest in new generations, and at higher rates? Two major theories offer possible explanations for the continued prevelance of depression .