Randy Nesse, expert in mental health and evolutionary psychiatry, discusses why evolution left us vulnerable to depression and anxiety. Topics include the purpose of anxiety, complexity of mood regulation, genetic morphs in fish species, complexity of depression, trade-offs in evolutionary shaping, unconscious motivations, advancements in evolutionary medicine, risk-taking and anxiety, impact of ambitious goals on mental health, and aging from an evolutionary perspective.
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Quick takeaways
Anxiety is a protective response that alerts us to potential threats and can be managed effectively.
Sadness serves the important function of motivating behavior to prevent further losses and adapt to change.
Depression's high prevalence raises questions about its adaptive functions and how modern lifestyle contributes to its development.
Individuals can have varying mood levels due to gene recombination, and the effects of modern life on mental health are still unclear.
Evolutionary thinking in psychiatry challenges simplistic views and provides opportunities for more effective treatments.
Deep dives
Anxiety as a Protective Response
Anxiety is a natural protective response that alerts us to potential threats and helps us take preventive action. It is a useful system that has evolved to ensure our survival by signaling the possibility of losing something important. The threshold for anxiety to activate is set high because the cost of missing a potential threat is much greater than the cost of false alarms. However, individuals who experience excessive or unwarranted anxiety may have a heightened sensitivity in their anxiety response system. This can be a result of various factors, such as past experiences or genetic predispositions. Understanding the evolutionary basis of anxiety helps individuals recognize its protective role and manage it in a more effective way.
The Adaptive Role of Sadness
Sadness, unlike anxiety, is a response to a loss that has already occurred. It may not appear immediately useful, as it cannot change the past. However, sadness serves an important function by motivating behavior that can prevent further losses and initiate adaptive responses. For example, in response to the loss of a loved one, sadness can prompt individuals to seek support from others, take necessary precautions to avoid similar losses in the future, or adapt their behaviors to prevent similar situations. Sadness plays a role in recalibrating our responses and guiding our actions to minimize future losses. Overall, sadness is an emotion that allows us to grieve, reassess our circumstances, and ultimately adapt to prevent future losses.
Depression: A Complex Mental Health Challenge
Depression presents a more complex challenge to understand from an evolutionary perspective. The high prevalence of depression poses questions about why a condition that impairs reproductive fitness would persist in the population. One possible explanation is that depression may have had adaptive functions in the ancestral environment, such as signaling the need to conserve energy during difficult times or deterring risky behaviors. However, with the significant disruptions and pressures of our modern lifestyle, these adaptive responses may become maladaptive and contribute to the development of depression. Depression is a multifaceted phenomenon, influenced by a combination of genetic, environmental, and social factors. Exploring the complex interplay of these factors can provide valuable insights into the origins and management of depression.
Variation in mood and genetic interactions
Individuals can have varying mood levels due to the recombination of genes each generation. The interaction between multiple genes can result in extreme mood swings or a lack thereof. This variation is maintained by natural selection to adapt to different situations. However, some individuals who fall on the extremes may face reproductive challenges. The frequency of severe depression and anxiety has been debated, with some studies suggesting it remains relatively stable over time. The effects of modern life, social structures, diet, exercise, and cultural factors on mental health are still unclear.
The role of mismatch and breakdown in mental and physical health
The constant generation of variation in genes through sexual reproduction can lead to incompatibilities and mutations with potential negative effects. The body's biology is subject to breakdowns as well, due to the challenges of maintaining genetic integrity. Our bodies and minds are not adapted perfectly to the modern world, and this mismatch can contribute to ill health. However, it is important to note that there may not always be specific explanations for individual diseases or disorders, as the complexity of gene-environment interactions and epistasis (gene-gene interactions) make it challenging to pinpoint exact causes.
The impact of natural selection in shaping variation and depression
Natural selection maintains variation in traits, including mood regulation mechanisms. Each individual's genetic makeup and interactions between genes play a role in depression and other mental health conditions. Epistatic interactions may help explain the heritability and variation observed. The effects of modern environments and social structures on mental health are still being researched. Variation in mood and mental health illustrate the ongoing evolutionary process of optimizing cognitive and social abilities, which can lead to challenges but also potential benefits.
Impact of Evolutionary Thinking in Psychiatry
Evolutionary thinking is revolutionizing psychiatry, providing new insights into mental disorders. By understanding how our minds and behaviors were shaped by natural selection, we can better comprehend the origins and vulnerabilities of mental disorders. This perspective challenges the simplistic view that genes or specific brain structures solely cause disorders, emphasizing the importance of evolutionary mechanisms. This approach offers a paradigm shift in understanding mental health and provides opportunities for more effective treatments in the future.
Applying Evolutionary Medicine to Infectious Diseases and Autoimmune Disorders
Evolutionary medicine has made significant strides in understanding and treating infectious diseases and autoimmune disorders. By using evolutionary theory, researchers have developed strategies to combat antibiotic resistance and improve cancer treatments. They have also explored how changes in our environment and reduced exposure to pathogens contribute to the rising prevalence of autoimmune disorders. Applying evolutionary principles to medicine opens up new avenues for understanding the causes and optimizing treatments of various diseases.
The Role of Evolutionary Psychiatry in Understanding Mental Disorders
Evolutionary psychiatry aims to uncover why we are vulnerable to mental disorders by studying the basic science behind our minds. While it is still an ongoing process with much more to discover, this approach highlights the impact of evolution on shaping our mental capacities, character, and reactions to certain stimuli. Specific behaviors and traits may have been advantageous in certain ancestral environments, but evolution may not have had the selection power to program for behaviors that were only beneficial in narrow circumstances. Additionally, genes that influence mental disorders are not limited to protein-coding regions, but are found in so-called 'junk DNA.' Understanding the genetic interactions and variations that make people vulnerable to mental disorders is an important focus for ongoing research, aided by advancements in genomic data analysis.
Risk Taking and Sex Differences: An Evolutionary Perspective
One hypothesis from evolutionary psychology suggests that there should be a difference in levels of risk-taking between the sexes. Research has shown that men tend to engage in riskier behaviors and exhibit higher mortality rates compared to women. This difference in risk-taking behavior may be influenced by various factors, including cultural and biological aspects. However, it is essential to approach such hypotheses with caution, as generalizing sex differences across all individuals and cultures can lead to oversimplification and potential biases. Comprehensive studies are needed to further explore the complexities and variations in risk-taking behavior between sexes and across different contexts.
Mental health problems like depression and anxiety affect enormous numbers of people and severely interfere with their lives. By contrast, we don’t see similar levels of physical ill health in young people. At any point in time, something like 20% of young people are working through anxiety or depression that’s seriously interfering with their lives — but nowhere near 20% of people in their 20s have severe heart disease or cancer or a similar failure in a key organ of the body other than the brain.
From an evolutionary perspective, that’s to be expected, right? If your heart or lungs or legs or skin stop working properly while you’re a teenager, you’re less likely to reproduce, and the genes that cause that malfunction get weeded out of the gene pool.
So why is it that these evolutionary selective pressures seemingly fixed our bodies so that they work pretty smoothly for young people most of the time, but it feels like evolution fell asleep on the job when it comes to the brain? Why did evolution never get around to patching the most basic problems, like social anxiety, panic attacks, debilitating pessimism, or inappropriate mood swings? For that matter, why did evolution go out of its way to give us the capacity for low mood or chronic anxiety or extreme mood swings at all?
Today’s guest, Randy Nesse — a leader in the field of evolutionary psychiatry — wrote the book Good Reasons for Bad Feelings, in which he sets out to try to resolve this paradox.
In the interview, host Rob Wiblin and Randy discuss the key points of the book, as well as:
How the evolutionary psychiatry perspective can help people appreciate that their mental health problems are often the result of a useful and important system.
How evolutionary pressures and dynamics lead to a wide range of different personalities, behaviours, strategies, and tradeoffs.
The missing intellectual foundations of psychiatry, and how an evolutionary lens could revolutionise the field.
How working as both an academic and a practicing psychiatrist shaped Randy’s understanding of treating mental health problems.
The “smoke detector principle” of why we experience so many false alarms along with true threats.
The origins of morality and capacity for genuine love, and why Randy thinks it’s a mistake to try to explain these from a selfish gene perspective.
Evolutionary theories on why we age and die.
And much more.
Producer and editor: Keiran Harris Audio Engineering Lead: Ben Cordell Technical editing: Dominic Armstrong Transcriptions: Katy Moore
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