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Module 4Behavior, psychological profile, health and survival
What it means to study health from an evolutionary perspective
Survival (and health sciences) in evolutionary context:
• Evolutionary (health) psychology of survival
• Evolutionary psychiatry and psychiatric disorders
• Evolutionary medicine and human disease
Some key concepts:
• An individual’s biological fitness has to do with two components: survival and reproduction
• The ability of an individual to survive in the face of so many life-threatening difficulties and threats,
as well as unforeseen contingencies that jeopardize her welfare and physical health has to do with
her capacity to
-> maintain bodily functions in good shape and repair errors and damage that arise from cells and
organs activity
-> “eat and avoid being eaten”. More generally, an organism’s successful survival depends on a whole suit
of adaptations to find and consume food (i.e., other organisms, if they are heterotrophs) and to avoid
becoming someone else’s food
• Many of these adaptations for survival are actually behavioural and psychological in kind
• Recently, evolutionary theory has been used to address questions related to behavioural and
psychological adaptations for survival and against disease. Some of these approaches have been
elaborated and given the names of new scientific disciplines, including Evolutionary Psychology,
Evolutionary Psychiatry, and Darwinian or Evolutionary Medicine
,Defining health and disease
Health and disease in evolutionary context:
Naturalism: Health is determined by the statistically typical contribution an organ or mental system
makes to an organism's biological fitness, while disease is seen as an impairment of normal functional
ability.
Normativism: suggests that health and disease are based on societal values, with desirable states labeled
as 'healthy' and undesirable states as 'diseased.'
Wakefield's hybrid dysfunction: combines natural function and societal values, defining disorder as a
harmful dysfunction. Dysfunction, in this context, refers to the failure of an internal mechanism to
perform its naturally selected functions, and harm is broadly construed to include negative conditions
according to social values. This approach considers both the evolutionary perspective and societal norms
in defining mental disorders.
Defects versus defenses, the evolutionary perspective
Physical defect versus defence:
• Symptoms need to be mitigated: In the case of physical defects or diseases, the symptoms often
indicate a malfunction or threat to the body. In an evolutionary context, these symptoms need to be
addressed or mitigated to ensure the individual's survival and well-being
• Symptoms need to be “listened to” (smoke detector principle): This refers to the idea that
symptoms, much like a smoke detector signaling a potential fire, should be paid attention to.
Symptoms may serve as signals of underlying issues, and addressing them is crucial for the body's
defense mechanisms.
Psychological (psychiatric) disorders versus adaptations:
• Symptoms need to be treated/mitigated: Similarly, in the realm of psychological or psychiatric
disorders, negative emotions such as anxiety, sadness, or depression may be considered as
symptoms. Evolutionarily, these emotions might have adaptive functions, but in a modern context,
they can become problematic. Treating or mitigating these symptoms is essential for mental health.
• Symptoms need to be “listened to” (smoke detector principle): The "smoke detector principle" applies
to psychological symptoms as well. Negative emotions may indicate a mismatch between the current
environment and the evolved mechanisms for dealing with stress or threats. Listening to these
emotions involves understanding and addressing the underlying issues.
-> Negative emotions (anxiety, sadness, depression), probability and vulnerability: In an evolutionary
context, negative emotions could be responses to situations that pose a threat to an individual's survival
or reproductive success. For example, anxiety might be linked to heightened awareness of potential
dangers, and sadness or depression could be responses to adverse circumstances.
,The evolutionary perspective provides insights to how our biological systems are shaped by evolution
• Mismatch: Our bodies are unprepared to cope with modern environments:
Evolutionary processes have shaped human bodies to thrive in specific environmental conditions that
existed during the majority of our evolutionary history. However, rapid changes in lifestyle, diet, and
environmental factors in modern times can create a mismatch between our evolved biology and
contemporary conditions. This mismatch may contribute to health issues as our bodies may not be
optimally adapted to deal with aspects of modern life, such as sedentary behavior or high-calorie diets.
• Infection: Bacteria and viruses evolve faster than we do:
Pathogenic microorganisms like bacteria and viruses evolve rapidly, allowing them to adapt to changes
in our immune responses. While our immune system has evolved sophisticated defense mechanisms, the
fast-paced evolution of pathogens can sometimes outpace our ability to develop effective immune
responses. This ongoing evolutionary "arms race" between our immune system and pathogens can result
in the occasional emergence of infectious diseases.
• Constraints: There are things that natural selection just can’t do:
Natural selection operates on existing genetic variation and is constrained by the available genetic
material. Some traits or adaptations may be limited by these constraints, preventing the evolution of
perfect solutions to certain challenges. As a result, our bodies may exhibit suboptimal responses or
vulnerabilities to specific conditions.
• Trade-offs: Everything in the body has advantages and disadvantages:
Evolution involves trade-offs, where adaptations that confer advantages in one aspect may have
disadvantages in another. For example, the immune system's inflammatory response, while essential for
fighting infections, can also contribute to chronic inflammatory conditions when not properly
regulated.
• Reproduction: Natural selection maximizes reproduction, not health:
From an evolutionary standpoint, the primary goal is reproductive success, as individuals pass their
genes to the next generation. While good health often contributes to reproductive success, there may be
instances where reproductive success comes at the expense of individual health. Evolutiontion may
favor traits that enhance fertility and survival to reproductive age, even if they have negative
consequences later on
• Defensive responses:
Responses like pain and anxiety are useful in the face of threats: Evolution has endowed us with
defensive responses, such as pain and anxiety, that are beneficial in responding to immediate threats.
Pain alerts us to potential harm, while anxiety can prompt behaviors that enhance survival. However, in
modern environments where chronic stressors are prevalent, these defensive responses, if
overactivated, can contribute to health issues, emphasizing the importance of balancing acute defensive
responses with long-term health considerations.
, The statement emphasizes the functional aspects of anxiety symptoms from a cognitive perspective and
addresses the difficulty in defining 'excessive' anxiety in conditions like Generalized Anxiety Disorder (GAD),
following the DSM-IV criteria. While anxiety symptoms are viewed as functional adaptations, they become
challenging to precisely define when they become excessive. The persistence of anxiety and its link to a
low threshold for threat detection contribute to characterizing GAD symptoms as 'excessive.'"
It has been argued that the intensity or severity of an emotional response alone should not be considered
as evidence of psychopathology (mental disorder). It argues that strong emotional reactions, even if they
are highly aversive, can be adaptive and beneficial in certain situations.
The example given is the severe physical pain experienced in response to a severe physical injury. Despite
being distressing and disabling, this intense pain serves a functional purpose as it signals the body to
address and attend to the injury, facilitating recovery.
The argument extends this idea to mental health, particularly in the context of Major Depressive Disorder
(MDD). It suggests that events such as the loss of a mate, which can be a significant threat to an
individual's reproductive fitness (an evolutionary perspective), may trigger a severe yet functional negative
emotional response. In this case, a strong emotional reaction, like deep sadness or grief in response to
divorce, is viewed as unsurprising and even making functional sense, given the potential impact on
reproductive fitness.
Essentially, the statement challenges the notion that the severity of emotional responses should be
automatically categorized as pathological, emphasizing the adaptive and functional aspects of intense
emotions in certain contexts.
Defects versus defence, the integrated perspective
Behavioural biologists divide
explanatory questions into 2 broad
categories: those concerning ultimate
evolutionary function and those
concerning proximate mechanisms.
The ultimate function of a structure
refers to the reasons that the structure
in its current form has been retained
through evolutionary time, against the
many alternative forms of the same
structure that are thrown up each
generation through genetic mutation
and recombination. Mechanistic
questions concern how a structure
works.
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