…all the corporeal and mental organs …have been developed through natural selection, or the survival of the fittest, together with use or habit... 

(Charles Darwin, 1876)

NS = differential survival of traits

Genetic mutations lead to an individual acquiring a propensity that makes him better adapted than his peers in surviving & passing on genes (“fitness”)

Over generations, the attribute will become established as a standard component in the species genome

Food acquisition

Cooperation

Inclusive fitness

Inclusive fitness

Tribal bonding

Reciprocal altruism

Conflict over resources

Self defence

“Adaptations” shaped by Natural Selection

Each emotion is a specialised state that adjusts cognition, physiology, subjective experience & behaviour so that the organism can respond effectively in a particular kind of situation

Positive & negative emotions are derived from the two types of basic arousal

Pleasurable sensations … stimulate the whole system to increased action. 

Hence it has come to pass that most or all sentient beings have been developed in such a manner, through natural selection, that pleasurable sensations serve as their habitual guides. 

But pain or suffering… lessens the power of action, yet is well adapted to make a creature guard itself against any great or sudden evil. 

…if long continued, causes depression

(Darwin Francis (ed.), The Life and Letters of Charles Darwin, 1887)

Our ancestors faced many more kinds of threats than opportunities, as reflected by the fact that twice as many words describe negative as positive emotions!

The emotions were “designed not to promote the happiness & survival of the individual, but to favour maximum transmission of the controlling genes.”

(EO Wilson)

"People, like all other organisms, are not evolved to maximise health, wealth, happiness or any other trait – but to have descendants, which is the continuation of life."  

(Chisholm, 1999)

Focus on physical diseases

Descriptive classifications (Kraeplin, Bleuler, Maudsley)

Psychoanalytic model

Behavioural model

Descriptive non-aetiological classifications (DSM)

Biomedical model: biological reductionism

Essential in allowing researchers to study comparable groups

Widely criticised for:

	Lacking a foundation in theory
	Encouraging simplistic thinking of psychiatric syndromes as discrete diseases  (Kendell, 1984)
	Neglecting maladaptive psychological processes

Most research attempts to explain “what” & “how”

Evolutionary approaches examine “why” we are susceptible by considering the design characteristics

Proximate & Evolutionary explanations are not competitors, but two halves of a whole 

Causal hypotheses

Integration of prevailing models into a framework

A theory of environment-behaviour-gene interactions

A theory of behaviour, motivations & function 

An evolutionary classification?

A non-judgmental, normalising, humanising explanatory model for patients

Natural selection has equipped us with lifespan-specific, context-sensitive archetypal propensities to navigate biosocial imperatives that facilitate inclusive fitness.

Genes are conveyers of potential for species-characteristic behaviours, rather than rigid determinants of social behaviour.

(Stevens & Price, 2000)

Human “instinct” 

(William James, Principles of Psychology, 1890)

“Collective unconscious” 

(CG Jung)

Mother-infant instinct 

(Bowlby, 1958)

(Gardiner, 1988)

(Stevens & Price, 2000)

Harm from strange humans --> Stranger anxiety 

Separation from carer --> Separation anxiety 

Threats to status/group membership --> Social anxiety 

Socially unaccepted impulses --> Obsessive self-doubt

Lack of food or other resources --> Obsessive hoarding

Getting sick --> Hypochondriasis/Obsessive cleanliness

Dangerous small animals --> Small animal phobias 

Potential attack to family members --> General anxiety 

Imminent attack by predator --> Panic

Environment in which attack is likely --> Agoraphobia 

(Adapted from Nesse, 1990)

… to motivate to urgent action

for survival

…to respond to Danger…

…with Fight …

… Or Flight …

(Walter Cannon, 1929)

Anxiety is a useful defence

…but it uses extra calories, makes us less fit for everyday activities & damages tissues

So why is it so readily triggered?

Because the cost of getting killed even once is enormously higher than the cost of responding to 100 false alarms

Loss of attachment – carer, mate (Bowlby, 1969)

Loss of rank – social status (Stevens & Price, 2000)

Loss of resources  (Nesse, 2000)

	Internal  Trauma Bodily damage
	External Bad decisions e.g. wasted effort pursuing risky goals  Disruption to major life goals and enterprises

Communicate (Darwin, 1872) need for help

Signal yielding in hierarchy conflict

Disengage from unreachable goals

Regulate patterns of investment

Social Competition Hypothesis of Depression

	Agonistic behaviour was principal form of social competition underlying sexual selection
	Involuntary subordinate strategy functions to: Inhibit aggression towards rivals Acceptance of outcome through yielding preserves the loser Signal submission: ‘no threat’ to rivals as ‘out of action”

Loss of resource holding potential (self esteem) can cause depression

(Price, Sloman, Gardner, Gilbert, Rohde, BJP, 1994)

Serotonin (5HT) in a-male (highest ranking) vervet monkeys 2x other males

When lost their position: appeared depressed (huddled, rocked, refused food) & dropped 5HT levels

Depressed behaviour prevented by Prozac, which raised 5HT

If removed a-male & gave Prozac to random male, that male became a every time

(Raleigh & McGuire, )

Sociobiology/Behavioural Ecology

Ethological Models

Evo Psych (Cognitive) Models

Psychiatric Models

Neuroscientific models 

Archaeological Models

Anthropological Models Philosophical Models

Blank slate / “Cupboard love” theory  = Behaviour is the result of  classical conditioning

General purpose computer

Learning

Culture

In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation." 

(Darwin: Origin of Species, 1859)

The view of the mind as containing a whole suite of modular psychological adaptations
corresponding to functional components of the CNS solving particular past reproductive problems 

Each blade represents pre-programmed algorithms sensitise the organism to monitor specific situations 

biases to learn certain behavioural responses

(Leda Cosmides & John Tooby, 1997)

Social cognition: information processing that contributes to the correct perception of dispositions & intentions of other individuals

Theory-of-Mind: inferring mental states of others 

(Martin Brune, 2001)

Group cooperation (reciprocal altruism) requires cheater detection algorithms 

(Trivers, 1971)

The Social Brain Hypothesis: Vol. of non-visual neocortex correlates with group size & length of juvenile period 

(Dunbar, 1998)

All perform worse on ToM tasks:

	Autism
	Aspergers
	SCZ (acute episodes) Pathological mind-reading inferences Intentions of others perceived as negatively related to self Pathological egocentrism

Caused by genetic abnormalities, infection, toxins, developmental factors

Result in:

	Malfunction (e.g. SCZ, autism, learning disorders, dementia), or
	Dysregulation of the expression of adaptive responses (e.g. melancholia, BPAD)

What can account for a high incidence of genes that can decrease fitness?

Predisposing genes advantageous in combo with other genes or in certain environments

Other effects that offer slight advantage in most carriers

e.g. mind-reading capacity, protect against a disease (like SCA), suspiciousness, creativity, leadership potential ? group splitting ?

Extreme or pathological combinations of hyperthymic /cyclothymic / irritability personality traits 

Achievement & creativity are evident in bipolar patients b/w acute episodes (Andreasen) & non-ill relatives

Music, performing arts & poetry may have evolved by sexual selection

Leadership traits: face challenges, increase group stability

Risk-taking & exploration

(Akiskal, 2000)

Exposure to novel environmental circumstances or idiosyncratic learning histories 

Normal brain mechanisms

Imperfection of evolved mind programs

Examples: some anxiety & depressive disorders, addictions, fetishes

Mental disorders the result of “frustration of archetypal intent” 

(Stevens, 1982)

Developmental view

Comorbidity due to failure of early biosocial imperative (upstream block) undermining downstream archetypal intents