Download An Evolutionary Explanation of Emotion

An Evolutionary
Explanation of Emotion
By Mr Daniel Hansson
Questions
1.
2.
3.
4.
If you had three cows, but only enough to
keep two of them alive, which one would
you slaughter?
Why don’t we marry our sisters or
brothers?
Why are apples sweet? Why do you think
children like sweets?
Consider the following quote. What does it
mean? “We have stone age genes and
minds forced to live in a space age
culture.”
Darwin
•
•
Went on a roundthe-world journey
with “The beagle”
1831
Author of Origin of
species (1859) and
Descent of Man
(1871)
Influence of Darwin
•
•
On Galapagos,
Darwin noticed that
the beaks of finches
differed depending
on the islands
The beaks were
highly adapted to
the food source on
the island
Darwin’s Theory of
Evolution
1. Evolution: Life on earth has evolved
(developed gradually) over millions of years
from a few common ancestors
2. Heredity: Offspring inherits the traits of
their parents
3. Natural selection: Competition of
resources must inevitably arise between
organisms. Traits which enhance adaptation
and thereby survival and reproduction rates,
are the most likely to be transmitted over
generations.
Darwin’s Theory of
Evolution
4. Speciation: Development of different
species occurs because the more adaptive
species in an environment overcomes
competitors.
5. Variation: Even if more adaptive traits are
most common, there is a variation of traits
in a population of a species. This enables
the species to adapt to sudden
environmental changes.
Fitness
An organism’s ability to survive
depends on how well its characteristics
allow it to:
• Exploit the opportunities available in its
environment
• Avoid or deal with the threats presented
by its environment
•
We call this the organism’s fitness
www.psychlotron.org.uk
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Fitness
www.psychlotron.org.uk
Fitness
Yummy!
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Fitness
Arse.
Fitness
Fit organisms are more likely to
survive into adulthood than unfit ones.
• Consequently, they are more likely to
mate and have offspring
• They pass on their genes to the next
generation
•
Gradually, the genes for successful
characteristics spread through the
population
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•
Fitness
Fitness is all about how well an
organism is adapted to its
environment
• The environment changes over time –
sometimes gradually, sometimes rapidly
• So a characteristic/gene that is adaptive
at one time may become maladaptive if
the environment changes
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•
Challenging Evolution
1.
2.
If the purpose of all life is to
reproduce, why aren’t there more
men donating sperm?
If traits that enhance reproduction
are more likely to survive, why is
there homosexuality?
Answers by Evolutionary
Psychologists
1.
2.
The genetic drive to reproduce is an
unconscious urge that nature
expresses by fixed behavioural
patterns, e.g. sexuality.
Homosexual individuals can still have
children. The gene related to
homosexuality may increase fertility
in women.
An Evolutionary
Explanation of Emotion
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•
Motivates behaviour (e.g. to avoid
danger)
Aids communication within a group
Supporting Study 1
•
•
•
Ekman (1973) interviewed and tested
participants from 22 countries, including the
South Fore people in Papua Guinea, who
have had no prior contact to western culture
People with different cultural background
chose the same facial expression for their
emotions
The conclusion is that our basic emotional
life may be innate and has been formed by
natural selection
Supporting Study 2: Fear
•
•
•
•
Disposes us to avoid what may harm us
Arouses the body, make it more apt to flee
the threat
Freezing may help concealment from a
predator
By submission you can avoid aggression
from a stronger opponent
Empirical Support:
Disposition for Fear
•
•
•
Buss (1999): Even though electricity and
cars are more dangerous to us, we are
more likely to fear snakes, heights, confided
spaces, strangers and unfamiliar settings
Mineka (1987): It is easier for infant
Rhesus monkeys to learn to fear toy snakes
than to learn to fear flowers
Mineka (1989): Participants are more
likely to associate pain with snakes and
spiders than flowers or mushrooms
(problem: spiders have never posed a major
threat to humans)
Evolution of phobias
Evolution of phobias
X
Evolution of phobias
X
Evolution of phobias
X
Evolution of phobias
X
Evolution of phobias
X
Evolution of phobias
X
X
X
X
Disgust
•
Disgust helps us to
avoid bad food in
order to minimize
disease and
infection
Empirical support: Innate
Disgust
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Fessler (2006): Women in the first
trimester of their pregnancy are more
sensitive to disgusting scenarios
involving food
Curtis (2004): Disgust reactions are
most strongly elicited for those which
threaten one’s immune system and
decreases with age
Sadness
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•
Sadness triggered
by failure or loss
may discourage the
behaviour that led
to them
To signal need and
to elicit help from
others (Cutili et al.,
2010)
Evaluation of theory:
Strengths
•
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Can provide insights into our
psychology
Empirical support
Universality: Similar behaviors have
been observed across cultures (e.g.
Ekman 1973)
Evaluation: Limitations
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Animal studies: Problems with
generalising to humans
Use of correlation studies: Cannot
infer cause-effect
Because little is known of early
humans, statements of how humans
used to be is hypothetical
Evaluation of theory:
Limitations
•
Underestimation of cognitive and socio
cultural influences on behavior (e.g.
cultural and gender schemas, social
learning)
•
Not all biological traits are adaptations
– some are just side-effects or byproducts of adaptations (Gould, e.g.
writing ability)