Evolutionary Explanations of
Human Behaviour
Objectives
• Assess prior knowledge
• Define Evolution
• Define Evolutionary Psychology
What is Evolutionary Psychology?
Read the article on
page 3 of your
resource pack.
Pick out 5 key points
from the article and
write them on a
post-it!
Natural
Selection
Darwin
Evolution
Appear
Genetic
Adaptive
Mastery Test
How much do you already know?
Complete the multi-choice test on page 2
on paper
Work on your own in SILENCE!!!
Go!
2min
STOP
Marking the Test
• Swap papers!
• Mark the answers as
I read them out
• How did you do?
• You will complete
this again at the end
of the topic – aim to
improve!
Extension Tasks
• Complete the
definitions and the
picture of the model
on page 1 of your
workbook
• Create a poster
about the four parts
of Modern
Darwinism
Evolutionary Explanations of
Human Behaviour
Parental
Investment
Sexual
Selection
Human
Reproductive
Behaviour
Objectives
•
•
•
•
•
State the nature of sexual selection
Evaluate the nature of sexual selection
State the forms of sexual selection
Evaluate the forms of sexual selection
State the consequences of sexual
selection
• Evaluate the consequences of sexual
selection
My ideal partner!
•
•
•
•
•
•
•
Take a piece of plain paper.
Draw the head of a person.
Fold it over and pass left.
Draw the body and arms of a person
Fold it over and pass it left
Draw the legs and feet of a person
Fold it over and pass it left
Key Definition!
• EEA (Environment of Evolutionary
Adaptation)
• This is the environment to which a
species is adapted and the set of
selection pressures that operated at
this time.
• Generally regarded as the time when
our ancestors were hunter-gatherers on
the African savannah.
Nature of sexual selection –
Gender Specific
• Characteristics to promote
reproductive success
• Men – young healthy females
• Women – resource investment
• Female – more choosy (intersexual
competition)
• Male – compete with each other
(intrasexual competition)
Evaluation
•
•
•
•
Buss (1989) study of 37 cultures.
Men – choose on fecundity
Women – choose on resource potential
Scheib (1994) – sperm donor choice
study supported Buss’ findings
Evaluation
• Bereczkei (1997) – females advertised
for family-orientated men
• Female financial independence
• Homosexual relationships – no
reproductive potential.
• Dunbar (1995a) Homosexual adverts
also advertise resources – despite
having no reproductive potential
Nature of Sexual Selection
Origins of Mate Preferences
• Preference for one mate over another
• Links to problem of appropriate mate
choice in EEA
• Mating biased in favour of individuals
with certain characteristics
• Genetic quality of mate determines
genetic quality of offspring!
Evaluation
• Human behaviour influenced by selective
pressure in EEA is not universally
accepted.
• Continuing evolution
• Why so affected by one environment
and not another?
Forms of sexual selection –
Selection for Indicators
• Indicators reveal traits that can be
passed on.
• Show information about mate survival
• Tend to be condition dependent –
healthier = bigger – or revealing – make
better use of indicators, e.g. better
groomed
• Pre-programming
Evaluation
• Indicators can be faked! E.g. female lips
• Handicaps only reliable indicator (Zahavi
1975)
• Facial symmetry.
Forms of sexual selection
Selection for sperm competition
• Sperm is stored
• Size matters!
• Male humans have medium-sized
testicles by primate standards.
• Ancestral males mildly competitive –
females must have had multiple partners
(Baker & Bellis 1995)
Evaluation
• Humans are by nature more promiscuous
than monogamous
• 9% misattributed fatherhood (Baker &
Bellis)
• Majority of people do know who their
father is
• Majority not adulterous
Competition Activity
• Complete the human
intra-sexual
competition activity.
• Be prepared to
share your opinions
Consequences of sexual selection
Physical Characteristics
• Dimorphism (physical
differences between
the sexes) is linked to
female mate choice
Martin et al. (1994)
• Size difference =
polygynous mating
system (one male, many
females)
• More sexual competition
between males.
Consequences of sexual selection
Physical Characteristics
• Facial Characteristics
• Neotenous (child-like) more attractive
(Perrett et al 1994)
• Strong testosterone linked features
• Facial symmetry (Thornhill & Gangstad
1993)
Sexual selection & Human mental
evolution
• Physical and mental
• Neophilia (love of novelty)
• Favour the creative (Miller 1998)
Extension Task
• Complete the task on
Fisher’s hypothesis.
Evolutionary Explanations of
Human Behaviour
Parental
Investment
Sexual
Selection
Human
Reproductive
Behaviour
Objectives
• State & evaluate parental investment
theory
• Compare and contrast the differences
between maternal and paternal
investment and evaluate these
Fisher’s Hypothesis
• What did we find
out?
Key Definition
• Parental Investment – any investment
by a parent in one of his or her
offspring that increases the chance
that the offspring will survive at the
expense of the parent’s ability to invest
in any other offspring (alive or yet to be
born) (Trivers 1972)
Parental Investment Theory
• Trivers (1972)
• Males and females do not invest equally
• Gametes
Evaluation
• Plausible explanation (Buss 1998)
• Men gain from polygyny. Females from
monogamy.
• Polygyny common prior to Western
influence. (Smith 1984)
• Reproduction rates are low among
wealthy people.
• Contraception
• Socially enforced monogamy
Maternal vs. Paternal
Egg
Pregnancy
Childbirth
Feeding
Care
Sperm
-
Symons (1979)
Daly & Wilson (1978)
Evaluation
• Females want male providers because of
infant dependency
• Female want good quality offspring.
• Mistaken paternity supports this.
Cuckoldry
• Self-protection against cuckoldry
• Considerable investment = need for
fidelity (Miller 1998)
• Care not misdirected
Paternal love
• Read the article on
paternal love in the
resource pack
• Pick out 5 key points
and transfer to
post-it notes
• Be prepared to
share
Sexual Jealousy
• Different adaptive problems for males
and females
• Males – incorrect investment
• Females – diversion of resources
• Sexual jealousy a solution (Buss 1995)
• Men – jealous of sexual act
• Women – jealous of shift in emotional
focus
Evaluation
• Buss et al. (1992) male concerned with
sexual fidelity, female concerned with
emotional fidelity.
• Galvanic skin responses
• Veil
• Changes in sexual morals
• Surplus of men means marital life is
more stable (Hill & Hurtado 1996)
Evaluation
• Dunbar (1995b) Joint parental
investment is desirable because of high
cost of successful reproduction.
• Males restrict reproductive activity and
invest more in each offspring.
• Greater male selectivity means female
attractiveness is important compared to
non-human animals.
Sexual Jealousy
• Complete the activity on sexual jealousy
in the activity pack.
• Be prepared to share your answers
Extension Activity
• Complete the
activity on polygyny
and polyandry
• Ensure it is complete
by next lesson.
Evolutionary Explanations of
Human Behaviour
Parental
Investment
Sexual
Selection
Human
Reproductive
Behaviour
Objectives
• State the main ideas about parentoffspring conflict
• Evaluate the main ideas about parentoffspring conflict
Polygyny & Polyandry
• What did we find
out?
Parent-offspring conflict
• Trivers (1994)
• Parents will be in conflict about weaning,
parents will want to wean earlier than
the child
• Parents will encourage children to value
siblings more than they are naturally
inclined to
• Parents will punish conflict and reward
co-operation.
Sibling Rivalry
•
•
•
•
Individual offspring
Fair share
Maximise fitness
Sibling rivalry for
attention and
resources
Evaluation
• Lalumiere et al. (1996) Different
developmental paths
• Harris (1999) Peer socialisation
Age related
parent-offspring conflict
• Begins at conception
(Buss 1999)
• Pre-eclampsia
• Sibling investment
• Transfer of
investment
Evaluation
• High blood pressure
beneficial (Xiong
2000)
• Alliances against
non-kin
• Learned negotiation
skills (Shaffer 1993)
– a non-evolutionary
explanation
Parent-offspring conflict activity
• Read the article on parent-offspring
conflict
• Pick out 5 key points ready to share....
Extension Activity
• Complete the cut ‘n’
stick for the first
section of the topic
• Ensure it is complete
by next lesson
Evolutionary Explanations of
Human Behaviour
Parental
Investment
Sexual
Selection
Human
Reproductive
Behaviour
Objectives
• Review what we have
learned so far
• Construct an answer
to an essay that
meets/exceeds
ALIS target
Mastery Test
How much do you now know!?
Complete the multi-choice test on page 2
on paper
Work on your own in SILENCE!!!
Go!
2min
STOP
Marking the Test
• Swap papers!
• Mark the answers as
I read them out
• How did you do?
• Did you improve?
AO1 & AO2
• Lets look at what makes effective A01
and AO2
• Lets review some essay plans
Writing an Essay
• Choose one of the
essay titles
• Try to choose
whichever you think
is most challenging
to you.
• Review the section
of work
• Write for 30 mins
Reviewing our Essays
•
•
•
•
•
Swap with someone near to you
Read their work
Write one thing that is good
Write one thing they could improve on
Give a mark and explain why you have
given this
Objectives
• Review what we have
learned so far
• Construct an answer
to an essay that
meets/exceeds
ALIS target
Evolutionary Explanations of
Human Behaviour
Unipolar
Disorder
Depression
Bipolar
Disorder
Mental
Disorders
Phobias
OCD
Anxiety
Objectives
• State the symptoms of depression
• State the differences between unipolar
and bipolar disorder
• State the evolutionary explanations of
unipolar disorder
• Evaluate the evolutionary explanations
of unipolar disorder
Mastery Test
How much do you already know?
Complete the multi-choice test on page 2
on paper
Work on your own in SILENCE!!!
Go!
2min
STOP
Marking the Test
• Swap papers!
• Mark the answers as
I read them out
• How did you do?
• You will complete
this again at the end
of the topic – aim to
improve!
Depression is:
• Using mini-whiteboards in groups of 3:
• Create a mind map of symptoms of
depression.
• You have 5 minutes!
• Be ready to share your answers!
Unipolar and Bipolar Disorder
• Unipolar
• Bipolar
• Consists of
depressive phase
only
• Consists of manic
and depressive
phases and shift
between the two
Evolutionary
Explanations of
Depression
Unipolar
Disorder
Social
Competition
Hypothesis
Bipolar
Disorder
Defection
Hypothesis
Reproductive
Fitness
EOBD
Hypothesis
Social Competition Hypothesis
• Price et al (1994)
• Depression is an evolved response to
loss of status
• An adaptive response to losing rank and
seeing self as a ‘loser’
• Prevents risk of further injury
• Preserves relative stability of social
group
• Prevents further competition
Evaluation of social competition
hypothesis
• Difficult to test
• Gilbert & Allan (1998) found feelings of
defeat were significantly correlated
with depression
• Rank Theory (Price & Sioman 1987)
• Yielding subroutine
• Winning subroutine
Evolutionary
Explanations of
Depression
Unipolar
Disorder
Social
Competition
Hypothesis
Bipolar
Disorder
Defection
Hypothesis
Reproductive
Fitness
EOBD
Hypothesis
The defection hypothesis
• Hagen (1999)
• Post-natal depression an adaptive response –
led women to limit investment in the child as
this would reduce overall reproductive
success.
• Hagen (2002)
• Can be generalised to all forms of depression
because it is a response to an event that has
an evolutionary significant cost
Evaluation of defection
hypothesis
• Considerable empirical support
• Lack of social support predicts this
(Gotlib et al. 1991)
• Poor environment predicts this (Warner
et al. 1996)
• Post-natal depression results in loss of
interest in child (Beck 1992)
• Post-natal depression leads to increased
paternal investment (Hagen 2002)
Extension Task
• Complete the case
study 1 activity on
your whiteboard.
Case Study 1
• Lets share our
answers!
Homework
• Log onto
www.ashlawnpsych.wordpress.com
• Follow the instructions under the post
Year 13 Evolutionary Homework due 9th
October
Objectives
• State the symptoms of depression
• State the differences between unipolar
and bipolar disorder
• State the evolutionary explanations of
unipolar disorder
• Evaluate the evolutionary explanations
of unipolar disorder
Evolutionary
Explanations of
Depression
Unipolar
Disorder
Social
Competition
Hypothesis
Bipolar
Disorder
Defection
Hypothesis
Reproductive
Fitness
EOBD
Hypothesis
Objectives
• State the symptoms of depression
• State the differences between unipolar
and bipolar disorder
• State the evolutionary explanations of
bipolar disorder
• Evaluate the evolutionary explanations
of bipolar disorder
Homework
• Log onto
www.ashlawnpsych.wordpress.com
• Follow the instructions under the post
Year 13 Evolutionary Homework due 9th
October
Reproductive fitness
• Beneficial genes are passed on
• Possession of bipolar genes an
advantage
• Small doses v large doses – normal
distribution curve
Evaluation
• Based on assumptions – caused by
multiple genes and the genes are linked
to desirable behaviour
• Lack of genetic evidence – chromosome
22 (Kelsoe et al. 2001)
• Twin studies – high concordance (Nesse
1999)
• Number of genes involved
• Expression of gene may be modified
Evolutionary
Explanations of
Depression
Unipolar
Disorder
Social
Competition
Hypothesis
Bipolar
Disorder
Defection
Hypothesis
Reproductive
Fitness
EOBD
Hypothesis
EOBD Hypothesis
• Sherman (2001) ‘bipolar behaviours are
adaptations to the selective pressures
of long severe winters and short
summers.’
Evidence for EOBD:
• Cold-adapted physique:
• Bipolar linked to thick compact physique
• Large trunk, small extremities
• Improved clothing and shelter made this
adaptation unnecessary
• (Kretschmer 1970)
Evidence for EOBD
• Hibernation:
• Bipolar evolved in response to environmental
adversity
• Depressive phase resembles hibernating
behaviour
• For example – overeating then lethargy and
depression similar to animals gorging and then
sleeping. (Sherman 2001)
Evidence for EOBD
• Adaptive significance in social groups
• Inactivity in winter preserves harmony
and survival
• High energy requirement
• Mania link to challenge, survival and
emergencies
• Aiello & Wheeler
• (1995)
Evaluation of EOBD
• Previc (2002) Hypothesis is unproven
• Makes intuitive sense
• Tries to explain original development
not cause
• Arbisi et al. (1994)
• Neurophysical support – dopamine
fluctuates seasonally
Case study 2
• Read case study 2
• Complete the
questions on paper
• Be ready to share
your answers!
Extension Task
• Complete the
comparison flow
chart between
unipolar and bipolar
disorder
Flowcharts
• Lets share our
answers!
Objectives
• State the symptoms of depression
• State the differences between unipolar
and bipolar disorder
• State the evolutionary explanations of
bipolar disorder
• Evaluate the evolutionary explanations
of bipolar disorder
Unipolar
Disorder
Depression
Bipolar
Disorder
Mental
Disorders
Phobias
OCD
Anxiety
Objectives
• State the symptoms of anxiety
• State some types of anxiety disorders
Anxiety is:
• Using big paper and pens in groups of 3:
• Create a mind map of symptoms of
anxiety.
• You have 5 minutes!
• Be ready to share your answers!
Anxiety
• Anxiety can be defined as feelings of
apprehensiveness or dread in response
to threats that are real or imagined
Symptoms of anxiety
• Fight/Flight/Freeze
The nature of anxiety
• General vs. Specific (Janzen 1981)
• General threat = general response
• Specific threat = Specific response
Anxiety as protection
• Four responses:
(Marks 1987)
• Escape or avoidance
• Aggressive defence
• Freezing/immobility
• Submission or
Appeasement
Types of anxiety disorder
• Phobias
• OCD
• PTSD
• You could be asked to explain two of
these from an evolutionary perspective
Subtypes
• Subtypes of anxiety have evolved to
defend against threat.
• Fear – linked to survival but excessive
fear can cause problems such as phobias
and OCD
Threat situations and fear
response (Mark & Nesse 1994)
• Heights – Induce freezing so unlikely to fall,
excess – fear of small heights e.g. stairs
• Public places – guards against danger away
from home territory, excess – agoraphobia
• Post-traumatic fear – Avoidance of repeated
trauma, excess – PTSD
• Social threats – minimize threat of group
rejection, excess – dysmorphophobia & OCD
Obsessive-Compulsive Behaviour
• Exaggeration of mechanisms that drive
adaptive behaviour
• Grooming behaviour – reduces
parasitism in mammals -> excess washing
• Concern for others – ensures group
stability -> fear of harming others
• Hoarding – guards against shortages ->
hoarding of all things
Is anxiety adaptive?
• Without it you would die! (Tyrell &
Baxter 1981)
• Adrenal gland removal = death
• Pleasurable fear – films, roller-coasters
• Learning
• Why might anxiety be maladaptive?
Are anxiety disorders
inherited?
• Kendler et al. (2000) 3000 twin studies
– common genetic factor in all phobias
and unique genetic factor for specific
ones.
• Nestadt et al. (2000) People with a
first-degree relative with OCD 5x more
likely to have OCD in their lives than
those without.
Anxiety
Adaptive
Maladaptive
Extension Task 1
• Read the anxiety
article in the
resource pack
• Pick out five key
points
Extension Task 2
• Find an example
of a story about
fear in the media
and bring to next
lesson
• Make a list of
treatments for
anxiety disorders
and the main
components (at
least 3)
Objectives
• State the symptoms of anxiety
• State some types of anxiety disorders
Unipolar
Disorder
Depression
Bipolar
Disorder
Mental
Disorders
Phobias
OCD
Anxiety
Objectives
• State types of anxiety disorder
• State and evaluate Pre-potency
• State and evaluate Preparedness
Phobias Extension Task
• What were your key points?
Evolution of Anxiety Disorders
• Ancient fears
• Snakes, heights, storms, darkness, strangers,
seperation
• Phobias – exaggeration of these fears
• Other stimuli eg, leaves no threat = no phobia
• Modern dangers eg cars rarely form phobias
because these have not been around long
enough to have influenced adaptive selection.
Pre-potency
• Evolved to respond to potential threat (little
point in experiencing anxiety after a loss!)
• Ancestors able to respond to threats more
likely to survive and more likely to pass on
genes.
• Natural selection shaped nervous system to
respond to cues
• E.g. noise and visual stimuli of a snake-like
object may cause big anxiety response
• This is PRE-POTENCY – where something has
power to direct experience.
Evaluation of
Pre-potency
• Ohman & Soars
(1994)
• Masked pictures –
bigger anxiety
response than
neutral pictures
Evaluation of
Pre-potency
• Bennet-Levy & Marteau (1984)
• Form and texture different to human =
greatest fear.
• 1 exception – slugs!
Preparedness
• Learning rather than fixed response
• Seligman (1970) – learn an association
between stimuli and fear, once learned,
difficult to extinguish, passed on
genetically.
• Fear in infants gauged by mother’s
reaction. (Marks 1987)
Evaluation
• Strangeness is the problem not the
stimulus itself.
• Prepared to fear the strange – learn not
to.
• Explains high rate of phobias in
childhood and adolescence and reduction
in adulthood.
Evaluation
• We learn some fears readily and these
are difficult to unlearn. McNally (1987)
• Expectancy bias – fear relevant stimulus
(danger, unpleasantness) produces
future responses. No need to invoke
evolutionary history.
• Modern phobias unexplained (eg.
Hypodermic needles)
Nausea and Alcohol
• Garcia & Koelling
(1966) rats &
saccharin
• Berstein (1978) Icecream &
Chemotherapy
• Why do people
persist in drinking
alcohol when it
makes them feel
sick?
Little Albert
• Complete the
activity on Little
Albert from your
resource pack
• Be ready to share
your answers!
Extension Task 1
• Complete the
Evolutionary
explanations of
mental disorders
task.
Extension Task 2
• Mind map an essay title for depression
and for anxiety
• Choose the one you are then least
comfortable with and write it!
Objectives
• State types of anxiety disorder
• State and evaluate Pre-potency
• State and evaluate Preparedness
Evolutionary Explanations of
Human Behaviour
Unipolar
Disorder
Depression
Bipolar
Disorder
Mental
Disorders
Phobias
OCD
Anxiety
Objectives
• Review what we have
learned so far
• Construct an answer
to an essay that
meets/exceeds
ALIS target
Mastery Test
How much do you now know!?
Complete the multi-choice test on page 2
on paper
Work on your own in SILENCE!!!
Go!
2min
STOP
Marking the Test
• Swap papers!
• Mark the answers as
I read them out
• How did you do?
• Did you improve?
AO1 & AO2
• Lets look at what makes effective A01
and AO2
• Lets review some essay plans
Writing an Essay
• Choose one of the
essay titles
• Try to choose
whichever you think
is most challenging
to you.
• Review the section
of work
• Write for 30 mins
Reviewing our Essays
•
•
•
•
•
Swap with someone near to you
Read their work
Write one thing that is good
Write one thing they could improve on
Give a mark and explain why you have
given this
Objectives
• Review what we have
learned so far
• Construct an answer
to an essay that
meets/exceeds
ALIS target
Evolutionary Explanations of
Human Behaviour
Language
Foraging
Development of
Human Intelligence
Social
Theories
Brain
Size
Objectives
• State and evaluate evolutionary factors
in the development of human
intelligence including:
• Foraging demands
• Social demands
• Language
Mastery Test
How much do you already know?
Complete the multi-choice test on page 2
on paper
Work on your own in SILENCE!!!
Go!
2min
STOP
Marking the Test
• Swap papers!
• Mark the answers as
I read them out
• How did you do?
• You will complete
this again at the end
of the topic – aim to
improve!
Intelligence is:
• Using big paper and pens mind map in
pairs what you think intelligence is
• Include anything you think is associated
with intelligence
• Be ready to share!
Some key definitions:
• Intelligence – the ability to think
flexibly
• Primates – includes lemurs, monkeys and
apes
• Great apes – the most advanced group
of primates including gorillas,
chimpanzees and humans
• Hominids – early humans
Why did intelligence evolve?
•
•
•
•
Survival
Food
Shelter
Mating
Foraging – Finding food
• Dunbar (1992)
• Fruit-eaters had high cognitive demand
• Needed to monitor food supply and
ripening patterns, develop harvesting
plans and survive in the interim
• Leaf-eaters had lower cognitive demand
as food more readily available
• Hominids were fruit eaters
Foraging – tool use
• Mercader et al. (2002)
• Chimps use stones as hammers to crack
open nuts
• Most successful hunter-gatherers also
used tools
• These tribes survived
Evaluation of foraging
• Is tool use a cause or an effect of
intelligence?
• Is tool use developed by trial and error
learning?
• Visalberghi & Trinca (1987) – Monkeys used
trial and error to find suitable tools and
showed no understanding of why one worked
and not another
• Byrne (1995) only chimps use tools in the wild
Social Theories
• Machiavellian Intelligence (Whiten &
Byrne (1998) – Human intelligence may
be an adaptation to social problem
solving. Individuals able to use others
without causing aggression would be
favoured. This deceit seems
cooperative but is actually selfish
Evaluation
• Dunbar (1992)
• Strong positive correlation between
group size and neocortex ratio
• Polygamous primates had a larger
neocortex ratio than monogamous ones –
polygamy involves more complex social
relations
Machiavellian Intelligence
• Forming alliances
• Harcourt (1992)
• Power in social groups = right allies not
physical strength
• Alliances formed based on ability to
provide useful future help
Machiavellian Intelligence
• Manipulation & deception
• Byrne (1995)
• Manipulate others into providing
unwitting help
• Ability to understand and plan deception
• Diversions of attention
Evaluation
• Byrne & Whiten (1992)
• Strong positive correlation between
amount of tactical deception and
neocortex ratio
• Suggests a clear relationship between
social manipulation and intelligence
Evaluation
• Cosmides (1989)
• Variations of the Wason card task
• Particpants solved it 75% of the time if
it is a social context
• Only solved 21% of the time with
unfamiliar context
• Suggests a link between intelligence and
social problems
D F
3
7
If a card has a ‘D’ on one side it
has a ‘3’ on the other side.
Which cards do you need to
turn over to find out if this is
true?
Beer
Coke
25
16
You are a bouncer in a bar.
You must make sure that no under-age drinkers
have beer.
Each card is a customer
It says age on one side and drink on the other
Which cards need turning over?
Meat-sharing Hypothesis
• For ancestors in the EEA meat was an
important source of saturated fat
• Chimpanzees face similar problems
today
• When they do manage to kill they eat
the fattiest parts first not the lean
tender flesh
Meat - sharing
• Meat could be used to form alliances
• Meat could be used to persuade females to
mate
• Stanford (1992) observed:
• Males withheld meat until after sex
• Hunting more prevalent when females were
sexually receptive
• Sexually receptive females had more success
when begging for meat
• Requires individual recognition and scores of
debts, credits and relationships
Evaluation
• Hill & Kaplan (1988)
• Men in Paraguay give women meat for
sex
• Gilby (2001) males share meat with
receptive and non-receptive females
• Mitani and Watts (2001) males share
meat with other males to form alliances
because hunting was more successful in
groups
Language
• Humans are the only species to develop
this spontaneously.
• Other species show precursors –
attributing intentions and beliefs to
others (eg. Sally-Anne test)
• Chimpanzees and gorillas express
thoughts and emotions through sign
language and understand human
communication
Evaluation
• Human language is likely to be the outcome of
rather than the cause of intelligence
• Once language evolved it had a significant
effect on further intelligence development
• Cultural transmission is only possible through
language
• Vygotsky – language transforms elementary
mental functions (possessed by all animals)
into higher mental functions
Human Intelligence
• Read the article on
human intelligence in
the resource pack
• Pick out 5 key points
and write them on
post-it notes.
• Be ready to share!
True or False?
• Complete the activity True/False
questions of intelligence using what we
learned today.
• How will you do?
Extension Activity
• Using Activity 8 on Cosmides and
Tooby’s study, conduct the experiment
and bring your results to next lesson
Objectives
• State and evaluate evolutionary factors
in the development of human
intelligence including:
• Foraging demands
• Social demands
• Language
Evolutionary Explanations of
Human Behaviour
Language
Foraging
Development of
Human Intelligence
Social
Theories
Brain
Size
Objectives
• State and evaluate theories into the
relationship between brain size and
intelligence including:
• Comparative studies
• Human Studies
Cosmides & Tooby
• What were the results of your study?
Brain Facts
• 2% of body mass –
20 % of metabolic
rate
• Large brains would
not have evolved
unless they gave
humans a significant
advantage
• Important in
cognitive
development
Comparative studies
Brain Quantity
• Absolute brain size – Most intelligent
species would be the ones with the
biggest brains = sperm whale
• Big brain = big body
• Need to control and maintain big body
needs a big brain
Brain quantity
•
•
•
•
Brain:body ratio
Jerison (1978)
Encephalization quotient (EQ)
Actual brain mass is divided by
expected species brain size
• High EQ = High intelligence
• Humans = 7 (highest), other primates
2.34, Dolphins = 4.5
Evaluation
• EQ not supported by research
• Macphail (1982) rats and squirrels had
the same performance on a learning task
but rat EQ = 0.40 squirrels EQ = 1.10
• Different species comparison is
difficult.
• Different perceptual systems
Brain Quality
• Holloway (1979)
• Growth of the
neocortex is
responsible for
evolution of
intelligence
• Mammals 6 layers of
neocortex
• Cetaceans (whales,
dolphins) 5 layers.
Evaluation
• Cetacaens are highly intelligent
• Herman (1986) – Dolphins can
understand human language and perform
complex tasks beyond the ability of
chimpanzees.
• Fewer neocortical layers but the same
neural density and size of frontal lobes
as humans
Brain size in Humans
Head size and IQ
• Sir Francis Galton (1888)
• Studied Cambridge undergraduates
• Insignificant relationship between head size
and intelligence
• Wickett et al. (1994) repeated and found
significant relationship
• Broman et al. (1987) Head perimeter at birth
predicted head perimeter at age 7 and head
perimeter at both ages predicted IQ
MRI measures
• A recent development which allows
accurate measurement of brain size
• Andreasen et al. (1993) found
significant relationship
• Tan et al. (1999) used male and female
Turkish students and found a significant
relationship.
Evaluation
• Other meaningless correlations also found, eg.
Amount of cerebrospinal fluid and IQ (Egan
et al. 1994)
• Other causal factors of big brains!
• Diet
• Some aspects of intelligence not measure by
IQ tests so may be normal in terms of IQ.
E.g. expertise is critical to survival and
requires brain capacity but not measured by
IQ tests
• No simple relationship between brain size and
IQ
Brain Structure in humans
Cortical Neurones
• Haug et al. (1987)
• Correlation between
brain size and
number of cortical
neurones
motor end
plates
nerve impulses
axon
muscles fibres
cell body
dendrites
Evaluation
• Relationship between neurones and brain
size is supported by animals reared in
enriched environments have more
neurones
• Diamond (1991) – rats reared in
enriched environments had larger brains
and more neural connections.
• Brain development relies on experience
Grey matter
• Size of the regions of the brain
associated with intelligence is under
tight genetic control
• Thompson et al. (2001) MRI twin study
• Volume of grey matter is highly
heritable and an important determinant
of IQ
Evaluation
• Development of grey matter is affected
by genes and environment
• Young adults have more grey matter
than middle-aged people – likely to be
due to improved diet (Storfer 2001)
Sex differences
• Ankey (1992)
• Brains of men larger than brains of
women in both European-American and
African-American cultures
• Supported by similar studies by Rushton
(1992) & Pakkenberg & Gundersen
(1997)
Evaluation
• Size differences are accurate
• Research cannot account for men and
women obtaining the same IQ scores
(Peters 1993)
• Ankey (1992) different intellectual
abilities
• Female brains may be better organised
(Johnson 1996) as women have larger
corpus callosum.
The intelligence gene
• Read the article in the resource pack
• Pick out 5 key points and write them on
post-it notes
• Be ready to share
That’s all folks!
• That is all the input on Evolutionary
Psychology
• Complete the quiz at the end of your
resource pack using your knowledge of
the whole topic!
Objectives
• State and evaluate theories into the
relationship between brain size and
intelligence including:
• Comparative studies
• Human Studies
Evolutionary Explanations of
Human Behaviour
Language
Foraging
Development of
Human Intelligence
Social
Theories
Brain
Size
Objectives
• Review what we have
learned so far
• Construct an answer
to an essay that
meets/exceeds
ALIS target
Mastery Test
How much do you now know!?
Complete the multi-choice test on page 2
on paper
Work on your own in SILENCE!!!
Go!
2min
STOP
Marking the Test
• Swap papers!
• Mark the answers as
I read them out
• How did you do?
• Did you improve?
AO1 & AO2
• Lets look at what makes effective A01
and AO2
• Lets review some essay plans
Writing an Essay
• Choose one of the
essay titles
• Try to choose
whichever you think
is most challenging
to you.
• Review the section
of work
• Write for 30 mins
Reviewing our Essays
•
•
•
•
•
Swap with someone near to you
Read their work
Write one thing that is good
Write one thing they could improve on
Give a mark and explain why you have
given this
Objectives
• Review what we have
learned so far
• Construct an answer
to an essay that
meets/exceeds
ALIS target