Lecture 1 Foundations of evolutionary psychology
Learning goals
- Be able to articulate what is evolutionary psychology
- Be able to identify the three essential ingredients of evolution via natural selection
- understand the difference between natural and sexual selection
- Be able to identify why Neanderthals went extinct
- Know the history of evolutionary psychology
- Be able to list procedures for identifying adaptive problems
- Be able to identify common misunderstandings about evolutionary theory and evolutionary
psychology
Why?
Main question is why?
- Why do people do these things?
- Can we explain them with existing theories in psychology?
o Could we gain insights by thinking about humans as a biological species, subject to
the same environmental pressures as other animals?
Evolutionary psychology
- Evolutionary psychology is the study of human behaviour, affect and cognition from an
evolutionary perspective
- Using evolutionary theory to understand why the human mind works this way and how it has
been designed.
- In effect, it means viewing humans as part of the animal kingdom, subject to the same laws
of evolution, natural selection, etc.
o This might seem contentious! (but there is really no plausible alternative)
o every species, including ours, has its own nature
History of evolutionary thinking
- Greek philosophers (600-400 bc)
- Aristoteles (300 bc)
- Medieval Christianity (16th century)
- Lamarck (18th century)
- Darwin (19th century)
- Mendel (19th century)
- DNA discovery and the modern synthesis in biology (20th century):
o 1. Function (evolution)
o 2. Mechanism (gene)
,Jean-Baptiste Lamarck (1744-
1829)
- inheritance of acquired characteristics
- use and disuse of traits
- example: giraffes long neck
o niche: only creature able to reach
the top of the trees
o stretches out neck during lifetime
is given to offspring
Charles Darwin (1809-1882)
- Grandfather pf evolutionary psychology
- did not agree with the Lamarck theory
o what happens during your lifetime does not change your genes/DNA
- should take the evolutionary approach of explaining human behaviour very seriously
- book “on the origin of species” (1859)
o caught and investigated finches
thought: maybe these finches of different islands have different ancestors
developed different beak depending on food present on island
- natural selection and survival of the “fittest”
o Darwin: “as many more individuals of each species are born than can possibly
survive; and as, consequently, there is a frequently recurring struggle for existence, it
follows that any being, if it vary however slightly in any manner profitable to itself,
under the complex and sometimes varying conditions of life, will have a better
chance of surviving, and thus be naturally selected. from the strong principle of
inheritance, any selected variety will tend to propagate its new and modified form.”
Resistance against the evolutionary theory
- People would not and could not believe
o Church still big part in shaping the world
o Darwin was not taken seriously
The tree of life
- DNA-studies reveal that humans share a common ancestor with bacteria, 4 billion years ago
- Build from the same DNA as we are
The primate tree
- based on DNA evidence
o Share DNA with non-human primate
- Share common ancestor: we are not descended from a chimpanzee
A walk through human evolution
- Only modern human left
- At different types different types of humans present
,Natural selection
Components of natural selection
- variation
o individuals are born with slightly different traits
- inheritance
o traits passed on from parent to offspring
- selection
o certain environment calls for certain traits
Natural selection process
- there is individual variation in traits (physical,behavioral)
- Some trait variants allow their bearers to better compete for resources
- if these traits are inheritable then they are passed on from generation to generation
- the result: individuals of a species become better adapted to their environments over time.
Genes
- mechanism for evolution using natural selection
- gregor mendel (1822-1884)
o understood that genes and traits are heritable
o found that different trait varieties are possible
DNA variation
1. mixing parental genes (mendelian genetics)
2. recombination
3. mutation
Sexual selection
Darwin
- Was searching for counterarguments to his theory
o Peacock: carries big tail which makes it an easy target
o However: explainable using sexual selection
- Peacock: carries big tail and makes itself easy prey
Forms of sexual selection
- inter sexual competition:
o traits passed on because they are good at attracting opposite sex mates
- intra sexual competition:
o traits passed on because they are good at winning same sex competitions for mates
- Still debated which is the most important in humans
, Runaway effect
- runaway selection: secondary sexual traits become genetically correlated with a preference
for the trait in the other sex
- can go really fast
Savannah hypothesis
- When or ancestors moved from the trees into the savannah new selection pressure emerged
o Only able to survive by creating groups
o Created changes in physical changes
Bipedalism: able to see more and get around more easily
The human brain: evolutionary history
- Brain function: Information processing organ
o transforms inputs from the environments into functions
- triune brain (maclean, 1960).
o reptilian brain, brain stem (avoid and approach)
ancestral brain: takes care of basic functions
o paleo-mammalian complex, emotions (limbic system)
takes care of primary emotions
o neo-mammalian complex, planning (neo cortex)
associated with higher intellectual functions
planning, makes us quite unique as primates
Increase in brain size over mya
- steady increase
- not linear increase
- does a big brain mean a smart brain
o difficult to determine
o probably not exactly correlated
Probable causes for increase in brain size
- ecology (climate, rainfall)
o physical environment is very challenging
- technology (tools, weapons)
o needed to able to get food by hunting
o able to use hand due to bipedalism
- social factors (need to cooperate)
o caused by social pressure due to living in larger groups
o to protect from predictors
o but more competition for resources
- cultural factors (social learning)
o ability to culturally learn from each other
o need/pressure to culturally learn from each other
Learning goals
- Be able to articulate what is evolutionary psychology
- Be able to identify the three essential ingredients of evolution via natural selection
- understand the difference between natural and sexual selection
- Be able to identify why Neanderthals went extinct
- Know the history of evolutionary psychology
- Be able to list procedures for identifying adaptive problems
- Be able to identify common misunderstandings about evolutionary theory and evolutionary
psychology
Why?
Main question is why?
- Why do people do these things?
- Can we explain them with existing theories in psychology?
o Could we gain insights by thinking about humans as a biological species, subject to
the same environmental pressures as other animals?
Evolutionary psychology
- Evolutionary psychology is the study of human behaviour, affect and cognition from an
evolutionary perspective
- Using evolutionary theory to understand why the human mind works this way and how it has
been designed.
- In effect, it means viewing humans as part of the animal kingdom, subject to the same laws
of evolution, natural selection, etc.
o This might seem contentious! (but there is really no plausible alternative)
o every species, including ours, has its own nature
History of evolutionary thinking
- Greek philosophers (600-400 bc)
- Aristoteles (300 bc)
- Medieval Christianity (16th century)
- Lamarck (18th century)
- Darwin (19th century)
- Mendel (19th century)
- DNA discovery and the modern synthesis in biology (20th century):
o 1. Function (evolution)
o 2. Mechanism (gene)
,Jean-Baptiste Lamarck (1744-
1829)
- inheritance of acquired characteristics
- use and disuse of traits
- example: giraffes long neck
o niche: only creature able to reach
the top of the trees
o stretches out neck during lifetime
is given to offspring
Charles Darwin (1809-1882)
- Grandfather pf evolutionary psychology
- did not agree with the Lamarck theory
o what happens during your lifetime does not change your genes/DNA
- should take the evolutionary approach of explaining human behaviour very seriously
- book “on the origin of species” (1859)
o caught and investigated finches
thought: maybe these finches of different islands have different ancestors
developed different beak depending on food present on island
- natural selection and survival of the “fittest”
o Darwin: “as many more individuals of each species are born than can possibly
survive; and as, consequently, there is a frequently recurring struggle for existence, it
follows that any being, if it vary however slightly in any manner profitable to itself,
under the complex and sometimes varying conditions of life, will have a better
chance of surviving, and thus be naturally selected. from the strong principle of
inheritance, any selected variety will tend to propagate its new and modified form.”
Resistance against the evolutionary theory
- People would not and could not believe
o Church still big part in shaping the world
o Darwin was not taken seriously
The tree of life
- DNA-studies reveal that humans share a common ancestor with bacteria, 4 billion years ago
- Build from the same DNA as we are
The primate tree
- based on DNA evidence
o Share DNA with non-human primate
- Share common ancestor: we are not descended from a chimpanzee
A walk through human evolution
- Only modern human left
- At different types different types of humans present
,Natural selection
Components of natural selection
- variation
o individuals are born with slightly different traits
- inheritance
o traits passed on from parent to offspring
- selection
o certain environment calls for certain traits
Natural selection process
- there is individual variation in traits (physical,behavioral)
- Some trait variants allow their bearers to better compete for resources
- if these traits are inheritable then they are passed on from generation to generation
- the result: individuals of a species become better adapted to their environments over time.
Genes
- mechanism for evolution using natural selection
- gregor mendel (1822-1884)
o understood that genes and traits are heritable
o found that different trait varieties are possible
DNA variation
1. mixing parental genes (mendelian genetics)
2. recombination
3. mutation
Sexual selection
Darwin
- Was searching for counterarguments to his theory
o Peacock: carries big tail which makes it an easy target
o However: explainable using sexual selection
- Peacock: carries big tail and makes itself easy prey
Forms of sexual selection
- inter sexual competition:
o traits passed on because they are good at attracting opposite sex mates
- intra sexual competition:
o traits passed on because they are good at winning same sex competitions for mates
- Still debated which is the most important in humans
, Runaway effect
- runaway selection: secondary sexual traits become genetically correlated with a preference
for the trait in the other sex
- can go really fast
Savannah hypothesis
- When or ancestors moved from the trees into the savannah new selection pressure emerged
o Only able to survive by creating groups
o Created changes in physical changes
Bipedalism: able to see more and get around more easily
The human brain: evolutionary history
- Brain function: Information processing organ
o transforms inputs from the environments into functions
- triune brain (maclean, 1960).
o reptilian brain, brain stem (avoid and approach)
ancestral brain: takes care of basic functions
o paleo-mammalian complex, emotions (limbic system)
takes care of primary emotions
o neo-mammalian complex, planning (neo cortex)
associated with higher intellectual functions
planning, makes us quite unique as primates
Increase in brain size over mya
- steady increase
- not linear increase
- does a big brain mean a smart brain
o difficult to determine
o probably not exactly correlated
Probable causes for increase in brain size
- ecology (climate, rainfall)
o physical environment is very challenging
- technology (tools, weapons)
o needed to able to get food by hunting
o able to use hand due to bipedalism
- social factors (need to cooperate)
o caused by social pressure due to living in larger groups
o to protect from predictors
o but more competition for resources
- cultural factors (social learning)
o ability to culturally learn from each other
o need/pressure to culturally learn from each other
