Summary evolutionary psychology
Week 1:
Evolutionary psychology is the study of human behaviour, affect and cognition from an
evolutionary perspective. We use the evolutionary theory to understand why the human mind works
this way and how it has been designed. This means viewing humans as part of the animal kingdom,
subject to the same laws of evolution, natural selection, etc.
Evolution theory Jean-Baptiste Lamarck (1744-1829): Lamarck proposed that traits developed during
an organism's lifetime (like a giraffe stretching its neck to reach leaves) could be passed on to its
offspring. Use and disuse of traits: He believed that body parts used frequently would become
stronger or more developed, while unused parts would weaken or disappear over generations.
Evolution theory Charles Darwin (1809-1882);
- Natural selection and survival of the fittest: Darwin suggested that individuals with traits
better suited to their environment are more likely to survive and reproduce. Over time, these
advantageous traits become more common in the population.
- Darwin stated that because more individuals are born than can survive, there’s a constant
struggle for existence. Variations that offer even slight advantages will help some organisms
survive and reproduce more effectively, passing these traits on to the next generation.
Three components of natural selection:
Variation: Individuals in a species differ in their traits.
Inheritance: Traits are passed from parents to offspring.
Selection: Some traits provide a better chance of survival and reproduction, so they become
more common over generations.
How does natural selection really work: there is individual variation in traits (physical, behavioral,
etc.). 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.
Non-scientific theories:
- Creationism: creationism is the belief that the universe and life originated from specific acts
of divine creation, as opposed to natural processes such as evolution.
- Seeding theory: seeding theory, often referred to as panspermia, suggests that life on Earth
may have originated from microorganisms or chemical precursors of life that were present in
space and were brought to Earth via comets, meteorites, or cosmic dust.
Modern synthesis in biology and DNA discovery (1953):
1. Mixing parental genes (Mendelian genetics): Traits are inherited through genes passed from
both parents, following patterns discovered by Gregor Mendel.
2. Recombination: During reproduction, genes from parents mix, creating unique combinations
in offspring.
3. Mutation: Changes or errors in DNA can create new traits, introducing variation in a
population.
Two forms of sexual selection:
- Inter sexual competition: traits that are passed on because they are good at attracting
opposite sex mates, for example pretty feathers of birds.
, - Intra sexual competition: traits that are passed on because they are good at winning same
sex competitions for mates, for example stag fight.
The savannah hypothesis: this proposes that many of the key features of human evolution, such as
our bipedalism (walking on two legs), our social structures, and even aspects of our cognition, are
adaptations to living in a savannah-like environment rather than a forested one.
Leda Cosmides and john tooby, the adapted mind: the brain is a Swiss Army knife.
- The metaphor compares the brain to a Swiss Army knife, suggesting that the brain is not a
single, general-purpose organ but rather a collection of specialized modules, each designed
to handle specific tasks or problems.
Evolution has three products:
1. Adaptions: inherited characteristics that are naturally selected because they helped to solve
a problem of survival or reproduction.
2. By-products: carried along with adaptions but without function, for example a belly button.
3. Noise: random effects, no function, for example if a belly button is inside or outside.
- Mismatches: traits that used to be adaptive, but not anymore.
Psychological adaptions: evolved psychological mechanisms or if-then decision rules:
- Solves a problem related to survival or reproduction
- Takes in specific inputs
- Transforms it into adaptive outputs
- Outputs can be psychological, behavioural or combinations.
Levels of analyses in evolutionary psychology:
Biologically innate: language capacity, desire to eat food, desire for social status, desire to be
attractive.
Culturally acquired: languages, taste for food, money.
Why do babies cry, evolutionary explanation: elicits care and defensiveness from mothers and other
caregivers, which will increase the likelihood of survival and hence lead to fitness benefits.
Two strategies for hypothesis generation:
1. Bottom up: observation and then explain from theory
2. Top down: hypothesis from theory
Testing an evolutionary psychology hypothesis:
- Hypothesis from sexual selection theory: woman have an evolved preference for physically
stronger men.
- Prediction: men show off their physical strength to impress woman.
- How would you test this?
Field study: observe men’s behaviour in the gym when there are woman present
Lab study: show female faces on screen and have men do an arm wrestling with each
other
Cultural study: see if physically stronger men have a younger/more attractive wife in
various cultures.
Research methods:
- Psychological experiments: Studying behavior and mental processes in controlled settings.
- Cross-cultural anthropological studies: Comparing behaviors across different cultures.
, - Physiological and neuroscience measures: Examining the brain and body responses.
- Genetic studies: Investigating how genes influence behavior.
- Comparative research: Comparing different species to understand human behavior.
Human adaptions for survival: how to get food, solution: hunting
- Change from forest to grass lands with larger prey animals. Provisioning for and beyond
family.
- Selection for new adaptions: tool-making and weapon use, language or new practices as fire-
making and cooking.
The hunting hypothesis:
1. Hunters are mostly men. Men are primarily hunters.
2. Better hunters have: Better hunters gain more status, attract more and younger mates, and
can provide better for their children.
3. This pattern is seen in many hunter-gatherer societies.
The gathering hypothesis: this focusses on woman’s role in food gathering. The gathering hypothesis
suggests that women played a crucial role in gathering food, such as plants, seeds, and nuts. This
contributed significantly to the diet, although the exact amount depended on the region. The activity
of gathering created new evolutionary pressures, influencing human development and behavior.
- Large portion of diet can consist of plants, but depends on region.
- Gathering plants, seeds, nuts and created new selection pressures.
Evolutionary hypothesis: woman are on average better with object memory location and men are on
average better in spatial orientation.
Maybe because males have tended to do the hunting in ancestral times (which involves
tracking and following then finding way home) they are better at spatial tasks.
Maybe females are better in object location because of gathering past, which involves
remembering where something edible can be found.
Fears and their adaptive outputs:
- Flight: better run than die.
- Fight: better fight than die.
- Freeze: avoid detection.
- Faint: submitting when no escape. the
Disgust as adaptive emotion, possible functions:
1. Disease avoidance (food poisoning, flu). It prevents contact with things that could make us
sick, like spoiled food or contagious illnesses.
2. Avoidance of non-cooperative individuals (moral disgust). It helps us avoid people who
behave immorally or harmfully, promoting social cooperation.
Week 2:
Parental investment theory (trivers,1972) and sexual selection theory:
- The sex that invests more in offspring (typically the female) will be more discriminating or
selective about the mating.
- The sex that invests less in offspring will be more competitive for sexual access to the high-
parental investing sex.
Hypothesis: in humans, woman are the more investing sex. Hence, on average, woman are
somewhat more selective about potential mates than men.
