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Lecture 1

Lecture 1:
What Is evolutionary psychology?
• Relatively new discipline
• Assumes that the human mind is the product of natural selection just like any other
• We gain a better understanding of the mind by understanding evolutionary pressures.
• When trying to understand cognition/phenomenon (especially in a non-human species)
we always try to relate it back to evolution
Darwin’s theory of natural selection:
Tenets (principles) of Natural Selection:
• Variation (individuals within a species display differences in both
physiological and behavioural traits)
• Heritability (Offspring inherit traits from their parents)
• Survival and reproduction (individuals with traits that best promote
survival have best chance of transmitting traits to offspring)
• ***A premise of comparative cognition is that cognitive traits are
shaped by the same selective pressures***
“Fitness” = ability to survive and reproduce
Natural Selection = The process by which inherited traits become more or less
prominent in a population due to differences in fitness.
We often discuss natural selection in terms of physical traits…cognition, however, is
assumed to be subject to the same selective pressures.
- Speciation involves the splitting of a single evolutionary lineage into two or more
genetically independent lineages.
- Geographic isolation of different finches caused great morphological differences
- Beak size/structure was tailored to food sources on specific island they occupied
- adapted until they became different species
- He also looked at artificial speciation in dogs (can be done in relatively little generational
- ex: breeding foxes experiment, was able to domesticate them wildly until they
very much resembled dogs in just a few generations
- Was interested in dogs as he observed the morphological differences in dogs,
informed his theories
- Many properties of living things are adaptations:
- Features that appear designed to serve a function.
- Hoverflies are palatable to birds but are protected by their resemblance to wasps.
Hoverflies are not dangerous to birds like wasps are but they look like wasps so
the birds avoid them
- Wasps taste bad and sting the bird
Conspicuous aposematic colour and pattern make it easier for predators to form an
association between the distastefulness of Hercules moth larvae and their appearance
- The yellow spikes are a signal to the birds not to eat it.
- if the birds eat it it will become sick and never touch it again
- Classical conditioning: they become averse to it
The peacock’s tail:
• Problematic for Darwin
• “The sight of a feather in a peacock’s tail, whenever I see it, makes me sick (Darwin,
• Evolution is not supposed to be about fitness. Peacocks are not a predator. If they are
the prey than why do they make themselves so visible and an easy target?
Birds of paradise:
- A group of birds that live in new Ginneau
- They all have special colorful and elaborate and behaviors
- This is so they can mate
- The cost of a predator is outweighed by the benefits of mating and being able to pass on
your genes
Hierarchical organization of life
- Many groups show minor variations within the group and large differences between
- Shorebirds: long legs
- Hummingbirds (Phaethornis): long beaks
- Euphonia: small and roun
- Evolutionary tree of species and subspecies
- Selective pressures for each species guided the length of beaks and tails
Linneaus is the father of taxonomy
Taxonomic classification is written as Genus
- ex: Vulpes vulpes or Panthera leo
Taxonomy of the Lion (Panthera leo)
Kingdom: Animalia (animals)
Phylum: Chordata (vertebrate animals) Class: Mammalia (mammals)
Order: Carnivora (meat eaters)
Family: Felidae (all cats)
Genus: Panthera (great cats)
Species: leo (lions)
Phyla of animals in the kingdom Metazoa
- Bryozoan, porifera, echinoderms, cnidaria, annelida, nematode, platyhelminthes,
chordata, mollusca, arthropods
Evolutionary Tree
- The closer the species are to each other on the tree, the more traits they share.
- i.e. if we share a trait with fish it shows its importance because our last shared ancestor
was way back
Niko Tinbergen (1907-1988)
Ultimate VS proximate causes
• Ultimate cause: those that are cast at the level of design by natural selection
• Proximate cause: those that directly cause a particular behaviour
What behaviour accomplishes (ie: what is its adaptive value?)
May help:
• Attract a mate
• Avoid predation
• Find food
• Maintain a stable body temperature
• Migrate
• Build a nest
How behaviour emerges on an evolutionary time scale
- Effect of natural selection
- Evolutionary descent: Phylogeny
- Change in species in response to selection
Development (ontogeny):
How behaviour emerges over time in an individual
• Early experience
• Nutrition, stress
• Learning
• Influence of parents, siblings
• Interaction of genes and environment
• Epigenetics
Factors that make behavior happen
• External events, stimuli from the environment
• Other animals
• Neural activity in the brain and nervous system
• Hormones
• Information in memory
Humans are special…aren’t they?
• Copernicus: The Earth is not the centre of the universe.
• There must be something beyond our world
• Freud: Instincts aren’t rational…they are emotional and sexual.
• Darwin: We are descended from apes, not angels
• We weren’t placed here in the 7 days of creation as religion has us believed
Ancient Belief Systems
• Many based on a God/religion, but not all
• Thales (624-545 BC)
• Empedocles (495-435 BC)
• Immanuel Kant (1798)
• Erasmus Darwin (1731-1802)
• Jean-Baptiste Lamarck (1744-1829)
Gregory Mendel:
• Experiments with hybrid Pea Plants (1858-1875)
• Discovered that inheritance was particulate.
• Discovered incomplete, dominant, recessive in terms of genes
Teaching the controversy:
• Scopes ”Monkey Trial” (1925)
• Highschool teacher taught evolution and was arrested and put on trial
• movie: Inherit the Wind
• December 2005: It is ruled in the U.S. that creationism is not a science and cannot be
taught in the classroom as such.
• -Can still teach creationism but cant teach it as a SCIENCE
- The feathered dinosaurs
- Against genesis: evidence birds at time of dinosaurs (proves religion wrong)
The creation museum:
- Museum said god created ALL life of earth in 6 days
- Therefore, dinosaurs and humans must have existed at the same time
This contradicts the fossil record.
Richard Dawkins:
• Gene-centered view of evolution
• “We are survival machines—robot vehicles blindly programmed to preserve the selfish
molecules known as genes” (Dawkins, 1976, p.xxi)
• In other words, our genes are not for our benefit, we are for theirs.
• Altruism is not for the group benefit, per se.
• We are a vehicle for transmitting genes to our offspring
The “Four Horsemen”
• Richard Dawkins
• Daniel Dennett
• Sam Harris
• Christopher Hitchens
• ”New Atheist” Movement
- Watson
- Skinner
Studying Psychology within an Evolutionary Framework:
• 1. Organizes known facts parsimoniously
• 2. Provides guidance to important domains
• 3. Leads to new predictions
• 4. Unifies psychology with the life sciences