Week 7 (Evolutionary and Comparative Psychology) Flashcards
Lamarck
First to propose ideas of ‘higher’ forms & inheritance of traits
Mendel (1865)
Proposed inheritance to be particulate (through genes)
Malthus (1798)
Argued would over-populate if all survived & reproduced
Darwin + Wallace
Proposed theory of natural selection
Natural Selection
Darwin’s (1859) idea was inspired by the finches of the Galapagos, which were distinct from one another. Led him to propose that they had the same ancestor but differed due to having different ecological niches.
How does natural selection work
- Appearance of a new trait (mutation)
- Trait increases reproductive success
- Increases chances of survival
- Is passed onto offspring
-Variation
-Inheritance
-Differential reproduction
-Adaptation
Misconceptions of Evolution
-Evolution is not forward thinking (intentional)
-Tends to be gradual but can have punctuated equilibrium
Evolution of the Nervous System
-Because all animal species are related, so are the brains and behaviour
-Complex brains and behaviour evolve from simpler brains and behaviour
-Complex behaviour includes learning
Evolution of Brains
-First animal with brain cells appeared 700 million years ago
-First brain appeared 250 million years ago
-First human brain appeared 3-4 million years ago
-Modern human brains appeared around 200,000 years ago
-Evolution of more complex behaviour is linked to the development of the cerebral hemispheres and cerebellum
-More folding in more recently evolved groups
The most common misconception of human evolution
We are not descended from apes, we share a common ancestor with them
Order of how we evolved
-Distant ancestor : Australopithecus
-Homo Habilis
-Homo Erectus
-Homo Neanderthalensis
-Homo sapiens
Australopithecus
Our distant ancestor, first on our timeline
-Brain 1/3 of ours
-Walked upright
Homo Habilis
2nd on our timeline
-Used tools (2.8 million years ago )
Homo Erectus
3rd on our timeline
-1st in Europe & Asia (until 100-30,000 years ago)
Homo Neanderthalensis
4th on our timeline
-Larger brains
-Communicated with language
Homo Sapiens
Last on our timeline
-Coexisted/bred with above
Encephalisation Quotient
-Past 4 million years: Increased body size; disproportionate increase in brain size
-EQ: Index of brain to body size
-Calculated by comparing adult brain size to what one would expect given the animal’s body size
-Homo sapiens have the largest EQ
-Large EQ = More complex behaviours
-Overall number and density of neutrons also important
-EQ’s are more informative within a closely related group (primates) because density is constant
Human Brian Enlargement Theories
-Climate change
-Lifestyle
-Physiological changes
-Slowed maturation (neoteny)
How could climate change enlarge human brains?
-New environments
-Rapid selection for adaptive traits
How could lifestyle enlarge human brains?
-Complex foraging
-Complexity of social life
How could Physiology changes enlarge human brains?
-Enhanced brain cooling
-Reduced size of facial muscles
How could slowed maturation (neoteny) enlarge human brains?
-Adults retain some infant characteristics - large head
-Longer pre/neonatal period for brain cell production
Maturational Changes
-Do humans brains just grow more?
-Evidence from brain development suggest changes in the development processes
-Neubaber & Hublin (2012) argue for an additional development phase (globularisation) prior to the later phases shared with other apes (chimpanzees)
Frugivorous Primates
Fruit eating in primates is associated with larger brain size
-Studies comparing hippocampus size in birds that cache food with controls (non caching birds)
Technical Brains
Larger brain size is associated with innovation and technical ability
-Overington et al. (2009) find a relationship between innovation diversity (novel foraging techniques) and brain size in birds
Social Brain Hypothesis
Larger brains evolved with increasing social complexity
-Brain size is about group size (Jolly, 1966; Humphrey, 1976)
-Dunbar (1998) characterised is at the number (and later quality) of relationship
-But variations include the Machiavellian intelligence hypothesis (Byrne, 2022) that emphasise competing with group mates
Is there one explanation for human brain enlargement?
-DeCasien & Higham (2019) looked at relationship between ecological and social aspects of primate specialisation and different brain areas
-They suggest a ‘mosaic” evolution that reflects specialisation
Why use animal models?
Tinbergen’s 4 questions
Ultimate
-Function: Adaptive value/ contribution to fitness
-Evolution: Phylogenetic context of behaviour
Proximate
-Development: Ontogeny of behaviours (imprinting, learning)
-Causation: Hormones, genes, nerve, impulses, cognition controlling behaviour
Function of Voles (Tinbergen)
-Prairie voles widely dispersed: in low-density populations, a male that left a female would have difficulty finding another
-Given environment they live in, monogamy is a more successful mating strategy
Evolution of Voles (Tinbergen)
-Ancestral species was probably polyamorous then there was a shift towards monogamy
Development of Voles (Tinbergen)
-Development changes in social behaviour towards male and female peers
-Corresponding neural changes oxytocin receptor and vasopressin 1a receptor
-Oxytocin and Vasopressin are both hormones that act as a chemical messenger in the brain and are associated with may functions (including social interactions such as mother-infant bonding)
Causation of Voles
-Vasopressin released during copulation binds V1a receptors in ventral palladium in prairie vole. Providing positive feedback for their behaviour
-Adding vasopressin receptors to the ventral palladium in meadow voles increased bonding behaviours
-Prairie voles also have a higher number of oxytocin receptors in nucleus accumbens, which play a role in including pair bonds
-Giving montane voles oxytocin and vasopressin for >6 hours of co-habiting leads to a monogamous pair bond
-BUT prairie voles can still bond if engineered to lack oxytocin receptors
