Transcript evolution and natural selection

Biological Psychology (Darwin)
Evolution
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What is evolution & why are psychologists interested?
Reproductive behaviour
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How do men and women attract/choose sexual partners?
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How has evolution shaped sexual behaviour (e.g. jealousy, infidelity)?
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Has evolution affected how men & women approach child-rearing?
Evolution
Charles Darwin’s attempt to explain the huge variety of living things…
…in a scientific way
…without drawing upon religious ideas
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Evolution is not about progress (e.g. being the biggest, fastest or strongest).
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It is about adaptation.
Evolution and Adaptation
• Individual do not evolve, species evolve.
• This happens through the process of natural selection.
• The members of a species that are best suited / adapted to a particular environment will
survive and pass on their genes.
• The rest may die (or fail to pass on their genes).
• Consequently, future generations will be better adapted to the environment
(i.e. the species has evolved / changed).
Evolution
Each living thing (organism) has a set of characteristics encoded by its genes
The organism inherits its genes from its parent(s)
Variations between organisms are caused by variations in the genotype
Evolution
Organism
Environment
Organism has particular
characteristics
determined by its genes
Environment contains a
range of opportunities
and threats (e.g. food
sources, predators)
Evolution
An organism’s ability to survive depends on how well its characteristics allow it to:
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Exploit the opportunities available in its environment
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Avoid or deal with the threats presented by its environment
We call this the organism’s fitness
Fitness
Fitness
Yummy!
Evolution
Fit organisms are more likely to survive into adulthood than unfit ones.
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Consequently, they are more likely to mate and have offspring
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They pass on their genes to the next generation
Gradually, the genes for successful characteristics spread through the population
Evolution
Fitness is all about how well an organism is adapted to its environment
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The environment changes over time – sometimes gradually, sometimes rapidly
So a characteristic/gene that is adaptive at one time may become maladaptive
if the environment changes
Fitness
Arse.
Evolution
Genotypes change due to:
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Random mutation of DNA
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Recombination of genes due to mating
New species emerge as adaptive changes spread through a population
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Species compete with each other – the fittest ‘wins’ by reproducing more
effectively
Species go extinct when their environment disappears or they are out-competed
Evolution Myths
Characteristics acquired during the lifespan can be passed on to offspring
Humans are descended from monkeys
Other animals are ‘less evolved’ than us
Humans are the ‘end product’ of evolution
Evolution & Psychology
Evolutionary psychology regards humans as subject to same evolutionary processes
as other animals (continuity)
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Assumes that behavioural characteristics can be inherited just like physical ones
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Tries to explain human behaviour/psychology in terms of evolutionary processes
Evolution & Psychology
Slow
Physically weak
Lacking agility
Poor climber
Small teeth
No claws
Large brain
Planning
Imagination
Language
Social
organisation
Tool use
Highly dependent
young
Communication
Poor night vision
Problem solving