Biological Psychology (Darwin)

1. Biological Psychology (Darwin) • Evolution • What is evolution & why are psychologists interested? • Reproductive behaviour • How do men and women attract/choose sexual partners? • How has evolution shaped sexual behaviour (e.g. jealousy, infidelity)? • Has evolution affected how men & women approach child-rearing?

2. Evolution • Charles Darwin’s attempt to explain the huge variety of living things… …in a scientific way …without drawing upon religious ideas • Evolution is not about progress (e.g. being the biggest, fastest or strongest). • It is about adaptation.

3. 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).

4. 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

5. Environment Organism Organism has particular characteristics determined by its genes Environment contains a range of opportunities and threats (e.g. food sources, predators) Evolution

6. Evolution • An organism’s ability to survive depends on how well its characteristics allow it to: • Exploit the opportunities available in its environment • Avoid or deal with the threats presented by its environment • We call this the organism’s fitness

7. Fitness

8. Fitness Yummy!

9. Evolution • Fit organisms are more likely to survive into adulthood than unfit ones. • Consequently, they are more likely to mate and have offspring • They pass on their genes to the next generation • Gradually, the genes for successful characteristics spread through the population

10. Evolution • Fitness is all about how well an organism is adapted to its environment • 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

11. Arse. Arse. Arse. Fitness

12. Evolution • Genotypes change due to: • Random mutation of DNA • Recombination of genes due to mating • New species emerge as adaptive changes spread through a population • Species compete with each other – the fittest ‘wins’ by reproducing more effectively • Species go extinct when their environment disappears or they are out-competed

13. 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

14. Evolution & Psychology • Evolutionary psychology regards humans as subject to same evolutionary processes as other animals (continuity) • Assumes that behavioural characteristics can be inherited just like physical ones • Tries to explain human behaviour/psychology in terms of evolutionary processes

15. Evolution & Psychology Slow Physically weak Lacking agility Poor climber Small teeth No claws Highly dependent young Poor night vision Large brain Planning Imagination Language Social organisation Tool use Communication Problem solving