evolution, natural selection and aggression Flashcards
what is evolution?
the changes in inherited characteristics in a biological population over successive generations
what is natural selection?
the major process that explains evolution whereby inherited traits that enhance an animal’s reproductive sucess are passed on to the next generationand thus ‘selected’ whereas animals without such traits are less successful at reproductive and their traits are not selected
what is sexual selection?
an evolutionary explanation of partner prefernece. atrributes or behaviours that increase reproductive success are passed on and may become exaggerated over succeeding generations of offspring.
why do variations occur between organisms?
genes from parents are combined and also due to spontaneous mutations in genes.
- minor differences do not matter much when things are going well but when life is hard individuals who possess characteristics that help them stay alive are the ones who pass their genes on to others.
what is the process of natural selection?
after many generations of small differences, there are individuals who are different from their ancestors.
- natural selection is the choosing done by the environment
- this idea was proposed by darwin and is often called survival of the fittest.
why does natural selection occur?
natural selection is due to the survival of genes
- it happens when there is competition for scarce resources (including mates). the genes which are most useful are retained in the population and become more frequent over time (giraffes long necks)
- the outcome of selection is adaptation - the survivors are better suited to life in the current environment
what does sexual selection explain?
why some characteristics that might appear disadavantageous actually confer a survival advantage because they are characteristics that are attractive to potential mates
e.g. peacocks tail
- other characteristics are adaptive because they provide an advantage over competitors for reproductive rights - aggression is good because it allows to fend off potential reprocutive rivals
how does evolution and aggression aid in guarding your partner?
mate retention strategies are often the aggressive behaviours men use to retain their partners and prevent them from straying
- Wilson and Daly (1996) direct guarding involves male vigilance over a partners behavior
how does evolution and aggression aid in guarding your offspring?
human parents will direct aggressive acts against other people that threaten their children.
- this aggression is adaptive because each child is a valuable genetic commodity.
- aggression is a way for parents to protect their investment, increasing the offspring’s reproductive chance later in life.
- Steiner (2016) notes that protecting offspring is the one situation where females are as aggressive as males
what is a strength of the evolutionary theory?
it can explain why males are more aggressive than females
- females who are cooperative are likely to be naturally selected because it helps them protect themselves and their offspring as a group.
- reduced aggression in females is selected. males who are aggressive are more likely to be naturally selected because they make better hunters
what is the competing argument to the strength?
any evolutionary explanation is uncertain because it is impossible to test evolution directly.
- most research is correlational e.g. findings associations between mate retention behaviours and aggression.
- because variables are just measured and not manipulated, correlational research can never rule out the effects of other factors
what is a weakness of this explanation?
there are differences between cultures in aggressive behaviour.
- amongst the !Kung San people aggression is discouraged from childhood whereas the Yanomami people of brazil aggression is encouraged to gain status
how can this explanation be applied?
evolutionary theory can help us understand himan relationships as it predicts that we should choose partners who will enhance our reproductive success.
- Buss(1989) found that across 33 countries males preferred younger, more attractive women, presumably because this enhanced their reproductive success as they are more likely to be fertile whereas females preferred older, wealthier and hard-working men, which is likely to increase their reproductive success as they will be well-supported.
