06. Evolution and Aggression Flashcards
Define genotype.
-Instruction from our genes which occurs at conception and provides the genetic code for how an individual develops.
-We inherit 50% of our genes from our mother and 50% from our father.
-It determines characteristics such as eye colour and natural hair colour.
Define phenotype.
The characteristics shown by a person that have occurred because of their genes and the environment.
Define evolution.
The changes in inherited characteristics (genotype) in a biological population over successive generations.
How can the role of evolution explain sexual differences in aggression?
-Evolution can also explain why males and females display aggression in different ways.
-For example, males are more physically aggressive than females because they need to physically fend off potential male rivals to ensure that they are able to reproduce and pass their genes on.
-Females on the other hand are verbally aggressive towards other females so that they can dominate other female rivals to ensure they are more attractive to males, so they can reproduce and be protected. Females also need to protect their young and can use aggression to do so.
Define natural selection.
The major process that explains evolution whereby inherited traits that enhance an animal’s reproductive success are passed on to the next generation and thus ‘selected’, whereas animals without such traits are less successful at reproduction and their traits are not selected.
Describe the role of evolution and natural selection in aggression.
-When sexual reproduction occurs at conception, there may be a mutation which causes a change in the individual.
-Eg a beak of a bird may be longer than average. If this is useful in the environment, eg enables the bird to peck at wood to get insects which other birds can’t reach, then the mutation makes it ‘fitter’ than the other birds which don’t have this genetic mutation.
-Therefore, if the random mutation at conception makes them likely to survive to reproduce then this will be passed on to their offspring. Birds with shorter beaks may starve and therefore will not reproduce, so in the population over many generations, birds average beak length changes.
-Therefore genes which are adaptive in a specific environment and increase the animals chance of survival will be passed on through reproduction, and the animals who don’t have the survival traitors will die off before passing on their genes to the next generation.
Define sexual selection.
An evolutionary explanation of partner preference. Attributes or behaviours that increase reproductive success are passed on and may become exaggerated over succeeding generations of offspring.
Describe the role of sexual selection in aggression.
-Sexual selection explains why some characteristics are more attractive than others to potential sexual mates.
-This is because some traits are viewed to be more beneficial when attracting a potential mate. For example, aggression may be attractive and therefore adaptive because it enables males and females to fend off potential threats such as sexual rivals, which is explained by sexual selection.
Define genes.
They are inherited segments of DNA that make up chromosomes that code physical features (eg eye colour) and psychological features (eg intelligence).
Define natural selection.
The major process that explains evolution whereby inherited traits that enhance an animals reproductive success are passed on to the next generation and thus ‘selected’, whereas animals without such traits are less successful at reproduction and their traits are not selected.
Define survival of the fittest.
Any characteristic of behaviour that increases the chance that an individual will survive and reproduce, would be passed on to the future generations.
Define environment of evolutionary adaptation (EEA).
This is the environment to which a species is adapted and the set of selective pressures that operated at this time.
Describe the process of natural selection.
-Within a species there are genetic differences which cause variation.
-This variation arises because genes from parents are combined to produce offspring and also due to spontaneous genetic mutations in the DNA.
-Members of the same species are in competition with each other for resources (eg food, territory, mates).
-The individual who possess characteristics that are advantageous (help them to survive and reproduce) pass on their genes to the next generation. Whereas the individual who cannot survive or fail to reproduce do not pass on their genes.
-This means ‘only the fittest survive’ which are those individuals best suited to the environment.
-The genes that are responsible for the advantageous trait as passed onto offspring and overtime become more frequent in future generations.
