Evolutionary and Genetic Influences on Aggression Flashcards
What is evolution?
An scientific explanation of inherited characteristics in organisms (cellular level). These help distinguish species and can be positive (survival) or negative (extinction).
What are some pre-Darwin solutions to evolution?
Degeneration of species into each other
Organism modifications down to the cellular level
Lamarck - Parents chose their children’s characteristics for better environmentally survival
God’s Will
Why weren’t pre-Darwin solutions accepted by the wider world?
No hard evidence
What lead to Darwin’s “the survival of the fittest” theory?
He considered not all of he same organism would survive in a particular environment or even til reproduction - pivotal point.
Was Darwin the only one with this theory?
Wallace -1958- sent Darwin his ideas about the same theory though they came up with them separately
What is natural selection?
Some characteristics are better suited to a particular environment and therefore those organisms with those characteristics are more likely to reproduce.
What are some of Darwin’s key points about organisms?
They have more offspring than required.
Some characteristics aid survival
Some characteristics are inherited.
What did Darwin say about characteristics?
They aided survival chances until reproduction meaning that particular characteristic would be more prominent within the gene pool and become more common later on in the genetic line. The opposite would happen to ill-aiding characteristics and therefore those characteristics would die out.
What is an example of Darwin’s explanation of characteristics?
Finches with their beaks and environment - Suitable beaks become more prominent in order to aid survival
What are some other explanations of how organisms adapt in terms of inherited characteristics?
Genetic mutation - changing species or leading to new species
Random changes in passed on genes - genetic drift
How does genetic drift work?
If there is variance of genes within the species, genes become categorized. Variation comes form mutations but this is always small as many organism share most of the same genetics and characteristics ie. fight or flight.
What is genetic mutation?
Can be visible, have no obvious effect or prevent proper genetic function.
May not always be beneficial or visible: reason for DNA repair mechanism but this could also cause mutations
Why are mutations beneficial?
Advantageous mutations will change the genetic pool and could, in the long term, lead to a new species.
Where do you get mutations from?
Internal source or external sources ie. carcinogens (cancer)
Why is mutations only partially applicable to survival of the fittest?
Origin genes could also aid survival due to their “fit” characteristics.
What do we already know about an offspring’s genes?
They are 50/50 to each parent
What is the element of chance?
Some genes are lost - this reduces genetic variation and therefore by association, the gene pool
What did Fisher and Kimura think of the element of chance?
Fisher (1930) believed the element of chance was a minor setback in terms of evolution, in comparison to genetic mutation and natural selection.
Kimura (1968) on the other hand, believed it had a important role and is a factor in genetic changes in species.
Where do our characteristics come from?
Contrary to popular opinion, they mostly come from the environment rather than your genetics. Many are a combination of the two ie. height which can be affected by nutrition (nurture)
What forms the basis of natural selection?
Some advantageous characteristics are passed down from parent to offspring through reproduction.
Why has natural selection theory been criticized?
On the basis of animal observations, they also use altruistic behaviour such as warning others of danger. This contradicts natural selection in that a group is more important than a single individual.
How can you contradict the critics of natural selection?
Their critic doesn’t go against natural selection as animals warned are most likely family. In this way, genes of the individual are still passed on.
What is the critics of the critics know as?
Kin selection Theory
Define direct fitness
individual’s genes are passed on when it survives long enough to reproduce
Define inclusive fitness
Individual’s genes are passed on through relatives who survive long enough to reproduce
How is natural selection an example of adapting genetics?
They aim to survive the environment, rather than through a single individual. Disadvantaged genes may become advantageous in this way.
How can disadvantaged genes be advantageous in a group setting?
The closer an animal is to those around it, the more beneficial it is for it to use self-sacrificing behaviour to ensure the survival of the genetics
What are some examples of altruistic animals?
Vampire bats, ground squirrels and dogs
What is group selection?
Behaviour that protects the group thereby benefits the individuals within it as they may not otherwise survive individually ie. by gaining protection from predators or protecting resources
What did Wilson advocate?
A group can take care of offspring (multi- generational society) as they will have divisions in labour. As a community, they could take care of all necessary work
What is Eu-social?
The success of living within a group leads to survival of genes which promote co-operational behaviour.
What are some examples of eusocial behaviour?
Ants and bees
What is an interesting fact about eusocial behaviour?
Some species have evolved to not reproduce as this isn’t their function within the community but their roles are passed on via behavioural traits within genes - this goes against natural selection in a way
What are some problems with group selection theory?
The survival of any group using normal living conditions rather than eusocial cannot be explained using group selection theory - Human social behaviour is better explained as an individual who finds a group in order to gain better survival opportunities rather than survival of an individual’s gene.
It is an over generalised theory.
What does group selection theory suggest?
Social organisms are better within a group which they support by inserting themselves within a role but this goes against the idea of equality
What are the strengths of natural selection as a theory? (2)
Time resistant with evidence suggesting inherited characteristics to be possible through reproduction ie. Darwin’s Beagle Voyage (finches) and Kettlewell (1950s) found more camouflaged moths lived until reproduction age in comparison to non-camouflaged moths
Darwin used a good scientific method and reduces behaviour to genes and so we can focus on the genotype - learned and inherited characteristics can be observed
What are the weaknesses of natural selection as a theory? (3)
With reductionism, you cannot get the bigger picture - though behaviour can be observed and learned by associated, it doesn’t account for all behaviour ie. kin selection theory but you can also say he didn’t mean for it to cover everything
Wanted to confirm his theory rather than falsify it - falsifying it could lead to more proof
Creationism - beliefs are just as important as science
What does natural selection about human emotion?
Aggression and peace are human traits are have evolved, as much of our emotions, in order to survive ie. peace allows better chances of survival as its easier to fight off predators and live a longer life span