EXPLAINING AGGRESSION THROUGH EVOLUTION
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Survival traits are anything that helps an animal survive and reproduce. This can be things like speed and strength, but it can also be cunning or stealth. Things that attract mates (like the lion's mane or the peacock's tail feathers) are survival traits. So are things that help reach food (like the giraffe's long neck).
Humans have many survival traits. Important ones are intelligence, team work and using tools. |
Aggression is an important survival trait, which is why the limbic system and hormones produce aggression. Too little aggression and you don't get to eat or reproduce, too much and you get killed (like Higley's rhesus monkeys).
Genetic mutation is the idea that children are never the exact genetic copies of their parents. When reproduction occurs, the mother and the father both donate genes to the child, but the copying of genes isn't exact. These genetic differences are mutations.
Did someone say "mutants"?
Mutations don't give you exciting super powers. In fact, most mutations are bad, making you slightly more susceptible to some illness or another (like cancer or diabetes). But occasionally, a genetic mutation gives a slight advantage, like strength or a longer neck or more impressive feathers. A mutation like this becomes a survival trait.
When long periods of time pass, the tendency for genetic mutations to be naturally selected as survival traits add up and creatures can change massively, eventually becoming a different species altogether (this is "speciation"). Creatures with very short lifespans, like mayflies and viruses, can evolve dramatically in just a few years; creatures, like humans, with longer lifespans take millions of years to evolve.
When long periods of time pass, the tendency for genetic mutations to be naturally selected as survival traits add up and creatures can change massively, eventually becoming a different species altogether (this is "speciation"). Creatures with very short lifespans, like mayflies and viruses, can evolve dramatically in just a few years; creatures, like humans, with longer lifespans take millions of years to evolve.
Don't think that some creatures (like humans) are "more evolved" than others. They're not. All life forms are evolving. Because humans can use technology to alter their environment, there may be less pressure on us to evolve. Sharks are a good example of animals so well-adapted to their environment that they haven't shown many evolutionary changes in millions of years.
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Physical appearance and abilities aren't the only things that change because of genetic mutation and get passed on because of natural selection. Behaviours and thought processes change this way too. Evolutionary psychology looks at how our brain structures, our behaviours and our cognitions have been shaped by evolutionary processes.
9-minute video with a very simple explanation of Darwin's discoveries and natural selection
"Survival of the Fittest"
"Survival of the Fittest" is a phrase often wrongly attributed to Darwin (it was Herbert Spencer who used it to describe Darwin's theory). It sums up the Theory of Evolution in 4 words.
But bear two important things in mind about this phrase:
"Survival of the Fittest" is a phrase often wrongly attributed to Darwin (it was Herbert Spencer who used it to describe Darwin's theory). It sums up the Theory of Evolution in 4 words.
But bear two important things in mind about this phrase:
- What survives is not the fittest creature but the fittest genes. If a gene produces a survival trait (like speed or size or intelligence or aggression) it will survive because it will be passed on to children and grandchildren
- "Fittest" means "most suitable" or "most adaptive". It doesn't necessarily mean "strongest". A gene for intelligence or attractiveness might be fitter than a gene for strength or size. After all, intelligent and attractive people are more likely to marry and have children than big, strong people, right?
THE EVOLUTION OF AGGRESSION
Aggression is a human behaviour that may have evolved over time. Obviously, living together peacefully with other humans is an important survival trait and if anyone couldn't do that, they would be unlikely to live long enough to pass on their antisocial genes.
However, in other ways aggression may also be a survival trait. Our ancestors needed to use aggression to defend themselves and their children from predators. They also needed to use aggression to catch food. Aggression has fitness and so genes which produce aggression will survive. The most important survival trait is therefore the ability to switch aggression on and off. This is what the limbic system seems to do.
In humans, there is an additional complication because the pre-frontal cortex can consider these messages (which appear in your mind as "feelings") and decide to overrule them. This ability to ignore our instincts and choose whether or not to act aggressively is what enables humans to live together in complex groupings - another survival trait. THE ANIMAL MODEL
One consequence of the Theory of Evolution is that animals can tell us a lot about human behaviour. Studying animals to learn about humans is called ethology.
Lots of studies into aggression use the animal model, especially studies that focus on the "old brain" areas like the amygdala, which we share with many other animals. Animal studies like this include John Flynn's study of cats, Higley et al.'s study of rhesus monkeys and Ferrari's study of rats. |
APPLYING THE EVOLUTION OF AGGRESSION TO REAL LIFE
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EVALUATING THE EVOLUTION OF AGGRESSION
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EXEMPLAR ESSAY
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