We see aggression across the animal kingdom, this is interesting to psychologists because
it raises a question, are the aggressive feelings and behaviours we feel as humans unique to
us, and is we see in animals is a different process, or do we share some of the same features
of aggression with animals?
If that's the case, observing animals gives us an opportunity to study aggression removed
from all the social and cultural forces that are linked to human experience.
Linked to this idea is human evolution, aggression is clearly an evolutionary advantage to animals,
so is the same true with human evolution, and could the explanation for modern maladaptive
human aggression be a legacy from our violent ancestors.
Ethology The scientific study of animal behaviour is
ethology.
Now many scientists will study ethology to understand animals, but some psychologists
will study animal behaviour in order to apply this knowledge to human behaviour.
Now with wild animals it's easy to see the evolutionary pressures active in their day
to day lives, predator or prey they need to be aggressive to stay alive, when part of
a social structure they need to be aggressive to show dominance and win the right to mate.
When animals are observed, their aggression tends to be ritualistic.
What this means is when we look across a species all the members will show the same kind of
behaviour to the same kind of stimuli.
So taking wolves for example, they will growl, bare their teeth and puff up the hairs of
their back to look bigger.
Or if showing submission they will roll on their back and show their belly.
It doesn't matter what wolf pack you observe, you will see the same behaviour.
Lorenz has an explanation for this, he argued that aggression builds up inside animals as
a drive.
Like a hunger or sex drive.
But he suggests aggression isn't expressed all the time because there is a neural circuit
in the brain stopping aggression, this is called an innate releasing mechanism.
The innate releasing mechanism can be released, triggered by external stimuli.
So a wolf sees a member of another pack in their territory.
This then causes the wolf to display a predictable set of aggressive behaviours, which we call
a fixed action pattern.
So to be clear, these fixed action patterns are innate, they are shared across a species,
the animal does not have to learn them from other members of its species.
Let's have a look at two examples in the research evaluations.
Ethology - Research evaluations.
The first research study is by Tinbergen.
Sticklebacks show a clear fixed action pattern of aggressive attack when another male approaches
their nest.
Tinbergen wanted to find out what was setting off their innate releasing mechanism.
So he used wooden models and presented them to sticklebacks.
One wooden model was realistic, but only lacked the red belly of the stickleback.
The other wooden model was unrealistic, but had a painted red underside.
Tinbergen found the males only attacked the unrealistic painted model.
This suggests that sticklebacks do have an innate releasing mechanism, triggered by objects
with a red belly.
And when triggered sticklebacks will perform a fixed action pattern.
Well sticklebacks are fish, and you may think well they are simple creatures, that’s not
something we can really apply to humans, which is a fair evaluation.
But what if we look at primates?
Sackett took baby monkeys from their mothers and raised them in total isolation so they
couldn't learn any behaviour through observation.
He then exposed the monkeys to pictures of monkeys in either aggressive or non-aggressive
poses.
Sackett found when exposed to the aggressive poses that the monkeys would show defensive
poses typical for their species . Keep in mind there is no way that the monkeys
could have learnt what an aggressive monkey looked like, so the only explanation is the
monkeys are born with an innate understanding of what an aggressive posture is, and how
to respond to it.
This is evidence then for innate releasing mechanisms in animals that are closely related
to humans.
So when applying this to humans we have a mixed picture, researchers can do with these
studies what they could never ethically do with human participants, separate biological
from social cultural processes to see what aspects of aggression are purely biological.
But of course the application to humans is limited, perhaps some aggression is instinctual,
especially in fight or flight responses but much of human aggression is premeditated,
like warfare for example, and a significant amount of aggression is non physical.
Evolution Evolutionary theory does suggest that aggression
in humans is due to biological forces, and is due to the survival advantages that it
gave to our ancestors.
This basically means by being aggressive you don't die long enough to be able to mate,
have children and see that those children live long enough that they have children themselves,
passing your aggressive genes on into the future.
So precise examples of aggressive behaviours would be surviving predator attacks.
Fighting other members of your species and competing with other species for access to
resources.
And being aggressive enough that a potential mate sees you as able to offer protection
for them and their offspring.
A species can become more aggressive over time because genes can mutate, and if the
mutations that cause increased aggression make the individual more able to complete
then their genes will be selected for and become more common in the gene pool.
Evolutionary theory also is used as an explanation for variations in aggression between males
and females.
Male sexual jealousy is thought to be particularly extreme as males cannot be certain of paternity
in the same way that females can be.
From an evolutionary perspective it's a total waste to be spending limited resources on
raising a child that is not genetically related to you.
So on this basis it makes evolutionary sense for males to to show aggressive mate retention
strategies, like mate guarding, limiting the access females have to other males, and the
use of threats regarding infidelity.
Evolution - Research Evaluations A pretty disturbing support for evolutionary
ideas on aggression comes from Daly and Wilson.
This was a comparison of murder rates in families looking at how frequently blood and non blood
relatives killed each other.
This data analysis showed across the world someone is far more likely to be killed by
a non genetically related family member, so partners and step children.
One horrific finding was infant children in the US were 100 times more likely to be killed
if one or both of their parents were not genetically related to them.
This does match the predictions of evolutionary theory, if the parents are not related to
a child then they wont gain an evolutionary advantage from raising it.
In fact the resources they spend on it are resources they can't spend on their own children.
Now an interesting counter to the argument that aggressive males are more attractive
to potential mates, is considering the role of dominance, now dominance doesn't have to
be aggressive, it's characterised by competition, authority, control and an attempt to achieve
high status.
Sadalla gave female participants written descriptions of males that were either high or low in words
that described them as dominant, aggressive or domineering, which is someone who gets
their own way by being bossy and arrogant.
Interestingly it was found that the females did rated the males who were highly dominant
as more sexually attractive.
But being highly aggressive or domineering males were not rated as more attractive, in
fact they were rated as less likable, less stable and more likely to be promiscuous.
Features that are not wanted in a long term romantic partner.
It seems the most attractive partner is someone who can achieve dominance without resorting
to aggression.
This makes sense, a highly aggressive partner is a danger to the woman and her offspring.
We do also have to consider the ethical implications of this theory, by suggesting that males are
aggressive due to their evolutionary history, could this be used as a justification of male
violence towards women?
With men claiming not to be responsible because aggressive impulses are just in their nature?
And also looking across cultures, and even different time periods in the same culture
we can see big variations in the levels of aggression males show.
For example in the last 30 years or so there has been large reductions in the amount of
violent crimes committed.
Evolution is a slow process that takes many generations, and explanations surrounding
socialisation may be better able to explain these differences.