Ethological Explanations of Aggression

Have you ever snapped at your parents or thrown your controller after losing at your favourite video game? Consider another response. Have you ever growled at your parents and hissed at them? Probably not. Even though humans display aggression differently from other animals, some theories propose that the same mechanism triggers aggression across species. So, do we have the same aggressive impulses as other animals?

Ethological explanations of aggression explore aggression in animals, and a few prominent theories attempted to apply these explanations to human aggression, too.

• First, we'll look at the aggression psychology definition, focusing on ethological explanations of aggression.
• Next, we'll outline the different types of aggression and associated behaviours.
• Then, we'll jump into the theories of aggression, including the biological theories of aggression.

• We'll describe the ethological explanation of aggression, including the role of innate releasing mechanisms and fixed action patterns in the animal kingdom.

• Finally, we'll evaluate the ethological explanation of aggression as applied to human beh

Fig. 1: Ethological explanation of aggression proposes that aggression is an automatic, evolutionary mechanism shared across species.

Aggression: Psychology Definition

Aggression in psychology is defined as acting with an intention to harm someone who does not want to be harmed (Baron & Richardson, 1994). Aggression can be associated with emotions like anger or rage, but the two do not always co-occur.

In the above definition, harm can take many forms, it can be physical or psychological, and it can involve acting to spite the other person, destroying their property using insults, threats, or violence.

What are the Types of Aggression?

We can distinguish different types of aggression based on how it is expressed.

We can also differentiate between emotional and instrumental aggression.

Theories of Aggression

There are several theories of aggression, ranging from biological explanations to cognitive and socio-cultural ones. Below, we'll describe the ethological explanation for aggression in detail and contrast it with other explanations by outlining the biological explanations for aggression.

The Ethological Explanation of Aggression

Ethology is the study of animals in their natural environment to understand the evolution of behaviour. The ethological explanation of aggression defines aggression as an instinct common to humans and animals. It attempts to understand this instinct by studying other animal species.

In 1966, Lorenz and Latzke defined aggression as:

There are two important assumptions behind this definition:

• Aggression is an instinct, an innate, genetically determined mechanism rather than a learned socio-cultural behaviour.
• We can generalise the findings from animal studies of aggression to humans, as this instinct is common to both.

According to the ethological explanation, aggression evolved because it had an important function that was adaptive, meaning it helped the species survive and successfully reproduce.

• This explanation proposes that within-species aggression is a communicative signal rather than violent and lethal behaviour.
• Signals of aggression are usually performed ritualistically; the stronger animal aims to force the weaker one to relocate rather than kill them. This is thought to be adaptive as it helps reduce competition for resources and the threat of starvation without destroying the members of one's own species, as killing members would be counterproductive in the grand scheme of species survival.

Innate Releasing Mechanisms (IRMs) and Fixed Action Patterns (FAPs)

The ethological explanation conceptualises aggression as a sequence of stereotyped and automatic behaviours called a Fixed Action Pattern (FAP). FAPs are triggered by the activation of a neural structure – the Innate Releasing Mechanism (IRM), which responds to very specific environmental stimuli.

Six features characterise FAPs. They involve a set of actions carried out in an unchanging order, which is universal across the species and unaffected by learning. The behavioural response is specific to a stimulus that triggers it and must be completed in full once initiated.

In summary, ritualistic aggression means that the behaviour is:

1. Stereotyped: involves an unchanging sequence of actions.
2. Complex: involves a set of behaviours.
3. Species-characteristic: universal for all individuals within the species.
4. Released: Triggered by a specific stimulus.
5. Triggered: Once the response is triggered, the ritual must be executed fully.
6. Independent of experience: it is innate rather than learnt.

Tinbergen (1947): Male Sticklebacks

Male sticklebacks go through behavioural and biological changes during the spring mating season. Their hormone levels change, their bellies turn red, and they become highly territorial – if another male enters their territory, a highly aggressive FAP is triggered.

To investigate what stimulus or feature of the other fish specifically releases this response, the researchers created different wood models of fish, adding or removing some features systemically.

• They found that it was the red underbelly that released the FAP. Even if the model did not look like a fish but had the red mark on it, the fish would attack, while a realistic fish model without the red mark would not result in an aggressive response.

• Moreover, Tinbergen has found that even if the fish was isolated from all the others and never saw the aggressive response in their environment, they would still instinctively engage in the response. This shows that aggression in sticklebacks is an innate, instinctive response consisting of FAP and released by a specific stimulus (red underbelly), which supports the ethological explanation of aggression.

Fig. 2: Tinbergen explored fixed action patterns in male sticklebacks.³

Adaptive Benefits of Aggression

The ethological explanation proposes that aggression evolved because it is adaptive; the individuals who are aggressive in a species are thought to have a better chance of survival and reproduction.

We already mentioned the first adaptive benefit of aggression – scaring away the competitor without within-species killings. However, this is controversial, as researchers have found planned lethal acts of aggression in chimpanzees. The aim of warfare is often not just to scare the competition away, but also to kill the out-group members.

Another adaptive function of aggression is to assert dominance. Individuals who can assert dominance in a group can establish themselves in a hierarchy and gain access to resources, such as territory or females.

Aggression has also been linked to mate retention. Females may favour aggressive males as they can protect them and their offspring.

Some psychologists propose that since males have to invest time and effort into an offspring but can't be certain about their paternity, they evolve more intense sexual jealousy, which can motivate aggression to prevent infidelity. This is often proposed to be the reason for male vigilance or even violence towards females.

Biological theories of aggression aim to explain aggression in terms of biological mechanisms. There are three biological theories of aggression.

• The neural explanations focus on the involvement of neural structures like the limbic system in aggression or the role of neurotransmitters like serotonin.
• The hormonal explanation looks at the role of testosterone, serotonin, and sometimes cortisol, and how it could explain variations in aggression between males and females.
• The genetic explanation for aggression highlights the genetic correlates of aggressive behaviour.

Evaluate the Ethological Explanation of Aggression

The strength of the ethological explanation of aggression is that empirical research supports the existence of Fixed Action Patterns and Innate Releasing Mechanisms in animals. Moreover, there's evidence suggesting that aggression has an innate character.

As well as this, ethological explanations also explain why humans may kill other humans. Despite other animals backing down when in lethal range, humans haven't developed this response because they didn't have to. Human's typically do not have the means, without weapons, to kill other members of the same species easily, so evolving the need to back down wasn't prioritised—advancements in weapons allowed for killing more easily.

However, it isn't easy to generalise the ethological research to humans.

• In contrast to many animals, we can regulate our emotions and behaviours; we might also have different motives for aggression.

The sole focus on the automatic, innate elements of aggression is also what makes the ethological explanation reductionistic. An explanation that doesn't account for the role of cognition (the thought process), emotions or culture is unlikely to reflect the complex processes associated with aggression in humans accurately.

Even though there are common elements to how we express aggression as a human species, evidence shows that there are cultural differences in aggression. This demonstrates that aggression can be influenced by socio-cultural factors rather than being an utterly innate instinct.

The ethological explanation of aggression is also deterministic. It proposes that when a specific stimulus triggers us, we are bound to react with a sequence of aggressive behaviours. This conceptualisation doesn't leave any space for free will or choice in terms of the way we respond.

Finally, aggression is socially sensitive and has important implications for how we treat aggression in society. If we assume that aggression is an automatic instinct we have no control over, it would mean that we can't punish perpetrators of violence as they are technically not truly at fault. It is a biological response. It's, therefore, important that the ethological explanation is not used to justify aggression or abuse.

Fig. 3: Aggression is a socially sensitive subject, it's important to not justify or undermine its impact on the society.