What is “an evolutionary explanation of behaviour?”

Travis DixonBiological Psychology

Does evolution influence behaviour, or does behaviour influence evolution?

Offering an evolutionary explanation of behaviour can be more difficult than it first appears, so I want to show two ways to do this.

I don’t teach evolution and behaviour as an individual topic in my course, as there are multiple behaviours that are applicable including fear, aggression (both in Criminology), attraction (Love and Marriage) and fear conditioning (PTSD). This means you can use the same content (including studies) to apply to more than one topic.

The basic explanation

  • We have evolved to behave in ways that will increase the chances of survival (and thus passing on our genes).

This is a simple and straightforward explanation that all students will be able to comprehend. It’s even enough to be able to write excellent SARs and essays, if the behaviour and the evidence are explained appropriately.

Here is one example that fit this explanation:


Attraction (from the Love and Marriage chapter): Men and women have evolved to find particular traits in the opposite sex attractive if those traits are signs that the person is a suitable mate to procreate wit (because they are a sign that they will be able to

Portrait of a handsome man with a light stubble

We’ve evolved to be attracted to signs of fertility, health and strong genetic material. These physical signs are often the result of sex hormones (e.g. testosterone and estrogen).

provide healthy offspring). For example, studies have shown that females prefer masculine facial characteristics at the time of ovulation, as this is when they’re most likely to become pregnant and masculine features are a sign of high testosterone which equates to healthy genetic material (and thus a good mating partner).


  • Johnston et al’s research on face preferences can be used to show the second point (textbook pg 278-79).

In this example, our “survival” doesn’t refer to our own individual survival, but the survival of our genetic material. This can be ensured if we procreate with someone who has strong, healthy genes, so we find these people more attractive than others.




The advanced explanation

  • We have evolved to behave in ways that will increase the chances of survival (and thus passing on our genes). The genetics that are passed on will influence our physiology in a way that promotes the adaptive behaviour.

In this second, more advanced, explanation the role of physiology in the behaviour is added. When we break it down we begin to see that it’s like a cycle: the behaviour helps genes being passed on and those genes facilitate that behaviour so it continues which helps genes being passed on so that behaviour occurs which results in genes being passed on… etc. etc.

This can get quite tricky, so in order to keep it comprehensible while still detailed I recommend that my advanced students aim to at least add to their basic explanation how the physiology underlies the behaviour.

A good question to ask students to get them thinking about this tricky concept is: “Does evolution influence behaviour, or does behaviour influence evolution?”

Fear is a good example for this more advanced explanation as it’s a healthy adaptation as we need to experience a fear response towards things that could harm us, and the underlying physiological processes that facilitate fear are well studied. When we experience fear our physiological arousal increases, which prepares us for the fight/flight response and this response is essential in helping us to deal with the fearful stimuli and thus, survive.


Fear is a healthy adaptation, as is the ability to learn to be afraid of something (fear conditioning).

The role of the amygdala in the perception of fearful stimuli could be one of the biological factors that is underlying this response. Studies have shown that our amygdala perceives threatening stimuli and activates our stress person before our conscious brain is even aware of it. This is a healthy adaptation as we need to respond quickly to threats or else our lives may be in danger.

  • Ahs et al.’s study on phobia and snakes using fMRI is good evidence for this (textbook pg. 78-79).

A common mistake I see in students responses to exam questions on this topic is that they dive straight into the studies, without first providing a full evolutionary explanation of the behaviour. It’s one of those topics that can be explored at almost never-ending depth, which is why I like to provide two options for how students approach this topic.

It’s often the case that I find the evolutionary explanations easy to offer, but explaining the supporting evidence is more difficult. This is another consideration for students as they select their material for exam revision.