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Rethinking The Reptilian Brain... and Emotions

By Dr Sarah McKay

The lizard brain: the myth lurking in every coaching conversation

Have you noticed the lizard brain lurking in the pages of self-help books, leadership pep-talks, sales and marketing presentations, life-coach Instagram posts, and even psychology textbooks?

  • “Lizards can’t be leaders!”

  • “Stimulate your customer’s lizard brain to make a sale.”

  • “The reptilian brain and how it can stop your child from learning.”

  • “The reptilian brain has the power to block therapy.”

Two places you’ll rarely find a lizard brain is lurking within the pages of contemporary neuroscience or evolutionary biology textbooks. Why? Because the concept is widely discredited by neuroscientists and evolutionary biologists: the model is out-of-date and not based on contemporary science.

Origins of the reptilian brain myth

The concept behind the ‘triune brain’ or ‘reptilian/lizard brain’ was proposed back in the 1960s by neuroscientist Paul Maclean. MacLean suggested that the human brain is divided into three layers that each emerged in succession in the course of evolution. The oldest, the ‘reptilian brain’ or ‘r-complex’ controls basic functions such as breathing, body temperature and heart rate. Next, the limbic system controls emotional responses. Finally, the cerebral cortex controls language and reason. Despite McLean originally tagging the basal ganglia as the reptilian brain, I’ve seen the phrase used to describe or label almost every brain structure except for the pre- frontal cortex!

Here are some examples where the reptilian brain is randomly labelled: brainstem and cerebellum, hypothalamus, amygdala, • and some structure in the middle of the brain that is possibly the thalamus?

It is widely used by therapists, coaches and ‘gurus’ to explain human behaviour, and most often to describe our response to threats via ‘fight or flight’ responses. The model especially appeals to psychotherapists because it seems to give biological credence to Freud’s theory of personality with the id, ego and superego mapping neatly onto the reptilian, limbic and cortical brains.

Or it’s used to explain the irrationality of human behaviour whereby emotions dominate rational thought or logic. In fact, MacLean called the limbic system the ‘paleomammalian complex’ and put that in charge of emotions and ‘fight or flight’.

This utter lack of consistency, vagueness and confusion is perhaps a clue it’s arather useless descriptor!

Our brains did not evolve from lizards

A recent, and entertainingly titled paper, Your Brain Is Not an Onion With a Tiny Reptile Insidepublished in the Current Directions in Psychological Science addresses the many problems with the lizard brain model, and urges people to “abandon this mistaken view of human brains.”

From the perspective of evolutionary biology (not my expertise) the authors state the triune brain idea is “in contrast to the clear and unanimous agreement on these issues among those studying nervous-system evolution.” From the perspective of evolution, they note three major problems with the triunebrain model.

Firstly, it implies evolution is a linear progression with one organism evolving into the next: lizards > mice > monkeys > humansAnd at the same time more complex layers of brain are added on top of pre-existing layers.

This is wrong! Mammals did not evolve from reptiles. Mammals and reptiles share a common fish- like ancestor.

“... the correct view of evolution is that animals radiated from common ancestors. Within these radiations, complex nervous systems and sophisticated cognitive abilities evolved independently many times.”

Secondly, the cerebral cortex is not unique to mammals because reptiles, fish and birds have a cerebral cortex too.

Thirdly, the brain did not evolve with more sophisticated layers built over simpler layers.“The notion of layers added to existing structures across evolutionary time as species became more complex is simply incorrect.”

Emotions are not pre-wired, we construct them

From the perspective of neuroscience, the reptilian brain analogy completely falls apart when we consider our up-to-date understanding of the neurobiology of emotions and behaviour.

In 2020, most neuroscientists no longer support the notion that our lives are ruled by hard-wired instincts deployed automatically in response to particular triggers with certain emotions accompanied by a specific facial expression and physical sensation.

This so-called ‘classical view’ of emotions is falling out of favour as we learn more about how the brain works, and more about how humans learn and even more about consciousness. Instead, evidence points towards a theory of ‘constructed emotion’. This theory proposes that a set of emotions are not pre-programmed into our brains. Instead, various ‘ingredients’ are processed by entire brain networks to ‘construct’ consciously experienced feelings in the moment.

The ingredients of emotions

The ingredients of emotions include:

  • the physiological sensations we feel in our body

  • the situation we’re in

  • the people we’re with

  • our memories and personal experiences

  • the language we’ve learned to describe our conscious feelings.

Neuroscientist Lisa Feldman Barrett states,

“An emotion is your brain’s creation of what your bodily sensations mean, in relation to whatis going on around you in the world”.

Joseph LeDoux has proposed a similar theory of emotion construction based on decades of studying that most ‘primal’ of emotions: fear. He states the conscious feeling of fear is what emerges when certain kinds of nonconscious ‘ingredients’ coalesce and are cognitively interpreted or ‘noticed’.

“Emotions like fear are often said to have been inherited from animal ancestors... Fear and anxiety are not biologically wired. They do not erupt from a brain circuit in a pre-packaged way as a fully formed conscious experience.”

Evolution has done the heavy lifting and we possess swift acting threat-detection circuits (including the amygdala and hypothalamus). But learning and memory, language and culture are additional raw ingredients that are also added to the mix tocreate conscious feelings of fear and anxiety.

There is no hard-wired lizard-brain ‘fear’ circuit.

As LeDoux points out we can be feel threatened by a huge variety of events: predators, lack of food or water can cause us to fear starvation or dehydration; extreme low temperatures can cause fear of death by hypothermia; cancer diagnoses scares us all; public health officials used to fear a global outbreak of a contagious virus, many of us worry about political instability, economic loss, social abuse, and existential concerns. (That lizard must be very evolved!)

For those of you who want to explore these ideas further, here’s a useful explainer if you’d like to read more on LeDoux fear research. And a meta-analysis testing Barrett’s hypothesis.

We label emotions based on context

It certainly seems like emotions are quite sudden, subconscious experiences that aredeployed automatically. But if you stop to think about this carefully you’ll realise how often we might experience an emotion that is inappropriate or misattributed simply because of the situation we’re in.

For example, we often use the phrase ‘fight or flight’ to describe activation of the sympathetic nervous system (SNS) whereby release of noradrenaline from nerve endings and directly into the bloodstream increases heart rate and breathing and directs blood to the large leg muscles. (And of course the reptilian brain is often said to respond to and trigger ‘fight or flight’).

Contrary to the romanticised version of events, Mother Nature did not evolve the SNS exclusively to save ancient cave-dwelling humans from sabre-tooth tigers. The SNS evolved to meet the body’s energy demands to all matter ofthreats and challenges and opportunities.

Consider a lion, an antelope, and an athlete. The lion chasing the antelope, the antelope itself, and the athlete running a 400m race all experience SNS activation that enables them to run fast and meet their particular challenge.

But who do we attribute ‘fear’ to? Only to the antelope, not the athlete. Certainly not the lion. When in fact, the same physiological ingredient (SNS activation) is involved, but in slightly different contexts, which leads us to use very different ’emotion’ words to describe how the lion, antelope or athlete might be feeling.

See how we intuitively know that context matters.

Name it to tame it.

If you’re a therapist or coach you’ll know the ability to recognise and develop vocabulary is necessary to analyse and reflect on emotional patterns.

Consider the worlds of feeling captured in the following words: mad, meek, mean,miserable, malevolent, marvellous, manipulated, manipulative, misunderstood, mischievous, mopey, melodramatic, moody, melancholy, mirthful, moved, morose, or manic?

The brain doesn’t contain a pre-packed hard-wired repository of emotions in this list. They’re all concepts we gradually learn about as we grow up. We learn the appropriate vocabulary to describe how we feel relevant to a particular situation or social context.

Little children lack specific emotion words. So a three-year old watching an older sibling eating ice cream in front of them will most likely feel very sad. A 13-year-old, with their a decade of experiences and a larger vocabulary, would perhaps experience something like mild envy when they realise the ice cream was given to their sibling by a teacher for winning a spelling bee.

Learning new emotion words isn’t limited to childhood.

As Barrett points out, there was once no English word for the feeling of pleasure at someone else’s misfortune till the German’s donated us “schadenfreude”. When we learn a new expression or description, we’re more likely to recognise and experience that emotion in the future. Schadenfreude is not a hard-wired emotion deployed only by German speakers when someone they dislike screws up.

Tim Lomas at the University of East London has taken the notion of learning new words to describe emotions to the next level in his Positive Lexicography Project. He gathers words of “precise emotional experiences that are neglected by the English language”. Do you recognise these nuanced emotional experiences?

  • Desbundar (Portuguese) – to shed one’s inhibitions in having fun.

  • Gigil (Tagalog) – the irresistible urge to pinch or squeeze someone because they are loved or cherished.

  • Natsukashii (Japanese) – a nostalgic longing for the past, with happiness for the fond memory, yet sadness that it is no longer.

  • Yuan bei (Chinese) – a sense of complete and perfect accomplishment.

  • Sukha (Sanskrit) – genuine lasting happiness independent of circumstances.

I’ve been using the Dutch word “melig” for years after learning it from friends on a holiday in the Netherlands. It describes that delicious slightly sleepy state when everything is hilarious or silly and you giggle at anything.

Barratt and other researchers have compiled evidence that if you increase your emotional vocabulary or ‘emotional granularity’, you can influence future emotional experiences.

In this way, expanding your emotion vocabulary is a bit like owning a mental wellbeing thesaurus, giving you a strong sense of agency over the situations and responses you experience.

Would any of this be possible if the lizard brain was in charge?

Does it matter if we use the ‘reptilian brain’?


We are not born with hard-wired pre-packaged emotions emerging from a lizard brain. The human brain is not a tripartite-series of separate complexes. We are not at the mercy of our lizard brain when we experience threat. We’ve established that.

But does it matter if we use an (incorrect) analogy of how the brain works?

A coach educator commented on my Instagram recently that it doesn’t matter, she said, “I teach triune brain concept to my students with a caveat that the theory is outdated and neurobiologists can’t agree on evolution point and on borders between ‘brains’. However, for coaches, it’s an easy concept to grasp and understand.”

I personally wouldn’t teach a concept that was flat-out wrong. And I like to give a littlemore credence to my students’ ability to grasp basic neuroscience concepts! Casario and colleges ask the same question: “Does it matter if psychologists have an incorrect understanding of neural evolution?”

And they answer their own question with the statement: “We are scientists. We are supposed to care about true states of the world even in the absence of practical consequences.” If you’re a scientist I’m sure you agree! If you’re not a scientist, but you ‘use’ brain science to explain behaviour, or employ the technique of psychoeducation in your work, please do not be seduced (norseduce others) with the allure of the neuroscience explanation. Especially one that’s plain wrong and removes emotional agency from your client.

My problem with the reptilian brain analogy is that it implies human behaviour is driven by first and foremost by fear. And that the reptilian brain overpowers the ability to have calm and rational thought.

The model side-steps any discussion of the enormous diversity of emotional experiences we are capable of and which deeply move us: passionate love, envy, desire, awe, contentment, grief, exhilaration, tenderness. And it removes any sense of agency we have for new emotional experiences in the future.

As Barrett points out in her book,

“Humans are not at the mercy of mythical emotion circuits buried deep in the animalistic parts of our highly evolved brain: we are architects of our own experience.”

When you teach people how emotions are created from various ‘ingredients’ you are doing more than communicating, you are creating reality. You are teaching tools for making meaning of body sensations and how to act on them, to communicate with nuance how they feel. This is an essential life skill!

Alternatives to conversations about the triune brain

Instead of defaulting to a conversation about ‘the reptilian brain’ here’s a few neuroscientifically and evolutionary correct stories or explanations to use.

In the spirit of the positive lexicography project, if you have any other useful explanations of human brains or behaviour that you use (that don’t involve reptiles) leave a comment below.


  • If you’re describing brain anatomy, and want to distinguish the amygdala from the hypothalamus from the brainstem I recommend you use this online 3D brain anatomy tool.


  • “Emotions are made up of ingredients such as your bodily sensations, your life experiences and expectations, the people you’re with, the situation you’rein. What ingredients have helped build the emotion you’re feeling at the moment?”

  • “We the architects of our thinking and behaviour, we are also the architect of our emotions.”

  • “Emotions are not reactions to the world. You are not a passive receiver of sensory input but an active constructor of your emotions. From sensory input and past experience, your brain constructs meaning and prescribes action.”

  • “You can practice emotions in advance of a situation by teaching your brain the most useful way to respond in a situation. Actors do this all the time. The emotions they feel on stage are real because they rehearsed their creation.”

  • “Worry is repeating a thought over and over again. You are practicing that thought, and with practice it gets easier to experience the thought over time. You can practice positive thoughts and emotions instead."


  • “Just like a painter learns to see fine distinctions in colours, or a wine connoisseur develops their palette to experience tastes non-experts can’ttaste, you can practice naming emotions. With practice, you can become an expert namer and categoriser of emotions.”

  • “Emotions such as sadness come in many shades of blue. Let’s come up with five words to describe how you feel today.”


  • Try to deconstruct the ingredients of your emotions especially your body sensations. e.g a fast-beating heart doesn’t necessarily mean your brain has detected a threat or there is something to fear. Perhaps your heart is beating faster because you’re excited, or you’re getting ready to exercise.

  • If someone is scared of, say, a spider, ask them to describe the spider using as many emotion words as possible, e.g. “The spider in front of me makes me feel disgusting, nerve-wracking and jittery but is kind of intriguing.”

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