Rethinking the reptilian brain.

lizard triune brain myth

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.


Because the concept is widely discredited by neuroscientists and evolutionary biologists: the model is out-of-date and not based on contemporary science.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 it’s used variously to label the:

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 a rather 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 Inside’ published 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 triune brain model.

Firstly, it implies evolution is a linear progression with one organism evolving into the next:

lizards >  mice >  monkeys > humans

And 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 what is 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 to create 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!)

Here’s a useful explainer if you’d like to read more on LeDoux fear research.

We label emotions based on context

It certainly seems like emotions are quite sudden, subconscious experiences that are deployed 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 of threats 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.

Words for emotions you never knew you had

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 3-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?

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 little more 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 (nor seduce 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.

Brain anatomy

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

What are emotions

  • “Emotions are made up of ingredients such as your bodily sensations, your life experiences and expectations, the people you’re with, the situation you’re in. 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. ”

Emotional regulation

  • “Just like a painter learns to see fine distinctions in colours, or a wine connoisseur develops their palette to experience tastes non-experts can’t taste, 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.”

Fear & autonomic responses

  • 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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  1. Sigrid Loos on June 25, 2020 at 6:38 am

    This is a fascinating article. Thank you so much for these insights!

  2. Jeri on June 25, 2020 at 6:47 am

    Love this! After completing the academy and getting Caught up in finding alternatives available. This is helpful!!

  3. Pam McIntosh on June 25, 2020 at 9:37 am

    I find this really interesting especially in light of listening to a you tube video on the Science of Compassion by Stephen Porges. I was struggling with some of the things he was saying in light of what I have learned in your course (2018 alumni). I couldn’t quite put my finger on why, but after reading this article…you totally nailed it for me. Thanks heaps for sharing this….very timely. I am doing a Counselling and Neuroscience course and Trauma Informed Practice – there is a lot of emphasis on the Polyvagal Theory in supporting clients health/recovery.

  4. Rod Irwin on June 25, 2020 at 11:12 am

    Hi Sarah,
    Love this!
    The Shiva-Sutra describes a state of being “wonderstruck” with life, awareness, and reality. Called vismayo, this state describes how a person experiences waking life, sleep, dream, and our material reality as one. Awesome!

  5. Rena on June 25, 2020 at 11:28 am

    Thanks for this! What is the current consensus on the function of our threat-scanning brain equipment? Is it accepted that humans have instinctual wiring that scans for danger and sends us into fight/flight mode when a threat is perceived? And that using techniques like deep breathing can return us to a calm, PNS state? I no longer teach triune brain, but I still teach methods for regulating first-responder stress signals. I want to make sure I am not mis-peaking!

    • Sarah McKay on June 25, 2020 at 11:43 am

      This is correct. Deep breathing definitely returns us to a calmer state. We regulate our breathing rate using our phrenic nerve (a motor nerve that innervates the diaphragm) and the slower breathing somehow signals to the parasympathetic nervous system to activate and ‘calm’ down. There’s still a bit of a gap in our neuro-knowledge how exactly the slower breathing activates the PNS. (Important to note here the PNS doesn’t slow breathing, we consciously do that via the phrenic nerve).
      Also, it looks like there’s a difference between this ‘subconscious’ threat detectiion + SNS response and our ‘conscious’ experience of the emotion ‘fear’. Like I say, we need a few more ‘ingredients’ that simply SNS activated to cause the emotion of fear. We can also ‘feel scared’ but not necessarily have a physical response. LeDoux talks a lot about this subtle but super important difference.

  6. Diana on June 25, 2020 at 8:58 pm

    Dear Sarah, I’m one of your alumnae at the Neuroscience Academy and I LOVE THIS ARTICLE. So explanative, clear, enlightening! THANK YOU.
    I still meet people that teach the triune brain and also the famous “Conversational Intelligence” model of Judith Glaser is basically rooted in this vision of the brain with a reptilian part. Problem is: although I learnt with you some years ago that this model was outdated I wasn’t able to articulate enough effectively an alternative that could be useful for my clients to enhance the responsibility they have in taking care of our emotions and cultivate intentionally how to respond to the most discomforting ones. NOW I HAVE IT! The last part of this article especially lays out with details how to face a conversation around this. Problem is: meanwhile I used Judith Glaser’s 5-parts brain model!!! So have can I amend that with my coachees, my corporate clients where I train people on leadership etc.? It makes me uncomfortable to say “You know what? there’s a better explanation that I know ill propose you!”. Has anybody handled that and can give me a hint? Thank you!

  7. peter ffrench on June 25, 2020 at 9:27 pm

    Thanks Sarah
    I’ve been looking for a succinct summary of this .. really appreciate it

  8. Radha on June 26, 2020 at 3:32 am

    I love the article and how descriptive it is yet simple to understand.

    I have been taught this model and I talk about it too but I always felt there were loose ends that didn’t match up somehow.
    I do have a question – I read somewhere that we are wired strongly for negative emotions and which is why it is easier for us to feel negative or bring up bad memories than good ones which have to be consciously thought about. That this is for our survival as the prehistoric man would remember his negative experiences of being attacked by saber tooth more clearly so he would be alert . Is this true ?

  9. Kerry Gibbett on June 26, 2020 at 4:28 pm

    This is the most eloquently written pieces of work on emotions that I have ever read. Sarah, you’ve nailed it! So enjoyable to read. So powerful and far reaching ramifications.
    Thank you.

  10. Judy Hilton on June 26, 2020 at 5:18 pm

    Great post thank you Sarah. I have been reading Lisa’s book and challenging myself to give up the old triune brain model and Eckman/ Mayer Salovey models of EI and face recognition. You make a good point. Just because a model is convenient and easy doesn’t make it accurate.

    • Sarah McKay on June 26, 2020 at 5:55 pm

      I don’t think there is anything wrong with using a simple model to explain something super complex. But in this case the reptilian brain has taken a mind of its own (hah!) and is taught as neuroscience fact. Delighted that you’ve read Lisa’s book and found it useful.

  11. John Quinn on June 27, 2020 at 12:00 am

    This has turned my world upside down. I’d always been troubled by the reptilian brain model but had taken on some of its assumptions. I’ll have to spend some time reworking my understanding to fit with what your saying. We build our own emotional responses and can rebuild them … emotional plasticity? Not fixed circuitry

    • Sarah McKay on July 4, 2020 at 12:32 pm

      I hope upside down in a good way!?

  12. Susan C on June 28, 2020 at 1:02 am

    Thank you for this clear explanation.

    Models like the ‘triune brain’ are appealing, they seem to cut through, bypass? the complexity that is our brain. In doing so, the brain is reduced to its parts and the whole can get lost.

    As a decades old educator I have been through education’s many attempts to simplify or reduce learning to parts. For example, the idea of ‘learning styles’ (never proven empirically) posits that learners can be categorized as ‘visual’, ‘auditory’ or ‘kinetic’ and that teaching should play to the ‘strength’ of the learner. The theory misses the fact that it takes a whole brain to learn. Deep, rich mental processing does not ‘have a chance’ with such theories.

    From Eric Kandal (Reductionism in Art and Brain Science)
    * “While our eyes do provide information we need to act, they do not present our brain with a finished product”.

    * and “…while brain structures are separable conceptually at every level of organization, they are related to one another anatomically and functionally, and therefore cannot be separated physically”.

  13. Debbie Green on July 4, 2020 at 1:37 am

    Thank you for this Sarah – great explanation and it made perfect sense. I can now adapt my language with working with my coaches as it gives a much better understanding of what is going on for them at that moment and can now “drop” the term reptilian brain – thank you.

    • Sarah McKay on July 4, 2020 at 12:31 pm

      Delighted to hear this 🙂

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About Dr Sarah

I’m an Oxford University-educated neuroscientist, presenter of ABC Catalyst, director of The Neuroscience Academy, and author of The Women's Brain Book. The neuroscience of health, hormones and happiness.

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