No, You Don’t Have a “Reptilian Brain”

[ ♪ Intro ] You might have come across articles like How
to Make Friends Using Your Reptilian Brain or Overcome Your Reptile Brain to Lose Weight. And if they seemed to make a lot of sense… Well, I’m sorry to be a spoilsport, but the idea that humans have a primitive reptile brain deep down there somewhere is largely
false. It is based on a tiny bit of truth, though,
which might explain why it’s stuck around for half a century. This ‘reptile brain’ nonsense started
in the sixties when neuroscientist Paul MacLean proposed the Triune Brain Theory. He was trying to explain how animal brains
evolved and why some animals, like us, could reason or plan but others couldn’t. MacLean thought that these more complex abilities
came from extra brain layers added on top of a primitive, instinctive brain base, like
a juicy dumpling is wrapped inside a pastry. The brain’s core was called the protoreptilian
complex. Hence, “reptile brain”. And it’s the name MacLean gave to what we
now call the basal ganglia, a group of neurons at the very centre of the brain. As the name suggests, this region supposedly
explained the behavior of reptiles. MacLean thought it was the neural seat of
motor control as well as instinctual behaviors like defending territory. Wrapped around the reptile brain was the paleomammalian
complex or limbic system, which was largely in charge of emotions. And because emotions are important for things
like social relationships, parental care, bonding and empathy, MacLean thought this
system was especially important to early mammals. The final layer to be added on was what MacLean
describes as the neomammalian complex, a.k.a. the neocortex, which is the 6-layered tissue
that makes up the majority of the folded, “brainy”-looking part of our brains called
the cerebral cortex. This, which is much bigger in “higher”
mammals like us and our primate relatives, is what he thought gives us language, reason
and conscious perception of the outside world. And according to this theory, each of these
layers acts as a separate quote “brain”. So when you get angry and lash out at a potential
rival, that’s your reptile brain taking over, but when you ponder the great wonders
of the world, your neomammalian brain is in charge. Which is why some pop-psychology articles
talk about reigning in your reptilian brain, though that’s not really what MacLean was
going for. In some ways, the Triune Brain Theory is kind
of true, but it’s also pretty wrong. MacLean was kind of right that different parts
of the brain have somewhat different tasks, but his groupings weren’t perfect. Those quote “reptilian” basal ganglia
do help us form habits, and they play a big role in controlling voluntary movements. But they’re also involved in emotions and
executive functions like self control. For example one part, the nucleus accumbens,
is a big player in the brain’s reward circuit. As for the limbic system, that paleomammalian
part, it is heavily involved in emotion and bonding, thanks largely to a structure called
the amygdala. But the term “limbic system” is kind of
falling out of favor because neuroscientists can’t really agree what’s actually in
it. Some neuroscientists consider the orbitofrontal
cortex, the part of the brain that helps make decisions, to be in the limbic system, too,
because it’s tightly connected to other parts of it. Or they use a more encompassing term, the
paralimbic system, instead. Others just stick to functional networks within
the entire cerebral cortex, which includes both the limbic system and that neomammalian
neocortex. Speaking of which, MacLean was right that
the neocortex is a big part of our reasoning, speech and cognitive abilities, but as the
majority of the cerebral cortex, it’s kind of got its fingers in all the neural pies. And it’s not required for intelligence. Octopus can perform some really tricky cognitive
tasks like remembering how to get out of a maze without a shred of neocortex. Also, MacLean’s names for these so-called
brains aren’t great either because they don’t really have anything to do with the
animals they’re named after. That ‘reptile brain’ didn’t first appear
in reptiles, and the limbic system isn’t unique to mammals. In fact, most animals with backbones, including
fish and amphibians, have basal ganglia and a limbic system. And “lower” mammals like mice do have
a neocortex. There’s even evidence that other animals
have a neocortex of sorts. Their brains contain the same types of cells
as the ones in our neocortex, they just aren’t arranged in 6 layers. That might explain how birds, which are actually
reptiles, care for their young or have linguistic abilities. What differs between brains isn’t who has
what so much as their relative size and shape. And it’s not even fair to say that these
regions are most developed in those groups of animals. While it’s true that our neocortex is a
lot bigger than a mouse’s, even accounting for body size, some of the structures in primate
basal ganglia and limbic systems are also larger and more complex. So they aren’t just hold overs from our
more primitive ancestors. But perhaps the biggest problem with the Triune
Brain Theory is the idea that these different “brains” work independently, or even linearly. We don’t have three separate brains, we
have one big coordinated one. Brain activity underlying a behavior may start
in one specific area, but it’ll soon spread as other parts help out, an idea known as
distributive processing. And that’s how that neocortex has its fingers
in all the pies. Let’s say some really attractive person
starts hitting on your partner, and that makes you livid. Those feelings of rage might start with activity
in the amygdala, a part of that “limbic system”. But then other parts of the cerebral cortex
including neocortical areas can either increase or decrease the probability that you’ll
flip out based on cues from the environment. And the basal ganglia, particularly the nucleus
accumbens, play a key role in deciding what you actually do with all your anger by integrating
information from both the neocortex and the limbic system. So your jealous rage isn’t your territorial,
protoreptilian complex taking control, it’s multiple parts of your brain working in concert. To cut MacLean some slack though, his theory
reflected the knowledge neuroscientists had at the time. Like many scientific theories, it evolved
and became outdated as scientists got new information through neuroimaging and behavior studies. So, although MacLean was on the right track
in terms of understanding how brain structure relates to function, he got a lot wrong when
it comes to how those structures work together and the evolution of animal brains. And ultimately, that means you don’t need
to worry about trying to control your reptilian brain because it doesn’t exist! Thanks for watching this episode of SciShow! And if you like learning about brains and
how they work, you might want to check out our sister channel SciShow Psych. And while reigning in your inner reptile might
not be the way to keep your emotions in check, you can learn more about how to actually do
that in our Psych episode on controlling emotions. [ ♪ Outro ]

53 thoughts on “No, You Don’t Have a “Reptilian Brain”

  1. Man i live the SciShow.
    It's actually a great relieve to see that there are not only superstitious morons around the internet, but also enlightened and rational people.

  2. You guys are off the mark. You've hinged the entire video around a mistaken hypothesis, but at this point the term is more about psychology than brain physiology.
    While the origin of the term is a mistaken interpretation, "lizard brain" is now just a euphemism for human behaviors that can be traced back hundreds of millions of years. There's a thing called evolutionary psychology, which seeks to identify which human psychological traits are evolved adaptations. Those traits that were developed in our ancestors from 600 million or whatever years ago can be considered our "lizard brain".

  3. It is curious how a video from a channel that has 5.5 million subscribers only has 178 thousand views. Am I using my reptile brain now?

  4. If animals have the necessary neurobiological substrates for consciousness and emotions, then why don't they have rights? I mean, surely, there are some infant children and mentally handicapped humans who have less sentients and intelligence than animals. Pigs are as smart as 3 and a half-year-olds… But we make them into bacon 🤔.

    If we grant basic rights to mentally handicapped people, then why not animals?

  5. Neomammalian Cortex for hoomans.
    Paleomammalian Complex for mammals.
    Protoreptilian Complex for reptiles.
    Rotting peanut for weebs.

  6. I wonder which brain I'm using when I listen to a theorist explain a theory he thinks doesn't exist! Or, better stated, "My GREAT, GREAT, Great,… Grandmother was "NO" chimpanzee! She was a LEMUR!

  7. I prefer my instincts to higher thought. Instincts are so much easier to understand. Have you ever touched insanity? I have. Now, I'mma go pee on the couch.

  8. @scishow So thank you for bringing us back to "we do not know much about the brain", at least he was KIND OF RIGHT and A TINY TRUE! I was thinking religion is on charge of that.
    And relaying only on harvard studies…..puff…I know many harvard "scientists" that I really dont know how they even finish school.

  9. You have lived a comfortable, safe, and protected life. You do not know anything about how savage the real world is. And yet, you run your mouth. The reptilian brain is real, because without it, even your punk ass would die.

  10. I have used my reptilian brain hundreds of times, and it always gets me what I want. Try and explain why this process works so well. You cannot. If you ever meet a Marine in a dark alley, and try to take his money, you will discover just how primitive a trained reptilian brain can be. (You will never recover fully.)

  11. You believe in science fiction which is not lies govern lies an covering up.

    No they may not have a reptillian Brain but their brain is being controlled via telepathic.

    Via pycho tronic weapons.

    By aliens the US military trades alien technology.

    Some may be alien shape shifters.

    They can shape shift their brain physically
    Your body is metaphysicall

    Its not possible to have a reptillian brain
    But it is possible that reptillians can shapeshift metaphysically

    Humans turn into metaphysical aliens.

    Some aliens are us from the future.

  12. This guy is great at explaining, and the graphics really helped. There were lots of really big terms to digest, and lots of nerd-speak, but I was able to completely follow.

  13. The critical faculty decides between acceptable or rejectable knowledge, good r bad food/behaviour, fight/flight etc. This feature is fully and acutely developed in snakes and Paul D. MacLean used this fact to label the part of the brain he theorized dealt with this behaviour in humans. Hence his name R-Complex or Reptilian brain. Now have a look at your world again. All two-isms. + – charge/spin, like/dislike, love/hate keep going…, right/wrong….

    Now the question you need to face is this: Do these two-isms mean I have to see other people as good or bad, enemy or friend? No it doesn't. That f'ing simple. Stop being sh!t to each other.

  14. this sounds like misinformation – The "Reptilian" Brain refers to the "R-Complex" which you do have. This component of your brain is responsible for your survival instincts.

  15. I thought the reptilian brain was due to it having the same shape as a reptiles.
    Hey maybe during our development, a snake got stuck inside our heads, fused genetically and became the spine… 😭

  16. We do still have a reptilian brain. It is right below the limbic system and neocortex. This is what keeps people in repetitive habits.

  17. Humans are not Reptilian Nor is their, Brain any thing to do with Reptilians Reptilians are Cold Blooded as far as you're Brain gos these are made up stories, Humans turning into Reptilians dose not happen those are Clones, with a Demonic Spiritual Entities, Demons within the Clone, who will look human on the outside, but are more sinister from within Nor are these Animals, form or Spiritual Beings you're Family plus they are not from out of Space Aliens, these are Demonic Spiritual Beings Demons there's a big difference in them Alien's come and go, and want to know about Earth Demons want to play tricks on the human race and want to harm you, use and abuse you, they have made Clone's of these Reptilians, stand up and walk like a human but are not human then they Channel the Entity into the Cloned body Evil Twisted and insane, this is what the Elite families in this world have done to fool the masses into believing that these are Aliens from a different planet, these are Cloned bodies with demonic Entities demons inside the Clone, spiritual sinister, dark matter Reptilians are not you're family nor do you, have anything to do with a Reptilians Brain there is no animals Brain contacted to any human Brain as above so below Message Shared 2019/ 11:10/

  18. Yes we do have Reptilian Brian it represents the base cold blooded behavior a desire to control and obsession with hierarchical sturctures

  19. This is completely missing the point. The term "Reptilian Brain" is meant to be a picturous metaphore for the assigned functional parts that are meant to be adressed. Using this term it has never been intended to say that we, as humans, become or would represent or act as a reptile as a life form, if, for instance, all higher brain parts were cut off and only the "Reptilian" ones were left.
    This video is a waste of time obviously made a clever clog.

  20. That whole portion of the brain originally comes from the genetics of those who first created humanity in the beginning, which was the Reptilians from Alpha Draconis on Mars, millions of years ago. 😐

    True story… 🙃

  21. "It does no good whatsoever to ignore the reptilian component of human nature, particularly our ritualistic and hierarchical behaviour. On the contrary, the model may help us understand what human beings are all about."

    –Carl Sagan

  22. Our brain is geared to keep us alive. Its job is not to make us happy, but to keep us dwelling on what is familiar.
    There is a way out!

  23. These three parts of brains obviously aren't clearly delineated and independently carrying out functions separate from other parts of the brain. The brain is one organ. But like the rest of our bodies, our brains absolutely are composed of vestigial parts of our ancestors along with the bits which make them distinctly human. That's what evolution does. We haven't just shed the brains we had when we were other apes, or other types of animal entirely. Human brains are the result of billions of years of evolution. Of course if you cut up a human brain you will see bits which resemble the brains of our ancestors, and that's one reason why we still behave in ways similar to many other forms of life. The fact that other animals can do some of the same things we do without the same type of brain, or that there are things those animals do that we don't, doesn't mean that our brains are not composed of structures which are found in our ancestral species.

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