Does a Bigger Brain Make You Smarter?

It’s tempting to think that the bigger the brain, the smarter the person—but the answer isn’t that simple. Let’s dive into the science of brains, intelligence, and whether size really matters.

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Episode Transcript

I Wonder Podcast (00:03):
Hey there, curious minds, welcome to
another episode of I Wonder, theshow where we explore the
questions you've been wonderingabout.
Today's question comes fromJason.
Jason asked "does a biggerbrain make you smarter?
" What a brain question, Jason.
It's tempting to think that thebigger the brain, the smarter

(00:25):
the person, but the answer isn'tthat simple.
Let's dive into the science ofbrains, intelligence and whether
size really matters.

(00:51):
How big are human brains?
The average adult human brainweighs about three pounds and is
roughly the size of twoclenched fists.
It contains around 86 billionneurons, which are the cells
that carry information and allowus to think, feel and act.

(01:13):
But here's the twist.
Humans don't have the biggestbrains in the animal kingdom.
In fact, sperm whales havebrains that weigh about 17
pounds and elephants' brains areabout 10 pounds.
If brain size alone determinedintelligence, whales and

(01:34):
elephants would be far smarterthan humans.
But that's not the case.
The secret to intelligence isn'tbrain size.
It's how efficiently thebrain's neurons connect and
communicate.
Think of your brain as asupercomputer.
It's not just about how big thehardware is, but how fast and

(01:59):
organized the processing systemworks.
Neurons in your brain formtrillions of connections, called
synapses, which allowinformation to flow.
The more connected andefficient these networks are,
the better your brain can solveproblems adapt and learn new
skills.
A lbert Einstein, one of themost brilliant minds in history,

(02:26):
had a brain that was slightlysmaller than average.
What made him exceptionalwasn't the size of his brain,
but the unique structure anddensity of certain areas,
particularly those involved inmathematical reasoning and

(02:47):
imagination.
This shows that the quality ofyour brain's wiring matters far
more than its size.
Okay, but what about brain sizein animals?
Let's explore why some animalshave such massive brains.
Whales and elephants have largebrains primarily because they

(03:08):
need to control their enormousbodies bigger one-third the body
requires more neurons to managemovement, sensory input and
organ function.
Humans, on the other hand,actually have a much bigger
brain-to-body ratio, whichmeasures the size of the brain
compared to the overall bodysize.

(03:30):
This ratio is one of thereasons humans are capable of
advanced thinking, creativityand problem solving.
Even within the animal kingdom,brain organization plays a
bigger role than size.
For example, crows and parrotshave relatively small brains.
They're incredibly intelligent,capable of solving puzzles and

(03:54):
even using tools.
Their brains are densely packedwith neurons, making them
highly efficient.
Does brain size matter inevolution?
While brain size isn't the solemeasure of intelligence, it has
played a, like Australopithecus, had brains about 1 third the

(04:18):
size of ours today.
Over millions of years, thehuman brain grew larger relative
to body size, allowing for morecomplex thinking, language and
creativity.
However, what truly set humansapart wasn't just the size of
our brains, but the developmentof specific - about like the

(04:41):
prefrontal cortex, which handlesplanning, decision-making and
problem-solving.
Interestingly, as our brainsgrew, they became more
energy-efficient.
Your brain uses about 20% ofyour body's energy, even though
it makes up only 2% of yourweight.

(05:02):
Makes up only 2% of your weight.
That's like having a small butincredibly powerful engine that
requires a lot of fuel to run.
How fast does the brain grow?
The brain grows remarkably fast, especially during the first

(05:24):
few years of life.
By the time you're born, yourbrain already contains almost
all the neurons it will everhave about 86 billion.
In the first year after as youlearn to move, communicate and

(05:45):
explore the world.
By age three, your brain isabout 80% of its adult size.
Even though the brain reachesits full size by your mid-20s.
It continues developing andadapting throughout your life.
The last part to mature is thatprefrontal cortex we mentioned,
which does explain whyteenagers sometimes struggle

(06:08):
with impulse control anddecision making.
It's all part of your braingrowing and really fine-tuning
itself.
Do we lose neurons as we age?
Yes, but it's not as scary asit sounds.
Starting in your 20s, certainparts of the brain, like those

(06:30):
involved in memory, graduallylose neurons.
However, the brain isincredibly adaptable through a
process called neuroplasticity.
Even as neurons decrease, thebrain can strengthen existing
connections and form new ones tomaintain its efficiency.
Some areas of the brain, likethe hippocampus, which is the

(06:53):
area responsible for memory, caneven produce new neurons
throughout life.
Responsible for memory can evenproduce new neurons throughout
life.
This process is calledneurogenesis and it shows that
staying mentally active, eatinga healthy diet and exercising
can help keep your brain sharpas you get older.
Here's some fun facts aboutbrains.
Did you know your braingenerates enough electricity to

(07:17):
power a small light bulb?
It's true, your neuronscommunicate using tiny
electrical signals and whenbillions of them fire at once,
they produce measurable energy.
Here's another cool fact yourbrain is about 60% fat, making
it one of the fattiest organs inyour body.

(07:39):
That fat plays a crucial rolein insulating neurons, helping
them send signals quickly.
Brains also have an amazingability to change and adapt
throughout life.
This flexibility, known asneuroplasticity, allows you to
learn new skills, recover frominjuries and even form new

(08:02):
habits.
So, to answer Jason's question,does a bigger brain make you
smarter?
Not really.
While brain size plays a rolein evolution, intelligence
depends much more on how thebrain's neurons connect and

(08:25):
communicate.
It's not about how big yourbrain is, it's about how well it
works.
Thanks again to Jason for sucha thoughtful question and
remember, if you have a questionyou're curious about, submit it
on our website, iwonderpodcast.
com, and we might just featureit in our next episode of I

(08:48):
Wonder.
Until next time, stay curiousand keep wondering in.