Why the insect brain is so incredible - Anna Stöckl

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The human brain is one of the most sophisticated organs in the world, a supercomputer made of billions of neurons that control all of our senses, thoughts, and actions. But there was something Charles Darwin found even more impressive: the brain of an ant, which he called “one of the most marvelous atoms of matter in the world.” Anna Stöckl takes us inside the tiny but mighty insect brain.

Lesson by Anna Stöckl, animation by Studio Gal Shkedi.

The human brain is one of the most
sophisticated organs in the world,

a supercomputer made of billions
of neurons

that processes and controls all
of our senses, thoughts, and actions.

But there was something Charles Darwin
found even more impressive:

the brain of an ant,

which he called one of the most
marvelous atoms of matter in the world.

If you find it hard to believe that
something so tiny

could have a complex brain,

you're not alone.

In his project to classify and describe
all living things,

Swedish naturalist Carl Linnaeus
assumed insects had no brains at all.

He was wrong, but understandably so.

Insect brains are not only miniscule,

but in many respects,
they function differently than our own.

One of the most noticeable differences

is that an insect that loses its head
can still walk,

scratch itself,

breathe,

and even fly.

This is because while our nervous system
works like a monarchy,

with the brain calling the shots,

the insect nervous system works
more like a decentralized federation.

Many insect activities,
like walking or breathing,

are coordinated by clusters of neurons,
also known as ganglia,

along their bodies.

Together with the brain, these local
ganglia form the insect nervous system.

While an insect can do a lot with just
its local ganglia,

the brain is still crucial
for its survival.

An insect's brain lets it perceive
the world through sight and smell.

It also chooses suitable mates,

remembers locations of food sources
and hives,

regulates communication,

and even coordinates navigation
over huge distances.

And this vast diversity of behaviors

is controlled by an organ
the size of the head of a pin,

with less than one million neurons,

compared to our 86 billion.

But even though the insect brain
is organized very differently from ours,

there are some striking similarities.

For example, most insects have
smell detectors on their antennae,

similar to those found in human noses.

And our primary olfactory brain regions
look and function rather similarly,

with clusters of neurons activated
and deactivated in precise timing

to code for specific scents.

Scientists have been astonished
by these similarities

because insects and humans are not
very closely related.

In fact, our last common ancestor
was a simple worm-like creature

that lived more than 500 million
years ago.

So how did we end up
with such similar brain structures

when our evolution took almost
entirely different paths?

Scientists call this phenomenon
convergent evolution.

It's the same principle behind birds,
bats, and bees separately evolving wings.

Similar selective pressures can cause
natural selection

to favor the same evolutionary strategy

in species with vastly different
evolutionary pasts.

By studying the comparison between
insect and human brains,

scientists can thus understand which of
our brain functions are unique,

and which are general solutions
to evolutionary problems.

But this is not the only reason scientists
are fascinated by insect brains.

Their small size and simplicity makes it
easier to understand

exactly how neurons work together
in the brain.

This is also valuable for engineers,

who study the insect brain to help design
control systems

for everything from self-flying airplanes
to tiny search-and-rescue roach bots.

So, size and complexity are not always
the most impressive things.

The next time you try to swat a fly,

take a moment to marvel at the efficiency
of its tiny nervous system

as it outsmarts your fancy brain.