WEBVTT

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

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a supercomputer made of billions
of neurons

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

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But there was something Charles Darwin
found even more impressive:

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the brain of an ant,

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

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If you find it hard to believe that
something so tiny

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could have a complex brain,

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you're not alone.

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In his project to classify and describe
all living things,

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

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He was wrong, but understandably so.

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Insect brains are not only miniscule,

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

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One of the most noticeable differences

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

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scratch itself,

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breathe,

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and even fly.

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

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with the brain calling the shots,

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the insect nervous system works
more like a decentralized federation.

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Many insect activities,
like walking or breathing,

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

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along their bodies.

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

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

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the brain is still crucial 
for its survival.

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

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It also chooses suitable mates,

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remembers locations of food sources
and hives,

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regulates communication,

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and even coordinates navigation
over huge distances.

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And this vast diversity of behaviors

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

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with less than one million neurons,

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compared to our 86 billion.

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

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there are some striking similarities.

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

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similar to those found in human noses.

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

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with clusters of neurons activated
and deactivated in precise timing

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to code for specific scents.

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Scientists have been astonished
by these similarities

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because insects and humans are not
very closely related.

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

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that lived more than 500 million
years ago.

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So how did we end up
with such similar brain structures

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when our evolution took almost
entirely different paths?

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Scientists call this phenomenon
convergent evolution.

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

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Similar selective pressures can cause
natural selection

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to favor the same evolutionary strategy

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in species with vastly different 
evolutionary pasts.

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By studying the comparison between
insect and human brains,

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

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and which are general solutions 
to evolutionary problems.

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

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Their small size and simplicity makes it 
easier to understand

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exactly how neurons work together 
in the brain.

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This is also valuable for engineers,

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who study the insect brain to help design
control systems

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

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

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The next time you try to swat a fly,

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

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as it outsmarts your fancy brain.