top of page

How did we become so complicated?

(Evolution of the nervous system)


Neuroletter, Volume 2 Issue 1



Keeping up with the plethora of thoughts, feelings,

And perspectives- the game is hectic.

But there used to be a time when things were simple

When even signaling wasn’t that electric.

(Protozoa used non-electrical signaling for motility)


Single-celled eukaryotes probably initiated it all

In physics, cells have always had great reliance.

But electricity, is an elusive game, for a long time,

Potentials were propagated through calcium ions.

(Single celled eukaryotes used Ca2+ ions for signaling instead of Na+, and this was adopted in multicellular organisms)


The neuron was created, and it refused to be alone;

Not communicating, would make it go berserk.

The neuronal agenda was to connect and “talk,

Thus, giving rise to the neural networks.

(Neurons function by the networks and connections they create)


Tracing the nervous system has been a bumpy ride,

With conundrums reaching their absolute heights.

Some say that in the evolutionary path,

The nervous system may have evolved twice

(Did neurons evolve twice?)


The (possibly) vapid common ancestor

Caused a dispute in the tree;

One branch gave rise to simple sponges

The other carved the strange Comb jelly

with a slew of neural peptides.


The comb jelly- beautiful and odd;

Had a penchant for swimming against tides. For in a world of chemical messengers, They communicate.


The sponges, lacked the neural affair But they sure served as worthy guardians. All our “complications” today had stemmed from the jellyfish and the bilaterians.


The comb jellies and the jellyfish, simple and luminous,

Sensed and moved through diffused nerve nets.

Even without a central control, they could perceive the environment, And whenever needed, swiftly move away from threats.


The bilateria, and their illustrous successors

It started off simple-a tubelike body it could

maintain, But the nerve cord that ran from front to end

Ended in a large ganglion, termed as “brain”.


Author: Sumedha Sengupta


Recent Posts

See All
bottom of page