The Evolution of Intelligence
Story No. 3: When Electricity Began to Flow Through the Body

Shariq Ali
Valueversity

In the previous story, we saw that the cells of multicellular organisms communicated with one another through chemical messages. This system worked, but it had one major limitation: it was very slow.
As organisms grew larger, this problem became increasingly obvious. If danger appeared at one end of the body, it could take a considerable amount of time for the information to reach the other end.

Evolution needed a better solution.
Nature came up with a remarkable answer: neurons, or nerve cells.

These were specialized cells capable of transmitting not only chemical messages but also electrical signals. For the first time in the history of life, information no longer seemed to crawl slowly through the body—it began to race.
A simple example of this can be seen in the Hydra.

Hydra is a tiny aquatic animal found in ponds and lakes. It has no brain, yet its body contains a network of nerve cells. If any part of its body is touched, it responds almost instantly by contracting itself.

This was a major evolutionary breakthrough.

For the first time, living organisms could react rapidly to changes in their environment. Chasing food, escaping predators, and coordinating body movements became much easier and more effective than before.
In this way, the nervous system connected different parts of the body and created a true information highway. Millions of cells were no longer working independently; they had become part of a unified communication system.

But the journey of evolution was far from over.
Nerve cells had appeared, yet a new question soon emerged. If thousands of nerve cells existed within a body, who would organize the information they carried? Who would make decisions? Who would gather different signals in one place and interpret their meaning?

This question pushed evolution toward its next great revolution:

The emergence of central nervous centers and the first primitive brains.

That story will be told in the next episode.

Stay with us on this fascinating journey through the evolution of intelligence.