Dear Max,

Clap your hands. Stomp your feet. Blink your eyes. Every time you move, the brain and body send messages to each other. Under your skin, your nerves stretch out like a network of wires across the body. They help carry these messages from one part of the body to another.

My friend Samantha Gizerian, a neuroscientist at Washington State University, explained how nerves help our bodies work and told me a bit about the first ones.

She says our bodies are made up of lots of different kind of cells, which are kind of like building blocks. Some of these are nerve cells. We would need a microscope to see them, but they are some of the oldest and longest cells in your body. In fact, if we lined up all the nerves a body has, they would stretch for almost 45 miles.

Illustrated, cartoon cat with labcoatWhile the human body has many parts made up of lots cells, some living things are actually just one little cell—an amoeba or a bacteria, for example.

“What I can tell you about the earliest nerves is that when the first groups of single-celled organisms started forming colonies, they weren’t terribly successful because the individual cells in each colony couldn’t talk to each other,” she said.

They didn’t use words to talk to each other like you and me, but they created their own ways to send messages. Gizerian says nerve cells are basically tiny bags of salt water. They have lots of tiny particles called ions floating around on their insides, which makes them like natural batteries, with electrical charges that flow from one place to another.

“Eventually as these colonies developed from individual single cells into organisms made of many cells, some cells became specialized for communication by electricity,” she says. “These were the first nerve cells.”

These days animals have nervous systems that are more complex. After all, you have a lot more nerve cells than an amoeba. Optical nerves in your eyes help you see. Olfactory nerves in your nose and face help you smell things.

It takes a lot of nerves to help the brain and body communicate. In fact, the human body has about 100 billion nerve cells. Only one other mammal on earth has more, a dolphin called the long-finned pilot whale.

Whether you are a dolphin, a human, or a cat, the nervous system helps you move around and sense the world. Keep asking great questions, Max. Who knows, you might just grow up to be a scientist.

One last thing. Gizerian and her students recently helped a few fifth graders visiting WSU learn about the brain and they built their own neuron. You can use play dough or make your own dough and shape it into your own neuron model and label its different parts. Send us a photo of your project sometime at

Dr. Universe