Of the Humble Neuron, Small of Wit Yet Mighty in Multitude

Welcome back

Last time, we met the big idea: a neural network learns from examples instead of following rules. We also peeked at its inner workshop, the part that turns “what I see” into “what I’ll do.” Today we open that workshop’s door. Inside, we find something surprisingly modest.

A mound with no architect

Picture a termite mound on the African savanna. Some stand taller than a person. Inside are tunnels, chambers and chimneys that keep the air cool and fresh, even under a blazing sun.

Now here’s the remarkable part: no termite knows the plan. There is no architect, no blueprint, no foreman. Each termite is tiny, nearly blind, and follows a few very simple habits. Roughly: “Notice what my neighbours are doing. If the signal around me is strong enough, add my little ball of mud here.”

That’s it. One termite, on its own, could never build a cathedral. But millions of them, each following that small habit and each reacting to the ones nearby, build something far cleverer than any single one of them.

Meet the artificial neuron

The inside of a neural network works in just the same way. It is made of many tiny units called neurons, and each one is about as simple as a termite.

A single neuron does only three things:

1. It listens. It receives a few signals from the neurons before it. Each signal is just a number.
2. It combines. It adds those signals together into one total.
3. It passes something on. Based on that total, it sends its own signal forward to the next neurons in line.

That’s the whole job. A neuron doesn’t “understand” chess, or faces, or language. It just listens, combines, and passes along, like a termite sensing its neighbours and deciding whether to add its bit of mud.

Where the cleverness lives

If each neuron is so simple, where does the intelligence come from?

From the many, and from the connections between them.

Just as the mound’s design lives in no single termite, a network’s knowledge lives in no single neuron. It lives in the pattern of how thousands, or even billions, of neurons pass signals to one another.

Your own brain works on a similar principle, with roughly 86 billion neurons. Artificial ones are much cruder than real ones, but the spirit is the same: simple parts, richly connected, producing something none of them could manage alone.

What to carry with you