What if no one
ever talked
to a baby?

The full narration of the video.

Most people think kids learn to talk because their parents teach them, one sentence at a time. So what if a baby were born and nobody ever spoke to him? What would he come out saying? Over two thousand six hundred years ago, an Egyptian king actually wanted to find out.

An ancient Greek history tells it: he handed two newborns to a shepherd. Feed them milk, he ordered, but never say a word to them. Two years later, the children ran up and cried: Bekos! The king looked it up — a far-off people's word for bread. So he declared theirs the oldest language on Earth.

But it's most likely just a legend. In real life, has a child ever grown up with no one talking to them? Sadly, yes. In nineteen seventy, in Los Angeles, people found a thirteen-year-old girl. She'd been shut in a small room since she was little. Almost no one had ever talked to her.

She picked up words fast — within months, she knew the names of hundreds of things. But years later, she could still only string two or three words together. What order words go in, how to ask a question — she never fully got it. Another girl was found at six and a half, and she'd barely heard speech either. Yet in just over a year, she went from her first word to full sentences.

What made the difference? Age. Scientists suspect the brain has a window when language comes easiest. After ten or so, it gets hard. But cases like these are so rare that the evidence is still thin. So does a baby start talking on his own? Halfway. Around six or seven months, babies start to babble. Even deaf babies raised by parents who sign babble with their little hands. But babbling is just practice. To turn it into words, someone has to answer: he babbles, you reply.

In one experiment: nine-month-old American babies heard a real person speak Chinese, and learned to tell Chinese sounds apart. Put the same person on a screen, and they learned nothing. One child shut away alone won't grow a language. But what about a whole group of kids, with nobody teaching them? In nineteen seventy-seven, Nicaragua opened its first school for deaf children. Before that, each kid had stayed home with a few gestures of their own.

Teachers tried lip-reading. It didn't work. But on the playground and the school bus, the kids signed to each other, and their signs grew in number, and in rules. Younger kids joined and made it faster and finer. In about ten years, a brand-new sign language had simply grown. So here's the answer: a baby no one talks to won't come up with much alone. But give him someone to go back and forth with — even if they are all just kids — and language grows by itself.

Talking isn't taught line by line. It grows out of conversation. So what did you think before — do kids learn to talk by being taught, or by listening?