Red never stops smiling. She's eight years old and suffers from "selective mutism" (My Child Won't Speak, BBC One, Tuesday 2 February, 10.35pm). No one knows what causes it. Red - so called because of her hair - talks only to her parents. She uses a whiteboard to communicate with her grandad, John. It makes for a fairly limited exchange. "You can't have a relationship with a child who won't talk to you," he sighs. They are filmed in a pedalo. Grandad keeps up a stream of chat but eventually runs out of breath. A pedalo is hard work. And all he gets from Red is a smile.
"Just tell her you understand how she feels and that she is not doing it deliberately," says Maggie Johnson, a speech therapist. John tries. But he needs help too. He is bewildered by Red's silence. He rubs his cheek, adjusts his glasses and blows his nose. He tries to explain how he feels but can't. "It's hard to put into words," he says.
Megan, another selective mute, lives in Dover. She and her dad are flying a kite on the cliff tops. Not one scream of delight. The kite flaps and flutters in the blue. At school everyone seems to wear red except Mrs Johnson, who looks after Megan. Her yellow jumper matches her green glasses. She ask questions to which she gets no answers.
But Miriam, Megan's speech therapist, has an idea. She and Megan sit in the front room with mum. The three of them are going to count to ten taking the numbers in turn. Mum starts. "One." "Two," says Miriam. And then the faintest whisper - "three" - from Megan. Mrs Johnson is outside sitting on the stairs like a naughty child. "Was that ...? Did she ...?" She claps her hand to her mouth.
The next time they play a different game and Mrs Johnson is allowed to take part. "What is the colour of the sun?" she asks. Megan sits, mouth padlocked. A car passes outside. Then another. Mrs Johnson is probably counting them. "Yellow," murmurs Megan suddenly.
Her recovery has begun. She says "here" when her name is called during registration and she tells the teacher her favourite sweets are "cola bottles". "Have you spoken to Megan?" the director asks a boy with a black eye. What could he have said to provoke such a pugilistic response from the formerly mild-mannered Megan?
Perhaps Megan had been taking lessons from 15-year-old Danielle who was pummelling a punch ball. She used to suffer from the phobia but overcame it by changing schools and starting again with people who did not know her. But she still can't go into a shop and buy a bar of chocolate. "I just want to want to be normal," she says. "I just want to be like everyone else." Everyone else, of course, wants to be different.
Red has got a mobile phone. She takes grandad to the bottom of the garden and then runs back to the house. He waits. His phone rings. Red's mum has told him not to answer it. He waits. It rings again. This time to notify him that he has a new message. It's Red. "It's great to have you here." That's the first time he has heard her voice. Later they fly a kite under a swirling, Turneresque sky. John's smile is bigger than Red's.
Con Slobodchikoff has spent the past 30 years studying prairie dogs (Natural World: Prairie Dogs - Talk of the Town, BBC Two, Wednesday 3 February, 8pm). He believes their language is second only to that of humans in its complexity. He wants to show that prairie dogs have "words" for different predators. But since coyotes and badgers seem to be in short supply, Con and his team, Bill and Patricia, have to improvise.
They get a plastic coyote and nail it to a board. Bill drags it along the ground. The prairie dogs nudge one another. "Oi Frank, have you seen this?" says one. "Go and wake Pepe. He won't believe it." As Roger scampers into the burrow to get the sleeping Pepe, Sheila, another prairie dog, calls her friend Sally over to stare at Bill and Patricia stuffing a badger skin they got off eBay.
Sheila and Sally eat some grass and discuss Bill's butt. Eventually the badger fills out a bit and is drawn past the burrows. There is lot of jeering. One creature skips from side to side shouting "come and have a go if you think you're hard enough", much to the amusement of his mates.
Con takes off to study his recordings. Apparently the prairie dogs do make different sounds for different predators. Back at the burrows, they're taking bets that tomorrow, Bill and Patricia will run a fox down their street. But it's hard to hear the odds above the noise. They just can't shut up, those dogs.