A great advantage of the internet and social media is that they allow us to keep in touch with all our friends, even when they move away. That means our group of friends can carry on expanding indefinitely. Except, says anthropologist Robin Dunbar, it can’t. There’s a limit to the number of friends we can have. It is known as Dunbar’s number. Presented by David Edmonds (Image: Group of friends, Credit: Shutterstock)

Friends

What are the big ideas shaping our world now?

The 2020 pandemic has transformed our world, but it won’t be the last to do so. How should we prepare for the future? Along with one of the world’s leading epidemiologists, David Edmonds explores the science of pandemics – and why it is so uncertain.

Fighting pandemics

Some people are addicted to drugs, others to alcohol. Addicts often crave a substance, and yet when they inject or consume it, it doesn’t bring them any pleasure. David Edmonds finds out how humans can want something, but not like it.

The science of addiction

Love him or loathe him, we can all agree that Donald Trump is not a ‘normal’ President. Previous presidents would never behave like President Trump. Is the abnormal becoming normal? And how can we tackle people who say uncomfortable things?

The new normal

Have you ever thought that your city is too regulated? Or that the city you live in doesn’t do enough to police people who break the rules? In this episode, David Edmonds has been speaking to Michele Gelfand, a psychologist whose research on rule makers and rule breakers could change the way we think about our cities. We’ll find out why you might be able to tell the time better in a city that's like Switzerland; why Japanese police officers reportedly egged people on to commit more crimes; and why living in a city like San Francisco could make you more creative. Presented by David Edmonds.
Produced by Robbie Wojciechowski for the BBC World Service.

Do cities need rules?

We spend around a third of our lives asleep, but the reason we sleep is still something of a mystery. Could it be the biggest mistake the evolutionary process has ever made? What does sleep actually do for us? David Edmonds meets Matthew Walker, one of the world’s leading sleep scientists, to discuss some of his findings. We’ll hear about how the clocks going back has an effect on heart attack rates, and consider why, if you’re struggling to sleep, the worst thing you could do would be to stay in bed.

Friends

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