Sideways Radio 4, 4pm

Author Matthew Syed

(right) looks at more ideas that shape people’s lives, beginning with the concept of social contagion. He explores how it’s been used to explain a fainting outbreak at a school, but also asks whether our desire to find a reason can sometimes lead us to be too dismissive of these incidents.

In The Skewer: 100 Years Of The BBC (Radio 4, 11pm), Jon Holmes plunders the corporation’s archive – and then reshapes what he finds.

The Compass: Stories From The New Silk Road (BBC World Service, 9.30am & 8pm) looks at the impact of China’s ambitious plans for other countries, starting with Ecuador.