Our planet is getting rather cosy. In just over 200 years, the global population has grown from 1 billion to almost 7.5 billion – and the best estimates suggest it’s going to keep on increasing. But just how far can it go? When will we reach ‘peak human’? That’s what CrowdScience listeners Alan Donaldson and Francoise Brindle want to know: what’s the latest estimate for how many people the Earth can support?

It’s a question that’s been bothering some of the world’s greatest thinkers for hundreds of years, and now presenter Marnie Chesterton goes on her own quest for answers. Her journey takes her through the technology and innovation that keeps our growing population alive, and she looks to Dhaka, Bangladesh, to find out what a more densely populated world might feel like. But are there signs that things are already levelling off? And could improving photosynthesis allow populations to grow without destroying the environment?

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Presenter: Marnie Chesterton

Producer: Anna Lacey

(Image: People on busy street. Credit: Getty Images)