Eternal flames

As the Olympic torch makes its way through France, we investigate the fires that continually smoulder and those which are stomped out.

You might expect snow to make a solid fire extinguisher, but in Canada, it is somehow keeping embers alight. These ‘Zombie fires’ keep burning through the winter, releasing huge amounts of carbon into the air and enhancing the tinderbox for summer wildfires.

While wildfires leave trails of destruction, for some plants and animals, they act as a catalyst for life – helping them to spread their seeds or flower. And the extent of these blazes can also be marshalled by nature – with elephants and beavers building natural fire breaks into landscapes to prevent uncontrollable flames.

We hear about when the first fires happened on Earth and how we can study ancient fires which have long since gone out. Plus, we unpick the key to monogamy (in mice), why cicadas love prime numbers as well as your thoughts on snakes...

Presented by Caroline Steel with Philistiah Mwatee and Chhavi Sachdev Produced by Alex Mansfield with Florian Bohr, Harrison Lewis, Julia Ravey and Noa Dowling Studio Management by Emily Preston