Two cold callers feature in this episode. Jennifer Langston from Ontario in Canada sent this message to [email protected]:

"My husband has just taken up cold water swimming and he'll swim in temperatures as low as 6 degrees Celsius. I worry that it's too cold for him, but he claims that 'swimming in cold water is good for you', which drives me bonkers. Can you tell us if there is any scientific proof behind this?”

Adam takes a trip to his local lido and asks the locals why they get a kick out of a chilly winter dip. Meanwhile, Hannah calls the Antarctic to talk to meteorologist Richard Warren about the perils of a frozen beard.

Our second cold caller, Sarah Dudley, asks why women get cold feet in bed. Thermal physiologist Heather Massey is on hand with the answer.

But when it comes to the natural world, other animals are masters of sub-zero living. Frozen Planet producer Kathryn Jeffs, from the BBC's Natural History Unit, explains why polar bears are perfectly designed for the Arctic. And we discover why Paddington Bear is better suited to Peru.

Presenters: Hannah Fry, Adam Rutherford

First broadcast on BBC Radio 4 in 2020.

“I suppose a cold is called a cold because we catch it in the winter," writes Alison Evans from St Albans. "But why is it that we get more colds in winter than in the summer?”

This week's Cold Case is all about the common cold, a set of symptoms caused by hundreds of different strains of cold and flu viruses.

Adam uncovers the stinky history of infectious disease with medical historian Claire Jones.

Virologists Jonathan Ball and Wendy Barclay describe how spiky viruses lock on to our cells, but why many of the symptoms of a common cold are due to our own body's overreaction.

Plus, we delve into the science of sneezing with nose doctor Carl Philpott.

Presenters: Adam Rutherford, Hannah Fry

"My question is about something I became aware of at a young age," explains Samantha Richter from Cambridgeshire.

"I was sitting on the carpet at school, being read a story by the teacher. My hair felt as though it was standing on end as waves of a tingly sensation washed over my head. I subsequently found certain scenes in films had this effect, when actors were talking softly, or someone was having their hair brushed."

"Then, a few years ago, I discovered that there is a name for the tingles, it's called ASMR. My question is, what is ASMR, and why do we experience it?"

In this episode, we explore the world of Autonomous Sensory Meridian Response. It's a trend which has risen quickly on YouTube, with devoted subscribers following their favourite 'ASMRtists' whose videos receive millions of plays.

Hannah speaks to Dr Nick Davis, who published the very first research paper on the phenomenon in 2015. And Adam is put to the test by Dr Giulia Poerio, to see if he is susceptible to the sensation of ASMR. Are there any proven benefits for devoted fans, or is it just a YouTube fad?

We've concocted our very own Curious recordings so you can find out if your brain begins to tingle. You'll find them in our normal podstream, where you can enjoy Adam and Hannah crafting a very ASMRy cocktail for your listening pleasure.

Presenters: Hannah Fry, Adam Rutherford

First broadcast on BBC Radio 4 in 2020.

Adam Rutherford concocts an Old Fashioned. First listen to our episode on ASMR, then grab some headphones and let Adam mix you a cocktail.

Hannah Fry mixes a mojito. This ASMR recording accompanies the episode of The Curious Cases of Rutherford and Fry on the science of ASMR.

Two questions about love and heartbreak in this episode for our Valentine's special edition.

Jessica Glasco, aged 29, wrote in to ask about the power of love and how it affects our brain.

Hannah tracks down Dr Helen Fisher, who conducted some of the first MRI studies on love by putting besotted couples into the brain scanner.

Adam talks to broadcaster Claudia Hammond, author of Emotional Rollercoaster, to find out how psychologists have grappled with the messy business of love. And we hear why a small furry vole was thought to hold the answer to the mystery of monogamy.

Our second question concerns the pain of heartbreak - why does our heart ache? Can emotional hurt cause physical pain? On call is our very own agony aunt, Irene Tracey, Prof of Pain Research.

Presenters: Hannah Fry, Adam Rutherford

First broadcast on BBC Radio 4 in 2020.

"How do you make gold?" asks curious listener, Paul Ruddick.

Inspired by the promise of riches, Hannah and Adam embark on a mission to discover the origin of gold. It's a tale that takes them from the clandestine codes of Aristotle to the alchemy of Isaac Newton, alongside materials scientist Mark Miodownik.

They boldly go into the cosmos with astronomers Lucie Green and Andrew Pontzen, to learn what happens in the most exotic areas of space. By the end one thing is for sure - you'll never look at your gold jewellery in quite the same way again.

Presenters: Hannah Fry, Adam Rutherford

First broadcast on BBC Radio 4 in 2020.

Rutherford & Fry reveal which of your questions they’ve chosen for Series 15. Plus they select more of their favourite strange-but-true science papers, including how to use mathematics to challenge a parking fine and training tortoises to yawn.

"What would become the dominant species if, or when, humans go extinct?"

This cheery question leads Drs Rutherford and Fry to embark on an evolutionary thought experiment.

Zoologist Matthew Cobb questions whether humans really are the dominant species. Ecologist Kate Jones explains why some species are more extinction-prone than others. Plus Phil Plait, AKA The Bad Astronomer, busts some myths about why the dinosaurs went extinct.

Send your questions for future series, along with any Curio correspondence for the podcast, to: [email protected]

Presenters: Hannah Fry, Adam Rutherford

First broadcast on BBC Radio 4 in 2019.

"Why is it so difficult to predict the weather?" asks Isabella Webber, aged 21 from Vienna.

"I am sure there are many intelligent meteorologists and it seems rather straight forward to calculate wind speed, look at the clouds, and data from the past to make accurate predictions, but yet it’s not possible."

Adam delves into the history of forecasting with author Andrew Blum, beginning with the mystery of a lost hot air balloon full of Arctic explorers.

Hannah visits the BBC Weather Centre to talk to meteorologist and presenter Helen Willetts about how forecasting has changed, and whether people get annoyed at her if she gets the forecast wrong.

Plus mathematician Steven Strogatz suggests a chaotic explanation as to why we can't produce the perfect forecast.

Presenters: Hannah Fry, Adam Rutherford

First broadcast on BBC Radio 4 in 2019.