Discovery

For eons, salt has been crucial to human health, culture, and diet. On this episode of The Evidence, we explore the strange science of salt taste – why it can be sweet, salty, or even a flavour enhancer. We look at how salt keeps our bodies running, and what happens if we have to little of it. And while too little salt may be bad, too much is also a problem. What does the science say about how much salt is optimal, and what can we do to make sure we’re eating the right amount? Claudia Hammond is joined by a panel of salty experts who will help find the answers to these questions and more.

Do YOU know what you're eating? Are you sure? Dr Chris van Tulleken is keen to make good food choices, and buy the best chicken possible for his dinner. High welfare, tasty, and good for the environment, ideally. But it's not as easy as that. How CAN he make good food choices if he has no idea what he's buying? Chris explores what we actually know about the food we buy, and to what extent we can trust what's on a label. He also uncovers the startling truth about two very different ways that we buy chicken - lifting the lid on why sometimes, even the most moral meat shoppers turn a blind eye...

We’ve heard about the potential problems around chicken welfare. But how does that square with their impact on the environment? Dr Chris van Tulleken finds out what it takes to produce the most eco-friendly chicken meat possible. And makes a devastating discovery. Welfare concerns, and environmental credentials, often pull in OPPOSITE directions. Does he want to eat the happiest birds, or the ones kindest to the planet? Halfway through his poultry quest, Chris remains massively conflicted: he loves chicken, but some of what he’s discovered makes him question how much he eats it. Will he still be able to look at it the same way as he goes deeper down the rabbit hole? And more importantly, should he keep serving it up to the family?

We eat chicken. A LOT of it. We might love the taste, but what about how we're treating those birds? After witnessing first-hand the reality of indoor chicken farming - how most of the chicken we eat is raised - Dr Chris van Tulleken wants to know: are the birds happy enough, or is our method of rearing cheap chicken actually cruel? If so, what’s the ‘happier’ alternative – and do carnivores like Chris care enough to pay the price for that, or does a love of meat ultimately trump ethics? Chris battles with his conscience, and finds the answer hard to stomach.

So we started farming this bird called chicken, and it spread around the world. But what does it actually TAKE to feed us the amount of chicken we want to consume? 100 years ago this was a scrawny, egg-laying bird, only good for a stew once her eggs ran out – no one ate chicken meat. Fast forward to today and it’s the most consumed protein on the planet. How did we come to eat it in the first place, and what are the consequences of producing chicken meat on the vast, industrial scales we now consume it? Dr Chris van Tulleken uncovers the extraordinary accident of history that birthed a new industry, and changed the way we eat – and think about – meat forever.

Dr Chris van Tulleken is on a mission to find out what we’re eating, why, and who or what might be influencing our decisions. And he’s starting his quest to uncover food truths with the most eaten meat in the world, and one of the most numerous animals on our planet: chicken. He’s recently been forced to confront a serious gap in his food knowledge - what happens before it gets to our plates - and has decided this, the world’s most popular meat, is an ideal starting point. Chris’ initial investigations reveal the vast scale of modern chicken consumption; and how a once revered jungle fowl was manipulated to become a modern food success story, a fast-growing heavy-breasted beast to feed the masses. Now, he's torn: is this a triumph of human ingenuity – or the creation of a monster?

Dr Julia Ravey and Dr Ella Hubber both have a love of science, but it turns out there’s a lot they don’t know about some of the leading women at the front of the inventing game. In Unstoppable, Dr Julia and Dr Ella tell each other the hidden, world-shaping stories of the engineers, innovators and inventors they wish they’d known about when they were starting out as scientists. This week, the inventor whose incredible capacity to solve problems inspired today’s most popular period products. Mary Beatrice Davidson Kenner – known as Beatrice – grew up in a family of inventors, creating her first invention at just six years old. And she didn’t stop there – she continued to invent throughout her adult life, including a new and improved sanitary pad in a time when there was still a big taboo around periods. However, as an African American woman during a time of racial segregation, Beatrice faced injustice and discrimination when trying to get her inventions patented. But if anything, this spurred Beatrice on, and at one point in time she held the most patents of any African American woman. Dr Julia and Dr Ella are joined by Professor Sharra Vostral and Ashleigh Coren as they tell Beatrice’s remarkable story. Presenters: Dr Ella Hubber and Dr Julia Ravey Producers: Ella Hubber and Julia Ravey Assistant producer: Sophie Ormiston Production co-ordinator: Elisabeth Tuohy Editor: Holly Squire

In her last year of high school, Olga González-Sanabria went on a field trip to the University of Puerto Rico’s school of engineering – and immediately knew that was what she wanted to do. She followed her passion and after university was recruited by Nasa, where she carried out instrumental work, without which we would not have the International Space Station. As the very first Latina woman working in engineering at Nasa, Olga’s career has not always been an easy ride, but is filled with remarkable achievements. Dr Ella and Dr Julia tell her story, and Olga herself gives us a first-hand account of her life so far. Presenters: Dr Ella Hubber and Dr Julia Ravey Producers: Ella Hubber and Julia Ravey Assistant producer: Sophie Ormiston Production co-ordinator: Elisabeth Tuohy Editor: Holly Squire (Photo: Olga González-Sanabria. Credit: Nasa Glenn Research Center)

Dr Julia Ravey and Dr Ella Hubber both have a love of science, but it turns out there’s a lot they don’t know about some of the leading women at the front of the inventing game. In Unstoppable, Dr Julia and Dr Ella tell each other the hidden, world-shaping stories of the engineers, innovators and inventors they wish they’d known about when they were starting out as scientists. This week, the story of an Indian chemist whose work laid the foundations to save thousands of lives. In a lab in 1950s Kolkata, Asima Chatterjee laboriously extracts chemicals from the Indian snakeroot plant. She knows she’ll have to send the products away – she doesn’t have the money or resources to analyse them in India. But the tireless and uncompromising chemist perseveres, and her work paved the way for modern-day chemotherapy treatments. Asima grew up in a time when it was uncommon for women in India to have an education, but went on to become a hugely influential figure in her field whose work is still repurposed and cited today. Dr Ella and Dr Julia take us through her inspirational journey, joined by Professor Sivapriya Kirubakaran and Dr Sarah O’Connor. Presenters: Dr Ella Hubber and Dr Julia Ravey Producers: Ella Hubber and Julia Ravey Assistant producer: Sophie Ormiston Production Coordinator: Elisabeth Tuohy Editor: Holly Squire

Dr Julia Ravey and Dr Ella Hubber both have a love of science, but it turns out there’s a lot they don’t know about some of the leading women at the front of the inventing game. In Unstoppable, Dr Julia and Dr Ella tell each other the hidden, world-shaping stories of the engineers, innovators and inventors they wish they’d known about when they were starting out as scientists. This week, the story of the woman who mastered viewing the world in microscopic detail – ultimately helping us discover the structure of DNA. Florence Bell’s scientific career began in the 1930s whilst studying at Cambridge University. The University didn’t grant degrees to women at the time, but this didn’t dissuade Florence. She was so talented at an imaging technique called X-ray crystallography that she started a PhD in the field – and it was during this time that she would make a pivotal discovery about the molecule of life. Florence is an unsung hero of the DNA story. Her work laid the foundation for a vital field of research, yet her contribution was buried for years. Dr Julia and Dr Ella tell Florence’s tale, with input from Dr Kersten Hall, science historian and visiting fellow at the University of Leeds. Presenters: Dr Ella Hubber and Dr Julia Ravey Producers: Ella Hubber and Julia Ravey Assistant producer: Sophie Ormiston Production Coordinator: Elisabeth Tuohy Editor: Holly Squire (Photo: Florence Bell. Credit: Courtesy of her son Chris Sawyer. No reuse)

Dr Julia Ravey and Dr Ella Hubber both have a love of science, but it turns out there’s a lot they don’t know about some of the leading women at the front of the inventing game. In Unstoppable, Dr Julia and Dr Ella tell each other the hidden, world-shaping stories of the engineers, innovators and inventors they wish they’d known about when they were starting out as scientists. This week, the story of an engineer who turned plastic into gold, all starting from her mother’s backyard. Every day, around 500 tonnes of plastic waste is generated in the Kenyan city of Nairobi. Hardly any of it is recycled – but engineer Nzambi Matee is on a mission to change that. Frustrated by the level of pollution, in 2017 Nzambi constructed a laboratory in her mother’s backyard. It was here that she used her self-taught engineering skills to convert plastic waste into bricks that are stronger and more eco-friendly than concrete. Since then, Nzambi’s backyard operation has grown into a company – Gjenge Makers – and the bricks are widely used across Nairobi. And at only 31, Nzambi is just getting started. As Dr Julia and Dr Ella trace Nzambi’s journey, we hear from Nzambi herself about what it took to get to this point, as well as her ambitions for the future. Presenters: Dr Ella Hubber and Dr Julia Ravey Producers: Ella Hubber and Julia Ravey Assistant producer: Sophie Ormiston Production Coordinator: Elisabeth Tuohy Editor: Holly Squire (Photo: Nzambi Matee, Kenyan entrepreneur and inventor, holds plastic polymer recycled to make bricks. Credit: SIMON MAINA/AFP via Getty Images)

Dr Julia Ravey and Dr Ella Hubber both have a love of science, but it turns out there’s a lot they don’t know about some of the leading women at the front of the inventing game. In Unstoppable, Dr Julia and Dr Ella tell each other the hidden, world-shaping stories of the engineers, innovators and inventors they wish they’d known about when they were starting out as scientists. This week, the story of the Hollywood starlet whose brilliant ideas would go on to revolutionise the way we live. Known as the ‘most beautiful woman in film’ during the 1940s, Hedy Lamarr was one of the most in demand Hollywood actresses of her time. But she wasn’t just a movie star. From a young age, she also had a knack for inventing – she liked to take her toys apart just to see how they worked. And she carried this passion into her adult life – creating an invention that laid the groundwork for technology many of us couldn’t live without: Wi-Fi, Bluetooth, and GPS. But it didn’t come without struggle. Dr Julia and Dr Ella take us through Hedy’s remarkable journey, and we get a first-hand look into Hedy’s life from her daughter Denise Loder-DeLuca. Presenters: Dr Ella Hubber and Dr Julia Ravey Producers: Ella Hubber and Julia Ravey Assistant producer: Sophie Ormiston Production Coordinator: Elisabeth Tuohy Editor: Holly Squire (Photo: Hedy Lamarr, Austrian-born American actress and inventor. Credit: Eric Carpenter/John Kobal Foundation/Hulton Archive/Getty Images)

The process of childbirth can be painful yet amazing, but at times and in some places, also very dangerous. Recorded in Malawi, East Africa, Claudia Hammond is joined by a panel of maternal health experts to figure out why it is that the equivalent of a large jumbo jet full of women die every day due to pregnancy or childbirth. Together, they examine how so many women can still be at risk during this period despite a greater access to healthcare. They also look into whether an eighty-year-old drug could be a game-changer when it comes to haemorrhage. Plus, they consider a study of 1.3 million women which asked what it is that women actually want from maternal healthcare. With Owen Chikwaza from the Malawi Ministry of Health, Linda Mipando of Kamuzu University and Elimase Kamanga-Gama, Director of the White Ribbon Alliance Malawi, Claudia looks at the many challenges and successes within the field, drawing from local experiences to offer global insights. Produced by: Margaret Sessa-Hawkins Editor: Holly Squire Production Coordinator: Siobhan Maguire Presenter: Claudia Hammond Studio Engineers: Andrew Saunderson and David Sproule (Photo: Pregnant woman being examined by a doctor. Credit: Holly Squire BBC)

Underwater cameraman Roger Munns set himself and his team an incredible challenge. In 2008, they visited Tonga to film the biggest courtship ritual of the animal kingdom, the humpback heat run, for the very first time underwater and up close. In the first few days, Roger had intimate encounters with the whales but most of the time, he was sat on the back of the boat, waiting to find a heat run. After two unsuccessful weeks, he started to wonder whether they would ever see one. But a few days later somebody spotted a heat run, and everything sprang into action. Roger got in position and dove down ten meters underwater on a single breath. From then on, his job was just to wait and hold his camera ready. In a moment that seemed to stretch out time, he waited, nervously, for a group of 40-ton bus-sized whales to speed past him… And Victor Vescovo describes his adventures into the deep, diving to the deepest parts of all five oceans. Victor's longest dive was solo to the lowest point on Earth - the Challenger Deep at the bottom of the Marianas trench in the western Pacific. On reaching the bottom, some 35,853 feet below the ocean surface, should something have gone wrong, there was no hope of rescue. Victor describes his feelings before making this historic descent and on the way down. Touching down on the sea bed, he was astounded by the abundance of marine life. Victor describes how he hopes that the mapping, observations and sample collections he has made on his dives will advance scientific understanding of the deep oceans, and where his eternal quest to explore might take him next. Produced by Florian Bohr and Diane Hope Credits: Humpback whale mother and calf sounds - Acoustic Communications CNRS team & CETAMADA Humpback whale calf sounds - Lars Bejder (MMRP Hawaii), Peter T. Madsen (Aarhus University) & Simone Videsen (Aarhus University)

Primatologist Catherine Hobaiter has spent more of her adult life in the rain forests of Uganda, with family bands of chimpanzees, than she has with her own human family members. For more than 20 years now she has spent 6 months every year at a remote field station, getting up before dawn every day to observe and collect behavioural data on family bands of chimps as they wake up and go about their daily lives. What is she trying to find out, that has gripped her for so long? It turns out that life in a chimpanzee troupe is every bit as gripping as a soap opera. But there are many more moments of beauty, revelation and the joy of discovery, as Catherine pursues her continuing, multi-decadal quest to understand what it means to be a chimpanzee. And when Sara Dykman set out to bicycle with the monarch butterfly migration, from the mountains of central Mexico, across the USA to Canada, she didn't think about the 10,201 miles that she would cover. Coping with headwinds, heavy rain storms, and everything from dirt roads to busy highways were not the challenge for Sara though. It was seeing how little of the Monarch's only food plant, milkweed, was left for them to feed on during their amazing, multigenerational, multinational migration. However, Sara found solace in the many conservationists and backyard butterfly gardeners she met along the way, and in the 9000 schoolchildren she gave talks to en route. The most emotional part of the journey for Sara was the last three miles - arriving successfully back at the monarch's overwintering site in Mexico. Produced by Diane Hope. Credits: Monarch butterfly recordings - Robert Mackay

Professor Ben Garrod and Dr Jess French get under the skin (and blubber) of the California sea lion, to crack the key to its success both on land and at sea. Its ability to dive hundreds of meters down, keep warm in icy waters, and run on land, can all be explained through its unique internal anatomy. They are joined by zookeeper and sea lion trainer Mae Betts, who adds insight into the intelligence of these sleek marine mammals. Co-Presenters: Ben Garrod and Jess French Producer: Ella Hubber Editor: Martin Smith Production co-ordinator: Jana Bennett-Holesworth

The tiny sap-sucking aphid, at just a few millimetres long, is the scourge of many gardeners and crop-growers worldwide, spreading astonishingly rapidly and inflicting huge damage as it seeks to outwit many host plants’ natural defences. With insights and guidance from aphid expert George Seddon-Roberts at the John Innes Centre, Norwich, some delicate dissecting tools, and a state of the art microscope, Prof Ben Garrod and Dr Jess French delve inside this herbivorous insect to unravel the anatomy and physiology that has secured its extraordinary reproductive success, whilst offering new clues as to how we could curtail its damaging impact in the future. Co-Presenters: Ben Garrod and Jess French Executive producer: Adrian Washbourne Producer: Ella Hubber Editor: Martin Smith Production co-ordinator: Jana Bennett-Holesworth

Ominously called the lamb vulture, there are many myths and misconceptions surrounding the bearded vulture. Flying the mountainous ranges across central Asia and eastern Africa, with a wingspan of almost three meters, the bearded vulture is am impressive Old World vulture. Prof Ben Garrod and Dr Jess French are looking past the beautifully coloured plumage, and delving deep inside to learn what this bird of prey really eats and what keeps its great wings aloft.

Wild Inside returns for a new series to take a look at some of our planet’s most exceptional and unusual creatures from an entirely new perspective: the inside. Whilst we can learn a lot from observing the outside, the secrets to the success of any animal – whether they swim, fly, or hop – lies in their complex internal anatomy. How do these wild animals survive and thrive in harsh and changing environments? To truly understand we need to delve inside. Professor Ben Garrod, evolutionary biologist from the University of East Anglia, and expert veterinary surgeon Dr Jess French, open up and investigate what makes each of these animals unique, in terms of their extraordinary anatomy, behaviour and their evolutionary history. Along the way, they reveal some unique adaptations which give each species a leg (or claw) up in surviving in the big, wild world. The series begins with an icon of the outback – known best for its hopping, boxing, and cosy pouch – the red kangaroo. Despite the immense heat and lack of water, these marsupials dominate Australia, with their evolutionary history driving them to success. From the powerful legs which allow them to hop up to 40km an hour, to an unexpected reproductive system that keeps their populations plentiful, Ben, Jess and marsupial expert Dr Jack Ashby reveal a mammalian anatomy which holds many surprises.

Hannah Fry explores two tales of data and discovery. A young researcher gains access to a secretive data set and discovers a system causing harm to the very people it is supposed to help. One day a student makes a discovery which, if true, could shake the intellectual foundations of a global movement, and undermine politicians around the world. Producer: Lauren Armstrong Carter