Discovery

Although many animal species cry vocally, the production of tears in response to emotion, both happy or sad, is a trait unique to humans. So why do we cry? What could the evolutionary advantage be to producing tears in response to joy or despair? The science on this topic has been surprisingly sparse until very recently, but now new research seems to be shedding some light on some common preconceptions about the effect and consequences of our tears. Does having a good cry make you feel better, for example, or do women really cry more than men? Researchers in Israel have even discovered that our tears may contain hidden messages triggering surprising responses in those who come into contact with them. Geoff Watts gets the tissues ready as he investigates everything you ever wanted to know about weeping.

Kevin Fong concludes his grand tour of the planet Mars, in search of water. Some of the most spectacular Martian landscapes were carved by vast and violent quantities of water in the planet’s past. The Tolkienesque terrain of Iani Chaos is one such place as is the great canyon Ares Valles. Kevin also talks to scientists on the current Curiosity Mars rover mission about water in the deep history of Gale Crater and its central mountain Mount Sharp. The journey concludes with gullies on cliffs and craters, suggesting that water still gushes on the surface of Mars today. Could this mean that life exists on the Red Planet today?(Image: Mars Express spacecraft in orbit around Mars Copyright: ESA- Illustration by Medialab)

The planet Mars boasts the most dramatic landscapes in our solar system. Kevin Fong embarks on a grand tour around the planet with scientists, artists and writers who know its special places intimately- through their probes, roving robots and imaginations. This first part of the journey includes Mars’ gargantuan volcanoes, an extreme version of Earth’s Grand Canyon and the cratered Southern Highlands where future explorers might find safety from the Red Planet’s deadly radiation environment.Producer: Andrew Luck-Baker

Robots probably won't take over the world, but they probably will be given ever greater responsibility. Already, robots care for the elderly in Japan, and drones have dropped bombs on Afghanistan. Professor Noel Sharkey fell in love with artificial intelligence in the 1980s, celebrated when he programmed his first robot to move in a straight line down the corridor and , for many years, judged robot wars on TV. Now, he thinks AI is a dangerous dream. Jim al-Khalili hears how Noel left school at 15 to become an electrician's apprentice and amateur rock musician before graduating as a Doctor of Psychology and world authority on robots, studying both their strengths and their limitations.

Annette Karmiloff-Smith, from the Birkbeck Centre for Brain & Cognitive Development in London talks to Jim Al-Khalili about her Life Scientific. Starting out as a simultaneous interpreter for the United Nations she soon decided that not being allowed to express any thoughts of her own wasn't for her. After a chance encounter with Jean Piaget, one of the most renowned psychologists of all time, she decided to pursue psychology and over 40 years later she is a world expert in brain development and how babies and children learn. Her research has been cited not just by fellow psychologists, but by philosophers, linguists, educationalists, geneticists and neuroscientists. Her controversial response to guidance issued by the American Academy of Paediatrics, that parents should discourage TV viewing in children under two, is that if the subject matter is chosen well, and is scientifically based, a TV screen can be better for a baby than a book.(Image: Child watching television. Credit: Peter Macdiarmid/Getty Ima

Like football, science is an international endeavour complete with its own stars and prima donnas. Alok Jha investigates what it takes to make a winning team.

What if we could feel more alive and more alert by just eating smaller meals? Extreme calorie restriction may hold the secret to the a longer live. According to some scientists, living to 120 and beyond could be possible - but is it worth a life of hunger and food deprivation?(Image: Woman pinching 'spare tyre' on her waist. Credit: Science Photo Library)

What if we could stay young forever? Peter Bowes continues his quest to find out what science and lifestyle can do to help keep mind and body young. Is it possible to slow down or even reverse the aging process, through exercise? The latest trend in gyms is towards high intensity workouts. Some scientists say they're better for the body than less strenuous exercise like jogging - and just a couple of minutes a day could be all we need. And what if we could inject ourselves with hormones, to stay young?(Image: Woman running on treadmill in gym. Credit: Science Photo Library)

What if we could stay young forever? It may be a fantasy, but age management is big business and some people will stop at nothing to roll back the years. Pills, scans, injections, extreme diets and brain training - there's a vast array of apparent solutions on the market - but do they work and are they safe? Is age "reversal" possible? Peter Bowes investigates.(Photo: A woman is covered with sheets of 24-carat gold, said to be effective for anti-aging care. Credit: Getty Images)

As part of the BBC World Service’s “What if…?” season, biologist Dr Andrew Holding meets some of the people straddling the line between man and machine.Over 50 years ago the term cyborg was first used to describe a person whose capabilities are augmented by mechanical or cybernetic parts.Today, mechanical or electronic prosthetic limbs and organs are rapidly changing more and more of our lives. But how far can it, and will it, go? Andrew meets some of those who might describe themselves today as a cyborg. Our bodies are not permanent, and if we lost a limb or an organ, and if we could afford it, we might well think about replacing it with a new device. But what about replacing a perfectly healthy part of your body with a device to give you superhuman powers? What if we could all become cyborgs?

When a couple are expecting a baby, the big question is: girl or boy? Adam Rutherford explores the many ways Nature decides that question. If you’re a human, a kangaroo or a komodo dragon, it’s in the sex chromosomes. If you’re a crocodile, it’s the temperature of your egg. And if you’re a fish, it can be one sex first and, later in the life, the other. Adam’s investigation includes conversation with Professor Jennifer Graves, a leading authority on sex determination, at La Trobe University in Australia. She explains what the weird nature of the platypus’ sex chromosomes tells us about how human gender is decided.Adam also meets one of London Zoo’s Komodo Dragons, the world’s largest and fiercest lizard. Female dragons can produce young without mating with males, but all their babies are males. How so?

Sex is one of Nature’s great forces of change. Yet it is one of life’s great mysteries. Adam Rutherford investigates how and why living things first invented sex about 1.5 billion years ago. He begins by exploring why so many animals and plants have carried on doing it, given that sex has some big disadvantages compared to asexual reproduction.

The oldest known sexual beings, a 400 million year old fish sex movie and the prehistoric turtles which were fossilised in the act of copulation. Discovery this week is strictly adults-only as we begin a three-part natural history of sex. Adam Rutherford talks to the scientists studying the world’s most revealing fossils. (Image: Two carettocheylid turtles, fossilised in mating position. Credit: The Royal Belgian Institute of Natural Sciences)

From smell to navigation, it seems that some of the hardest problems in biology could be solved with the insights from theoretical physics.The physicist Erwin Schrödinger wrote a book in the 1940s called “What is Life?” in which he speculated on the role of quantum mechanics on the life sciences. Almost 70 years later, both quantum mechanics and biology have moved on a long way. But are the two fields converging?Avian navigation, light harvesting in photosynthesis and even olfaction – the science of smell, all provide hints that nature may have been making use of some of quantum mechanics’ weirder tricks for quite some time.Jason Palmer looks at the emerging field of quantum biology.(Music: ©Will Lenton @Mu_Mech)

A decade ago, the Human Genome Project revealed that only 1% of our DNA codes for the proteins that make our bodies. The rest of the genome, it was said, was junk, in other words with no function. But in September another massive international project, called ENCODE, announced that the junk DNA is useful after all. Adam Rutherford reports on the significance of this major discovery. He visits the Wellcome Trust Sanger Institute outside Cambridge where the vast amount of data about our genome is produced and analysed. And he finds out how this new information is beginning to give insights into the origin and treatment of diseases, such as cancer. Adam also discovers that the study of genomes has changed dramatically since he finished his PhD: it's now all done in machines and not at the lab bench.

Sir John Gurdon talks to Jim al-Khalili about how coming bottom of the class in science was no barrier to winning this year's Nobel Prize for Physiology or Medicine. We're familiar with Dolly the Sheep but many people find the idea of cloning humans rather disturbing. It seems to cut to the core of who we are; but, scientifically speaking, we are getting closer to a time when cloning people might be possible. John Gurdon gives it fifty years. After a famously bad school report for science, he won the Nobel Prize for cloning a frog, decades before Dolly the Sheep. Here he talks to Jim about his pioneering work on cloning and where it all might lead.

Science polymath and celebrated author, Jared Diamond has tackled some of the big questions about humanity: what is it that makes us uniquely human not just a third species of chimpanzee; and why do some societies thrive and others struggle to survive, or collapse?Jim Al-Khalili talks to Jared Diamond about how his passion for the birds of Papua New Guinea overtook his medical interest in the gall bladder, and led him to undertake a scientific study of global history. Once a Professor of Physiology, he became increasingly fascinated by the birds of Papua New Guinea.Now Professor of Geography at University of California in LA, he stresses the vital importance of the environment in determining the success or otherwise of a society. He argues first that it was settled agriculture that enabled the white man to develop guns, germs and steel and later that abuse of the environment is often responsible for their collapse. But can the history of humanity really be understood in much the same way as we might seek to

Andrea Sella is a science showman, whose theatrical demonstrations of chemistry are filling theatres up and down the country. He talks to Jim al-Khalili about his life scientific. Andrea is also Professor of Materials and Inorganic Chemistry at University College London and he and Jim discuss whether he would rather be known for his research into rare metals than for his whizz bang displays.

Baby girls born today in the UK can expect to live to 82 years old, whereas boys on average will die 4 years earlier.Evolutionary biologist Dr Yan Wong looks at the latest evidence suggesting that where ageing is concerned, men seem to be at a genetic disadvantage. From research on ancient Korean eunuchs to laboratory fruit flies, new studies seek the answer to why males across the animal kingdom live faster and die younger.So, is the gender gap here to stay?

The most notorious fraud in the history of Science is the focus of this week’s Discovery. Exactly one hundred years ago, British scientists announced their discovery of fossilised skull and jaw bones of what appeared to be the earliest human – a species of humanity closer to our prehistoric ape ancestors than any found before it. In 1912 it was a sensational find. In 1953 it was revealed as a horrible hoax. Jonathan Amos talks to palaeontologists and archaeologists about the case of Piltdown Man and asks, could anything as scientifically scandalous happen today? He visits Chris Stringer, professor of human origins at London’s Natural History Museum. The museum is putting the original fraudulent specimens on display after almost sixty years of being hidden in disgrace. Archaeologists Miles Russell and Matthew Pope discuss the prime suspect in the case and ruminate on his motivations.Could the world of human origins research be fooled by a hoaxer today?Producer: Andrew Luck Baker