Do you stick your tongue out or scowl when you concentrate? Maybe, like one of our listeners, you screw up your face when you’re playing music. Do these facial expressions actually help with the task in hand? And could they hold clues to humans’ evolutionary past?

In this edition of CrowdScience we tackle the science of face-pulling, along with several more burning science questions sent in from listeners around the world. We explore why it’s almost impossible to talk without moving your hands; and why bilingual people often switch to the first language they learned when they’re counting, even if they speak another language the rest of the time.

Presented by Anand Jagatia and Marnie Chesterton

Produced by Cathy Edwards

(Photo: A boy sits at a table, looking down in concentration as he draws in a note pad. Credit: Getty Images)

Laser swords, time machines, matter transporters - before the turn of the millennium, movies, books and television promised some extraordinary future technology. Now we’re twenty years into the next century and CrowdScience listeners are wondering: Where is it all?

Marnie Chesterton delves into the sci-fi cupboard to dust off some imaginary gadgets and find out if any are finally becoming reality. How far into the future will we have to go to find a time machine as imagined by H.G. Wells in 1895? Where are the lightsabers wielded by fictional Jedi? Why are we still using cars, planes and trains when a matter transporter or a flying taxi could be so much more convenient? Marnie is joined by a panel of experts to find out if and when any of these much-longed for items are going to arrive.

Presenter Marnie Chesterton. Producer Jennifer Whyntie

(Photo: Dr Who, Tardis. Travelling through time and space. Credit: BBC Copyright)

Farming is a relatively recent invention for our species. For most of human history, people were hunter-gatherers. They moved around the landscape to get their food, hunting prey and gathering fruits and cereals from their environment.

But then, around 10 thousand years ago, human society shifted, and the first farmers appear in archaeological records around the world. So how did this idea start? Who planted the first seed and domesticated the wild ancestors of our cows and chickens?

That’s what Listener Brian wanted to know, and so CrowdScience presenter Anand Jagatia seeks out the archaeologists, geneticists and anthropologists who can give us the answers.

Presenter: Anand Jagatia,

Producer: Rory Galloway

(Photo: A farmer working in a green cotton field with two bulls. Credit: Getty Images)

For some people, the idea of eating soil is weird at best and at worst disgusting and dirty. But globally the practice of geophagy – or the regular and intentional consumption of earth – is more common than you might imagine. The ancient Greek physician Hippocrates described it 2500 years ago and even today, eating soil, earth and clay can be seen in a wide range of human cultures as well in hundreds of animal species. But what’s the point of it? And what’s going on in the body to drive cravings for things that aren’t bona fide food?

That’s the question bothering CrowdScience listener Amy. Anna Lacey discovers the special properties of the soil people eat and the purpose geophagy might serve for our health. She also finds out the extent to which our bodies can tell us what we’re lacking and drive us to crave the substances we need to reset the balance.

Produced and Presented by Anna Lacey

(Photo: Hands holding some soil. Credit: Getty Images)

It’s frustrating to be stuck in traffic. Listener Collins from Nairobi, Kenya, spends at least three hours a day in traffic and he counts himself lucky. Many of his friends will easily spend six hours in traffic jams to get back and forth from work. Collins wants to know whether there is hope for his hometown – has any city managed to eliminate the worst of the traffic hot spots and how did they do it?

Collins is not alone in his frustration. CrowdScience finds that congestion plays a major factor in the happiness and health of urban citizens. Commuters have been measured to have stress levels equivalent to that of riot police facing angry protesters.

So should our cities cater less for cars and what are the alternatives? Presenter Gareth Barlow heads to Copenhagen to meet the politicians and urban designers who have transformed the Danish capital from a city for cars to one for bikes and people.

Presenter: Gareth Barlow.

Produced by Louisa Field

(Photo: Afternoon traffic along Likoni road in Nairobi's Kilimani susburb. Credit: Getty Images)

Breathing is automatic: awake or asleep, running or resting, our bodies unconsciously make sure we get enough oxygen to function. But - unlike other bodily functions such as heart rate and digestion - it’s not hard to control our breathing consciously. If you’ve ever been to an exercise, meditation or yoga class, you’re probably familiar with instructions about how and when to breathe.

It was one of these instructions - “breathe in through your nose and out through your mouth” - that prompted CrowdScience listener Judi to wonder if this really was the best way to breathe during her exercise class. Is there good evidence to support the benefits of different breathing techniques - whether through the nose or mouth, fast or slow, noisy or quiet? And is consciously controlling your breath more about improving psychological focus, or optimising body mechanics?

Sports scientist Mitch Lomax takes us through the biology, chemistry and physics of breathing, and shows us how to train our respiratory muscles. We meet yoga guru Hansa Yogendra in India, where the study of pranayama - literally “breath control” in Sanskrit - is thousands of years old; and find out what scientists have discovered about the effects of these ancient techniques on the body and mind.

Presenter: Anand Jagatia.

Producer: Cathy Edwards

(Photo: A woman jogging outside, wearing sports clothes on a blue sky background. Credit: Getty Images)

For decades, people suffering from chronic depression have relied on medicines that affect the levels of chemicals in the brain like serotonin, which regulate mood and emotion. But ten percent of people don’t benefit from any of the existing treatments for this devastating condition.

Sisters Annie and Kathryn have both been diagnosed with long-term depression that makes it hard for them to experience pleasure as others do. But they’re interested in whether there are new solutions on the horizon that could improve their wellbeing, in particular ones that don’t necessarily involve conventional medication.

Datshiane Navanayagam learns how a technique called mindfulness could strengthen neural connections in bits of the brain that communicate with each other. This, it’s said, may harness the ability of the brain to adapt and self-repair which can change people’s emotional responses to life’s ups and downs. She meets a psychologist who shows how this simple technique could improve our overall ability to process information and reverse negative thought patterns.

CrowdScience also hears about cutting edge research into the use of psychedelics as potential treatment for depression and heads to the UK’s only centre for ketamine therapy, where patients say a drug once popular with partygoers, is having a profound effect on their mental health.

Produced by Marijke Peters for BBC World Service.

(Photo: A woman sitting on the top of a mountain and meditating. Credit: Getty Images)

Singing can lift our spirits, but research suggests it could also benefit our health, improving breathing for people with lung conditions and helping us cope with dementia. Could it even have a preventative effect?

CrowdScience heads to Cheltenham Science Festival in the UK county of Gloucestershire - one of the first places to pioneer this kind of “social prescribing” - to find out. Presenter Anand Jagatia teams up with panellists Dr Daisy Fancourt, Senior Research Associate in Behavioural Science, Dr Simon Opher, family doctor and Clinical Lead for Social Prescribing, and Maggie Grady, Director of Music Therapy at charity Mindsong to learn more. They’re joined on-stage by their Breathe In Sing Out and Meaningful Music volunteer singing groups to find out what this much-loved musical pastime can do for us.

Producer: Jen Whyntie

(Photo: Students singing in a choir with their teacher. Credit: Getty Images)

Medical intervention has disrupted natural selection in humans as many more children survive into adulthood than did a few centuries ago. And as our DNA continues to evolve, in order to adapt to our environment, how might human beings of the future be different from us? Anand Jagatia explores how some humans, over just a few thousand years, have adapted genetically to live at high altitudes of the Tibetan Himalayas or in the cold climates of Inuit Greenland.

Several Crowdscience listeners got in touch to ask about the ways in which humans might evolve in future but understanding how we’re adapting to modern ways of living is much harder to measure. So what adaptions do evolutionary biologists expect for the human race? How will IVF, gene-editing, mass migration and our constantly changing culture affect how we evolve?

Presenter: Anand Jagatia. Produced by Dom Byrne and Melanie Brown for BBC World Service

(Photo: People in a crowded street. Credit: Getty Images)

As scientists keep finding ever more fascinating facts about the invisible housemates that share our homes, we dust off our episode on what might be lurking in quiet household corners or under our beds.

Marnie Chesterton reminds us how dust can contain all sorts of secrets about our habits and everyday lives, and Anand Jagatia bravely ventures into parts of our homes that are usually overlooked. He heads out on a microbial safari with expert tour guide Dr Jamie Lorimer from the University of Oxford to find out what kind of creatures are living in our kitchens, bathrooms and gardens - from bacteria normally found in undersea vents popping up in a kettle, to microbes quietly producing tiny nuggets of gold. For so long this hidden world has been one that we’ve routinely exterminated - but should we be exploring it too?

Presenters: Marnie Chesterton and Anand Jagatia. Produced by Jen Whyntie for BBC World Service.

(Photo: A woman using a damp sponge to clean dust collected on a window sill. Credit: Getty Images)