As CrowdScience celebrates its third birthday, the team takes time to revisit some of our early episodes, and catch up with listeners to discover if the answers we uncovered changed the course of their lives? We hear from Zach, who has learned to let go of a possibly lost memory and Erin, who discovered technology could hold the key to finding the man of her dreams. And two years after he emailed to ask why he couldn’t kick his habit, we ash Sharif whether he has finally managed to stop smoking?

(Photo: Man listening to podcast. Credit: Getty Images)

Buzzing insects that sting and fall into your food can be annoying. But perhaps we should think twice before taking aim with the fly swatter because bug populations around the world are in rapid decline. This worries CrowdScience listener Daria; she wants to know what will happen to our food production without the help from our tiny friends – the pollinators? And what can she do, as a city-dweller, to help the bugs?

The dollar value of agricultural services that insects supply – for free – is estimated to be 350 billion dollars worldwide. For scientists, a major challenge is the lack of long-term studies of insects on a global scale – in fact – entomologists worry that species are dying out faster than we can document their existence. The culprits, they believe, are climate change, invasive species, land-use and pesticides.

CrowdScience speaks to the scientists who want to save the bugs; one project capitalises on the chemical signals that attract certain species of pollinators while others are building ‘bee hotels’ to encourage native bees back into our cities.

Presenter: Marnie Chesterton

Produced by Louisa Field for BBC World Service.

(Photo: Hoverfly on Yellow Dandelion Flower. Credit: Getty Images)

66 million years ago, a huge asteroid hit the earth, wiping out most of the dinosaurs that roamed the land. It would still be tens of millions of years before the first humans appeared - but what if those dinosaurs hadn’t died out? Would we ever have evolved?

CrowdScience listener Sunil was struck by this thought as he passed a Jurassic fossil site: if dinosaurs were still around, would I be here now?

We dive back into the past to see how our distant mammal ancestors managed to live alongside huge, fierce dinosaurs; and why the disappearance of those dinosaurs was great news for mammals. They invaded the spaces left behind, biodiversity flourished, and that led – eventually – to humans evolving. It looks like our existence depends on that big dinosaur extinction.

But we explore a big ‘what if?’: if the asteroid hadn’t hit, could our primate ancestors still have found a niche – somewhere, somehow - to evolve into humans? Or would evolution have taken a radically different path: would dinosaurs have developed human levels of intelligence? Is highly intelligent life inevitable, if you give it long enough to develop? We look to modern day birds - descendants of certain small dinosaurs who survived the asteroid strike - to glean some clues.

With artist Memo Kosemen, palaeontologists Elsa Panciroli and Darren Naish, palaeobiologist Anjali Goswami, and Professor of Comparative Cognition Nicola Clayton

Presented by Marnie Chesterton and Anand Jagatia

Produced by Cathy Edwards for the BBC World Service

(Photo: Silhouette of people and Dino. Credit: Getty Images)

Science fiction is full of people settling on distant planets. But even the closest stars would take millennia to reach with current speeds of travel, by the time any passengers reached an extra solar planet, they would be long dead.

So CrowdScience listener Balaji asked us to find out whether humans could hibernate for interstellar travel?

To uncover the science fact behind this idea, Anand Jagatia holds a tiny hibernating dormouse at the Wildwood Trust in Kent, and meets Dr Samuel Tisherman who puts his patients into suspended animation for a couple of hours, to save their lives after traumatic injuries that cause cardiac arrest. We ask if Dr Tisherman’s research could be extended to put healthy individuals to sleep for much longer periods of time?

It’s a question that neuroscientist, Professor Kelly Drew is studying, in Alaska Fairbanks. She uses Ground Squirrels as a model to understand internal thermostats, and how hibernating mammals manage to reduce their core temperatures to -3 degrees Celsius.

Anand speculates wildly with science fiction authors Adrian Tchaikovsky and Temi Oh whose characters in their books ‘Children of Time’ and ‘Do You Dream of Terra Two?’ traverse enormous distances between habitable planets.

But is human stasis something that would actually be useful? John Bradford is the director of SpaceWorks, this company works with NASA to try to investigate human hibernation for space travel. He’s trying to make space-based human hibernation a reality, and it seems that may be closer than you’d think.

Presented by Anand Jagatia

Produced by Rory Galloway

(Photo: People in hibernation. Credit: Getty Images)

Australian listener Lizzy is trying to reduce her footprint on this planet and is particularly interested in palm oil. It is everywhere - in shampoo, lipstick and face cream and even food stuffs like biscuits and spreads. In fact, WWF say it is used in 50% of all supermarket products so it's something most of us will come into contact with every day.

Lizzy wants to know whether she should stop eating it. Because on the one hand, she sees emotive adverts depicting dying orangutans, deforestation and burning peatlands, releasing vast amounts of climate changing gases like carbon dioxide. On the other, she has read that palm oil is the most productive of the vegetable oils, using far less land than others. So would boycotting palm oil displace the problem elsewhere, she wonders? Would buying sustainable palm oil be best?

Partnering up with with another BBC World Service programme, The Food Chain, presenter Graihagh Jackson heads to one of the biggest producers of palm oil: Malaysia. She visits small holder plantations, who collectively provide 40% of the world’s palm oil, to find out how palm oil is grown and to ask them about their perspective on a product that provides them with their livelihood. What would incentivise them to engage in greener practices? And what would that look like? For the latter question, Graihagh speaks to the largest sustainable certifier of palm oil, the RSPO and looks to science to see how we can continue to grow palm oil without having any more adverse effects on wildlife.

This episode is part of the Crossing Divides season which runs from 18 - 24 November. You can find a link to the Food Chain episode below.

Produced and presented by Graihagh Jackson with help from Marijke Peters and editor Rami Tzabar for the BBC World Service.

(Photo: Woman shopping in supermarket Credit: Getty Images)

For decades science fiction has been imagining the incredible ways that machines might interact directly with our minds, from enabling telepathic communication to controlling robotic suits, solely using the power of thought. Getting computers to interface directly with the human brain has proven extremely challenging, but rapidly advancing computer technology is changing the landscape. CrowdScience listener Daniel wonders if we might finally be on the cusp of enabling machines to meld with our minds.

To find out, presenter Alex Lathbridge goes in search of the latest efforts to connect brains to computers. He learns how researchers are combining brain scans with machine learning and gets to test whether an fMRI machine can decode his emotions. He then meets someone with a brain implant but discovers there are many hurdles to overcome before these become mainstream in clinical practice – for example, how can scientists develop implants that won’t damage the brain?

With tech companies like Facebook and Elon Musk’s Neuralink starting to invest in this sector, many experts believe it is only a matter of time before thoughts are ‘readable’. Whilst currently this technology is focussed on helping people with serious medical conditions, other potential applications for it are raising ethical considerations.

Could it be possible to read someone's mind against their will? Might this be used in warfare? Listener Daniel wonders how far this technology might go, leading Alex to ask an ethicist what mind-reading technology might do to society.

Presented by Alex Lathbridge

Produced by Melanie Brown

(Photo: Telepathic people symbols are connected, mind reading as 3D illustration. Credit; Getty Images)

We’re all familiar with the sensation of sleepiness – heavy eye-lid, that warm, fuzzy feeling. But, one CrowdScience listener wants to know, what’s actually going on in our body and brain when tiredness takes over?

Presenter Marnie Chesterton takes up the challenge and follows a trail that leads to circadian scientists working at the NASA Ames research centre in Silicon Valley. It turns out aviators and astronauts take sleepiness very seriously indeed.

Marnie sends out roving reporter Anand Jagatia to investigate how our psycho-motor skills are affected by fatigue in a driving simulator. And we ask how does sleepiness change with age? Why, when tired, do adults crave a nap but children become ever more excitable? And what the hell’s going on with teenagers? We have some answers.

Presented by Anand Jagatia

Produced by Dom Byrne

(Photo: Tired woman taking a nap at work sitting at office desk. Credit: Getty Images)

Most of us take the ability to speak fluently for granted, but for listener Breeda it has been a lifelong struggle. She has asked CrowdScience to investigate whether there is a cure for stuttering and, if not, what the best way to live with it is. Breeda is not alone, as stammering is a neurological condition that affects 70 million people worldwide.

The CrowdScience team head to Oslo in Norway to follow a group of young people who have signed up for a highly disciplined and potentially life-changing training course. The first milestone is to learn to say their name without a stutter. For many, this is a huge challenge that triggers years of distress and anxiety.

With hundreds of muscles and many parts of the brain being involved, speaking is one of the most complex tasks that humans perform. Scientists have discovered subtle differences in the insulation surrounding nerve cells, so-called myelin, between people who stutter and those who don’t. This irregularity may be the source of a tiny time delay in signals between crucial regions of the brain that need to work closely together to produce speech. In the future, it may be possible to stimulate certain brain areas to boost growth and connectivity.

Presenter: Gareth Barlow

Produced by Louisa Field for the BBC World Service

(Image: Illustration of humans speaking with quotation marks, credit: Getty Images)

Crowdscience listeners Michael and Ricky have been walking a tributary of the River Thames in London, UK. They’ve noticed that there are loads of fish, which have only returned in recent years thanks to clean water initiatives. But what about salmon, they wonder? Could they one day return too? If they popped some salmon eggs in the river, would they return to spawn later on in their lives?

Marnie Chesterton heads to Norway to find out whether it’s possible. There, she follows the life cycle of salmon, from birth to death and travels to the salmon’s spawning grounds, before following their path out to sea and beyond. She explores the science behind ‘natal homing’ - returning to the place of your birth in order to reproduce. It isn’t just confined to salmon. But how does it work? Marnie also learns to fish as she joins an active research project that's evaluating if escaped farmed salmon are threatening their wild counterparts by interbreeding. Could this stop salmon swimming home?

Back in the UK, Marnie finds out if all this Norwegian expertise could be transplanted to a river in London? Quite possibly, but it's not without its challenges, as the UK's Environmental Agency found out after attempting to re-introduce salmon into the River Thames.

Presenter: Marnie Chesterton

Produced by Graihagh Jackson for the BBC World Service

(Photo: The mighty Wild Atlantic salmon travelling to spawning grounds in the Scottish highlands. Credit: Getty Images)

Faced with one cake and eight hungry people, it’s pretty obvious how maths underpins reality. But as mathematics gets further from common sense and into seemingly abstract territory, nature still seems to obey its rules - whether in the orbit of a planet, the number of petals on a flower, or the structure of an atom.

But what exactly is the relationship between mathematics and reality? That’s the impossibly difficult question CrowdScience has been set this week by our listener Sergio in Peru. It’s one that’s been pondered by humans for millennia: the Greek philosopher Pythagoras believed “All is number”.

Is maths a human construct to help us make sense of reality - a tool, a model, a language? Does maths create its own reality? Or is it reality itself?

CrowdScience explores these questions with the help of experts from the fields of philosophy, mathematics and science: Dr Eleanor Knox, Dr Eugenia Cheng, Professor Lucie Green, Alex Bellos and Stefano Centineo.

Presenter: Marnie Chesterton

Produced by Cathy Edwards for the BBC World Service

(Photo: A young woman with her eyes closed standing in front of chalkboard, working out maths formulas. Credit: Getty Images)