There are over 7000 living languages on earth today. These mutually unintelligible means of communication are closely associated with different groups' identities. But how does a new language start out? That’s what listener BK wants to know. BK lives on one of the islands of the Philippines, where he speaks three languages fluently and has noticed there is a different language on almost every island.

Presented by Anand Jagatia,

(Photo: Chalk board of languages, Credit: Getty Images)

Despite being a universal need, talking about our toilet use and the infrastructure that aids us remains somewhat taboo. Whilst sectors like telecommunications and computing have undergone rapid transformations over the past century, the flush toilet and wastewater system have mostly remained unchanged.

CrowdScience listeners Linda and Allison wonder if flush toilets – and the clean water used to wash waste away - make economic or environmental sense. So CrowdScience presenter Marnie Chesterton looks under the toilet lid, to probe (in a sanitary fashion) whether our sewerage systems and plumbed toilets are fit for purpose. In a future where population growth and climate change are likely to affect water demands, can we continue to use clean water to dispose of our waste and should the developing world be emulating this model?

Around 2 billion people don’t have access to proper toilets or latrines, risking serious health consequences. Marnie investigates how countries without comprehensive sewerage infrastructure deal with human waste and how science is providing novel ways to dispose of - and use – human waste. Marnie speaks to a Kenyan scientist using poo-eating fly larvae to process faeces and a North American scientist who is developing a smart-toilet she hopes will monitor our health through sampling our daily movements. Are we ready to break taboos to innovate our toilet habits?

Presenter: Marnie Chesterton

(Image: Man looking at toilet. Credit: Getty Images)

What is the smallest particle of matter? How does radiation affect our bodies? And, how is particle physics useful in our everyday lives?

CrowdScience takes on particle physics questions from listeners all over the world. Marnie Chesterton and Anand Jagatia get help from particle physicists from the Large Hadron Collider at CERN and medical physicist Heather Williams.

Presented by Marnie Chesterton and Anand Jagatia

(Photo: Particle collider, Credit: Getty IMages)

What’s the importance of zero, and how was it discovered? How do scientists calculate Pi’s infinite digits? Why do so many people find maths difficult – and what’s the most difficult thing in maths?

CrowdScience takes on a whole bunch of questions sent in by high school students in Spain. Like many children all over the world, their school is currently closed due to the coronavirus lockdown, but lessons continue at home. So how are their studies going, and can CrowdScience help out?

We attempt to answer some of their trickiest maths questions, with the help of mathematicians Katie Steckles and Matt Parker, and mathematical biologist Kit Yates.

Presenter: Marnie Chesterton.

Producer: Cathy Edwards

(Photo: A boy studying. Credit: Getty Images)

If you're an exercise fan, you'll know that sweating is how our bodies keep us cool, but how much water we lose and which bits of us get wettest depend on a whole host of factors.

Jamaican listener Andre wants to know why he sweats in a heart-shape when he hits the gym, and we find out how everything from the clothes he wears to the moves he's doing explain his unusual perspiration patterns.

In Kenya we meet a woman whose permanently clammy hands cause her to drop her mobile phone, and sweaty feet start to stink when she spends too long in shoes.

Hyperhidrosis is a condition affecting millions of people worldwide but an expert explains some of the treatments for this mysterious condition.

Presenter: Marnie Chesterton

Image Credit: Getty Images

If you have ever watched a spider as it works to build a web, spiralling inwards with a thread of silk, that intersects each glistening spoke with a precise touch of the foot, you will know that it is a remarkably complex behaviour. In this episode, presenter Geoff Marsh dives into the minds of spider-constructors as they build their webs.

Taking us deep under the exoskeletons of invertebrates, Professor Gene Robinson reveals an animal's behaviours can be altered by their genes, and the root similarity between learning and instincts. Spiders, despite their tiny size, have fascinating behaviours. Some jumping spiders can work out the best way out of a maze, and one arachnologist reveals how some social spiders can cooperate to build communal webs and capture moths that are many times their size.

Image: European garden spider, Araneus diadematus hanging in the web. Photo by: Michael Siluk / Universal Images Group via Getty Images

Listener Keith from Lincolnshire wants to know how to reduce stress as he is under extreme pressure as a firefighter. Not only does he have to cope with the stress of responding to emergency situations but he has to do it while wearing challenging breathing equipment.

We all experience times of stress, especially given the current situation, our chest starts to feel tight and our breathing becomes shallow. Claudia Hammond – presenter of BBC World Service programme Health Check – explains steps we can take to protect our mental health during this pandemic.

How should we alter our breathing to manage stress? Presenter Anand Jagatia speaks to breathing experts to find techniques to help listener Keith, and everyone else.

Presented by Anand Jagatia. Produced by Caroline Steel for BBC World Service.

In medicine, it’s long been recognised that a placebo, a sham medicine or treatment, can have a powerful positive effect on a patient’s health. Part of that effect relies on a person’s belief that an inactive substance or treatment (for example, a sugar pill) is in fact an active drug. Placebos come in many forms, and the scientific study of placebo is an active area of research.

Produced by Dom Byrne, presented by Anand Jagatia.

If you've ever felt the urge to shop till you drop, then you may already know about some of the clever ways retailers convince us to consume. From flash sales to so-called unbelievable offers, there are a whole range of techniques aimed at encouraging us to flash the cash. Listener Mo works in marketing, so knows more than most about the tricks of the trade - but he wants CrowdScience to investigate how neuroscience is being used to measure our behaviour and predict what we’ll buy. Marnie Chesterton finds out how brain scans are being used to discover which specific aspect of an advertisement a person is responding to, and then she hears how this information is being used by companies who want to sell us more stuff. But there's also evidence to suggest we have less control over these decisions than we think, and that computers are getting closer to detecting our intention before we're even aware of it ourselves. And this could have huge implications for the way we shop.

Presented by: Marnie Chesterton

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Many of us are fascinated by our ancestry: knowing where our families came from can give us a sense of identity and roots. Tracing your family tree is a time-honoured tradition, but several companies now sell DNA tests that offer you insights into your heritage: so you might find out you’re 70% Nigerian, 39% Italian, or 11% South Asian, for example.

There’s no doubt that genes contain clues about your family history, but how reliable are these commercial tests? That’s what CrowdScience listener Karen wondered after an update of her test results showed her going from 39% Scandinavian to 2% Norwegian. How confident can she be in her results now? And what does it actually mean to be 2% Norwegian, in terms of your family tree?

Presenter Alex Lathbridge delves into his own African and European ancestry, talks to some of the companies offering these tests, and unpicks the complex relationship between genetic science and family trees. We meet a woman who found her long-lost uncle with a combination of a DNA test and old-fashioned archive research; and look to the Americas to ask whether genetic testing can restore ancestral ties erased by the inhumanity of the transatlantic slave trade.

(Photo: Elderly hands looking at old photos of self and family. Credit: Getty Images)