Would you willingly break a mirror, walk under a ladder or cut up an image of someone you love - or might you be worried about tempting fate – even if you don’t believe in supernatural forces? 
 
Anand Jagatia enters the world of magical thinking on behalf of CrowdScience listeners to explore why - even in this era of scientific rationalism – superstition, magic and belief in concepts like the evil eye and luck appear deeply entrenched in our cultures and psyche.
 
Meeting historians and psychologists, Anand sets out to reveal the enduring lure of superstition and explore the biological factors that can influence us, like how our brains have evolved to look for connections and find patterns in seemingly random events. 
 
Is it possible that some people are ‘lucky’ and can we enhance our own ‘luck’? Experimental evidence is thin on the ground but finger’s crossed, CrowdScience can find some.
 
Presenter: Anand Jagatia
Producer: Melanie Brown (Image: A handmade Voodoo Doll with pins. Getty Images)

What Makes Us Superstitious?

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When CrowdScience listener Israel from Papua New Guinea received a bad grade on a maths test in third grade, he looked around the class and realised that almost all the other students had received a better result. Since then, he has always wondered: why are some people better at maths than others? 
 
And Israel isn’t the only one to think about this: our listeners from all over the world describe their relationships with numbers, which run the full gamut from love to hate.  
  
So are we all in control of our own mathematical fate, or are some people just naturally bad at it? Presenter Anand Jagatia hears about studies of identical and non-identical twins showing how genetics and environment interact to shape our mathematical abilities. 
  
Our numerical abilities are not set in stone. It’s always possible to improve, and getting rid of negative feelings and anxiety around maths could be the key, says psychologist Iro Xenidou-Dervou. 
 
Some countries seem to support children’s maths skills better than others. China and Finland both rank highly in international league tables; education experts in both countries discuss whether there are any keys to a successful mathematics education. 
  
And there is something underlying our ability to do maths in the first place: our number sense. We hear what happens when this number sense does not work as intended – and what can be done about it.  
  
Contributors: 
Professor Yulia Kovas – Goldsmiths University of London, UK 
Professor Pekka Räsänen – University of Turku, Finland 
Assistant Professor Zhenzhen Miao – Jiangxi Normal University, China 
Dr Iro Xenidou-Dervou – Loughborough University, UK 
Professor Brian Butterworth – University College London, UK 
 
Presented by Anand Jagatia 
Produced by Florian Bohr 
Editor: Cathy Edwards  
Production Co-ordinator: Liz Tuohy  
Studio Manager: Jackie Margerum  (Photo: Boy scratching head in front of blackboard. Credit: Jose Luis Pelaez Inc/Getty Images)

Why am I bad at maths?

Coastlines around the world are changing, causing serious problems for the many communities living near the sea, as well as vital and fragile coastal ecosystems.  In the second of a two-part special on coastal erosion, CrowdScience explores the best ways to tackle this problem. Presenter Caroline Steel visits the Caribbean island of Puerto Rico to see the various methods they use to protect their coasts.  First up: ‘riprap’ – rocks strategically placed to keep the encroaching sea at bay. The problem is, while it protects the area immediately behind the rocks, riprap can exacerbate erosion nearby.   But there are other, more nature-friendly solutions, including sand dune restoration. Caroline picks up her shovel and helps to re-plant dunes, destroyed in the past by erosion as well as sand extraction for the construction trade. The roots of these plants stabilise the dunes, while building boardwalks prevents further damage from humans.   Nature also offers the perfect offshore protection against coastal erosion: coral reefs. These are the first line of defence in absorbing the power of the ocean’s waves. Down on the beach, we see for ourselves just how effective they are. The reefs face threats, but restoration plans are afoot. We visit a nursery that grows corals to plant out on the reefs – and find out about corals’ surprising cannibalistic tendencies in the process.  Featuring: 
Professor Robert Mayer - Director of Vida Marina, Center for Conservation and Ecological Restoration, University of Puerto Rico 
Nada Nigaglioni - Biology student, University of Puerto Rico  
Ernesto Diaz - Caribbean Regional Manager at TetraTech 
Dr Stacey Williams - Executive Director, ISER Caribe  Presenter: Caroline Steel 
Producer: Hannah Fisher 
Editor: Cathy Edwards 
Production Co-ordinator: Liz Tuohy 
Studio Manager: Emma Harth (Photo: Coast restoration measures at Ultimo Trolley Beach, Puerto Rico. Credit: BBC)

How should we protect our coastlines?

Around the world, coastlines are constantly changing due to the power of waves, currents and tides. Coastal areas are also some of the most heavily populated and developed land areas in the world. So it’s not hard to see how the natural process of coastal erosion can cause serious problems for us.    It’s an issue that’s been bothering CrowdScience listener Anne in Miami Beach, Florida. She can see the beach from her window and wonders why after every storm, several trucks arrive to dump more sand on it.   In this first of two programmes, CrowdScience visits Anne’s home in south Florida and finds out how erosion threatens Florida’s famous beaches. Caroline Steel speaks to geoscientist Dr Tiffany Roberts Briggs and hears why it’s such a problem for this tourist-reliant state. Tiffany explains the delicate balance between natural processes and human infrastructure.   Meanwhile, the Caribbean island of Puerto Rico declared a state of emergency in April 2023 due to coastal erosion. Caroline witnesses the impacts of erosion first-hand, as Ruperto Chaparro shows her abandoned houses crumbling into the sea.   But how can we quantify the rate of erosion? Dr Kevian Perez in the Graduate School of Planning at University of Puerto Rico explains the methods they use to monitor Puerto Rico’s coastlines, and how they are evaluating the effectiveness of different mitigation methods.   However, some of the methods used to protect coastal communities from the encroaching sea have done more harm than good. So what are the best ways to tackle this problem? That’s what we’ll be exploring in next week’s programme.   Presenter: Caroline Steel 
Producer: Hannah Fisher 
Editor: Cathy Edwards 
Production Co-ordinator: Liz Tuohy  
Studio Manager: Steve Greenwood and Bob Nettles  Featuring: 
Dr Tiffany Roberts Briggs, Associate Professor at Florida Atlantic University 
Ruperto Chaparro, Director of Sea Grant Programme, University of Puerto Rico 
Anabela Fuentes Garcia, Villa Cristiana community leader 
Dr Kevian Perez, researcher at the Coastal Research and Planning Institute of Puerto Rico at the Graduate School of Planning (Photo: Puerto Rico after Hurricane Maria. Credit: Orlando Sentinel/Getty Images)

Are our coastlines being washed away?

How do we know where a sound is coming from?  Another chance to hear this ear-opening episode, exploring a question from CrowdScience listener Chiletso. One day, he heard his son bounce a ball and instantly knew the direction it was travelling. How?  Anand Jagatia sets out to discover what makes left, right, up and down sound so different.  First, he gets blindfolded, so Alan Archer-Boyd, former auditory scientist and lead engineer at BBC R&D;, can put his sound localisation skills to the test. It turns out that having two ears and pinnae, those flappy bits of cartilage on the side of your head, help a lot.  Professor Eric Knudsen shares how the barn owl’s asymmetrical ears allow it to hunt mice, even in complete darkness.  And Anand uncovers how far he can push his own spatial hearing. Blind activist and researcher Thomas Tajo teaches him how to echolocate like a bat, and Dr Lore Thaler explains what is going on in the brain of experienced echolocators.  This programme was originally broadcast in March 2023.  Presented by Anand Jagatia 
Produced by Florian Bohr for the BBC World Service  Image: Boy with hands at his ears 
Credit: Silke Woweries/Getty Images

How do my ears sense direction?

Today there are over eight billion people on Earth. That’s an awe-inspiring figure… but how does it compare to the vast numbers who came before us? Listener Alpha wants to know how many people have ever existed, so CrowdScience sets out to do a historical headcount. The Population Reference Bureau in the USA estimated this number back in the 90s, and have been updating their calculations ever since. Demographer Toshiko Kaneda explains how their model works, the assumptions it makes – and the huge uncertainties around the number it comes out with. We first need a date for when ‘humans’ first began, so Caroline travels to the Natural History Museum in London to meet human evolution expert Chris Stringer, and marvel at his collection of replica fossil skulls. Chris demonstrates how to distinguish our species, Homo sapiens, from other species like Neanderthals. When did these species first appear - and which of them count as human? And once you know where to start the clock, how do you estimate the numbers of people alive at different points in history? For a population demographer like Walter Scheidel, it helps that some ancient civilisations kept detailed censuses, a few of which have survived to the present day. Caroline and Walter pour over one of these census fragments, and learn how to combine them with other archaeological clues to get some very rough numbers. And finally: what does the future of our population look like? Poonam Muttreja from the Population Foundation of India discusses developments in the world’s most populous country, as well as the big demographic trends ahead for humanity.  Presenter: Caroline Steel 
Producer: Phil Sansom 
Additional Recording: Umaru Fofana 
Editor: Cathy Edwards 
Production Co-ordinator: Connor Morgans 
Studio Manager: Sue Maillot  Featuring:
Toshiko Kaneda, Technical Director of Demographic Research, Population Reference Bureau
Chris Stringer, Research Leader in Human Evolution, Natural History Museum London 
Walter Scheidel, Professor of Classics and History, Stanford University 
Poonam Muttreja, Executive Director, Population Foundation of India

What Makes Us Superstitious?

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