CrowdScience

What is light and can we trap it in a box? On this edition of CrowdScience, Marnie Chesterton brings you a kaleidoscope of colourful questions from listeners around the world, from Kampala to Chicago. Shireen asks why people have a favourite colour and whether other animals show colour preferences too. Marnie heads to the zoo to see what the birds, bees and butterflies think. There, she meets a colour-changing chameleon to find out how and why it does because of a question from Dramadri in Uganda.

Meanwhile, Paul in Melbourne is interested to know more about colour blindness. And finally, Feroze asks why we only see a portion of the electromagnetic spectrum and wants to know if we might, one day, hack our vision to see beyond the seven colours of the rainbow.

Presenter: Marnie Chesterton

Producer: Graihagh Jackson

(Photo: Stardust and magic in a woman hands on a dark background. Credit: Getty Images)

Hedgehogs are the UK’s favourite British mammal. They have cute furry faces, a snuffly nose and the ability to gobble up garden slugs. What’s not to like? Answer: quite a lot if you live in the Outer Hebrides. Hedgehogs were introduced to South Uist in the 1970s as garden pest controllers, but are now serious pests in their own right – munching their way through the eggs and chicks of globally important wading bird populations. This emblem of cuteness is really a killer. So what’s to be done?

That’s the quandary facing this week’s CrowdScience thanks to a question from Juan Carlos in Cuba. He wants to know how different parts of the world are dealing with invasive species – one of the biggest threats to global biodiversity. Presenter Anand Jagatia heads to the Uists to hear how having an invader that’s loved by millions can cause a whole host of problems. He also discovers how various warring parties eventually came together to solve this very prickly problem.

Also in the programme, Anand travels to South Africa to find out how researchers are coping with invasive trees by introducing another non-native species. While in the Caribbean, we hear how people are dealing with invasive fish by eating them.

Presenter: Anand Jagatia

Producer: Anna Lacey

(Photo: A European hedgehog. Credit: Getty Images)

Teenagers are known for ignoring their parents’ advice, but is this reputation for rebellion well-founded? If so, is rejecting the advice of previous generations and treading our own path an important part of what it means to be human? Are we successful as a species precisely because of our questioning natures?

Listener Hans started pondering these questions after his own adolescent children repeatedly ignored his nagging. Many animals simply follow in their parents’ footsteps – so what makes human children different?

Marnie Chesterton and a panel of experts look at the science of taking advice and making decisions, finding out how human curiosity and exploration compare to other animals, learning the best ways to give and take advice, and seeing whether we’re more likely to trust artificial intelligence than the wisdom of our elders. Finally, we give listener Hans some expert advice on whether or not to keep nagging his kids.

Presenter: Marnie Chesterton

Producer: Cathy Edwards

(Image: A father and son having communication issues. Credit: Getty Images)

This deceptively simple question from listeners Andy, Mike and James is actually one of the hardest questions CrowdScience has ever tackled. Why? Because even scientists struggle to explain the true nature of the magnetic force and to do so in a way that even presenter Marnie Chesterton can understand is a serious challenge. What is a magnet? And just what is going on when magnets exert a force?

With the help of Melanie Windridge, Sean Giblin, Steve Bramwell, Charlotte New and Peter Morris we attempt to navigate the oddities of one of the most fundamental phenomena in the universe.

(Image: A horseshoe magnet attracting some hammer nails. Credit: Getty Images)

Anand Jagatia heads to the rainbow nation of South Africa, to answer listener Lucy’s deceptively simple question. He follows the path of early human migration to understand the relationship between light skin and latitude, and find out how the world become more multi-coloured as people ventured further away from the equator. And he learns how our genes have helped us adapt to less sunny environments, hearing from the remote KhoeSan tribe in the Kalahari desert, who took part in a massive study aimed at giving scientists a better understanding of pigmentation.

Producer: Marijke Peters

Presenter: Anand Jagatia

(Image: Four diverse women’s arms holding each others wrists in a circle. Credit: Getty Images)

Listener Pogo wants to know why there aren’t any cabbages – or any of the other vegetables – in his local forest. Where did they all come from? And could they someday disappear? Presenter Gareth Barlow goes hunting for wild snacks in a city park and unearths the evolution of our most beloved greens. The vegetables on our supermarket shelves today were not always nicely wrapped and tasty. Humans have been selecting for specific genes in plants for thousands of years by choosing to grow those we liked the most.

Tomatoes have been transformed from a small prickly desert plant in Peru into a water guzzler with round, juicy, sweet fruits. But with breeding – and sometimes cloning – of plants we have also created genetic bottlenecks in many of the crops we rely heavily on. This has left many of our vegetables across the world vulnerable to shifts in climate, natural disasters, wars and diseases.

To find solutions to this massive breach in food security, CrowdScience heads to the Millennium Seed-bank in England. By collecting and storing our most precious seeds in vaults beneath the ground, scientists are protecting the genetic diversity that we will need to overcome the challenges ahead.

Presenter: Gareth Barlow

Producer: Louisa Field

Picture: Man holding basket of vegetables

Credit: Getty Images/valentinrussanov

Sex – for most organisms - is about meeting the right partner. But what if you and your mate are stuck far apart with no ability to travel? This dilemma could put a bit of a downer on your sex life, but is faced by plants everywhere. Presenter Anand Jagatia uncovers the happy fact that not only have plants overcome this problem, they positively excel at it. From hay fever to honey, the sexual strategies of plants affect us daily, and we couldn’t live without their success. In this episode, CrowdScience is answering the questions you sent after a previous episode entitled ‘Can plants talk?’ which explored the way plants and trees use a fungal network to communicate. This time, we explore how plants ‘feel’ bees as they fly past, and more complex communication involving the ‘wood wide web’.

Presenter Anand Jagatia

Producer: Rory Galloway

(Image: A yellow dandelion flower attracts a pollinator in the evening sunlight. Credit: Getty Images)

Some of the biggest reserves of freshwater are right under our feet and they're really important for farming as well as providing us with water to drink. However, in some areas of the world, groundwater is being slurped up quicker than it can be replenished. In fact, about 1.7 billion people live in regions where groundwater is under stress, 60% of them in India and China. This figure is set to rise as the climate changes and as the population grows.

CrowdScience listener Waheed from Afghanistan wants to know if we will run out of groundwater and what the repercussions might be. Marnie Chesterton trots around the globe to find out, starting with a row on the River Thames before hearing from Afghanistan to understand what’s happening where Waheed lives. She learns of what has happened to London, Mexico and Malta when they over pumped their aquifers. Finally, Marnie looks to Bangalore where the population is booming to understand how they’re coping with increasing demands on water.

Presenter: Marnie Chesterton

Producer: Graihagh Jackson

(Image: Children holding their hands up - asking for drinking water. Credit: Getty Images)

What sounds heavenly to one person might sound like boring noise to another - but why are our musical preferences so different? Is it all down to what we hear growing up, or are other factors at play?

CrowdScience listener and music lover Jocelyne from Canada wants to know why she has a different song for every mood, and why she likes different music from her friends and family.

Meanwhile in Italy, composer Elisabetta Brusa asks us whether the rules of harmony align with the laws of science, and should therefore not be broken.

We talk to both musicians and neuroscientists to explore the truth about harmony and discord. We find out how age, personality and experience all affect whether we find certain songs pleasing or offensive, and learn why the search for the true universals of music pleasure is a race against time.

Presenter: Marnie Chesterton

Producer: Cathy Edwards

(Image: A couple laying in the grass listening to music on headphones. Credit: Getty Images)

Hypnosis has a long and controversial history, with its roots in animal magnetism or mesmerism, the theory developed by 18th Century German doctor Franz Mesmer. He believed he had discovered an invisible natural force possessed by all living things, and that he could channel this force for healing purposes.

Popularity of hypnosis has since waxed and waned, but was largely denounced as quackery until the 20th Century, when it began to be studied scientifically. However it is only in the last twenty years or so that is has become incorporated into mainstream science and medicine.

But is it a real phenomenon, asks listener Gratian from Poland; and Anton from Ireland wants to know how it works and what happens to people’s brains and bodies under hypnosis?

CrowdScience speaks to Dr Quinton Deeley, consultant psychiatrist and senior lecturer at the Institute of Psychiatry, who has used it in practice for many years, and Dr Amir Raz, a magician-turned-neuroscientist who is shedding light on how hypnosis works. To see how hypnosis is being used clinically, CrowdScience visits the Berkeley Clinic in Glasgow, Scotland, to witness a hypnotised patient having a tooth extracted with very little anaesthesia.

Meanwhile, presenter and self-confessed arachnophobe Nastaran Tavakoli-Far takes part in the Friendly Spider programme at London Zoo, an afternoon event that uses hypnotherapy and group therapy to ease or eliminate the fear of spiders.

Presenter: Nastaran Tavakoli-Far

Producer: Helena Selby

(Image: A silver pocket watch swinging on a chain on a black background to hypnotize. Credit: Getty Images)