CrowdScience

“You are what you eat” is a well-known saying. But is it really true? That’s what we explore in this week’s CrowdScience thanks to a question from listener Claire from Australia.

We each have trillions of tiny microbes and bacteria inside our bodies, living in our mouths, skin, ears and even in our eyes. Each community of microbes and bacteria is known as a microbiome. The most populous of these is in our gut, with hundreds of trillions of organisms and bacteria helping digest the food we eat.

Our gut microbiome is affected by lots of things but mainly by our diet. With our gut microbiome forming such a massive part of our insides, people have long suspected that what we eat impacts how we feel.

Presenter Caroline Steel investigates. She speaks to a professor of Psychiatry, Jane Foster, to find out how interconnected our microbiome and our brain really are. Professor Foster also explains the different ways in which our microbiome and brain communicate.

Do we really know what role diet plays in mental health? Consultant psychiatrist Professor David Veale provides more detail. And at a café with a rather interesting menu, Caroline samples some of the food available as occupational therapist Joel Oliver explains how important food can be as part of mental health treatment.

This begs the question: if our microbiome really does influence our mental health, can we harness the power of microbes to potentially find new treatments to help our mental health? Dr Najaf Amin tells us about her research identifying the link between specific microbes and depression.

Producer: Hannah Fisher Presenter: Caroline Steel Editor: Richard Collings Production Coordinator: Jonathan Harris Studio Manager: Bob Nettles

(Photo: Young hipster man eating salad. Credit: Tara Moore / Getty Images)

Our bodies are made of cells, tens of trillions of cells. They all have particular roles and functions in the body, from digesting food, to producing hair, to hunting down pathogens. But all of this incredible complexity started as just a single cell.

Gila, from Israel, asked CrowdScience to find out how the development of incredible structures, and systems in the body are coordinated by the cells. Are cells communicating? How do cells know what they should be doing?

To find out, Geoff Marsh meets a Cambridge researcher uncovering the first cell division in our lives, and peers into a fertile chicken egg to see the developing embryo as it grows a limb. CrowdScience finds out why scientists like Dr Megan Davey use chickens to understand the development of human fingers and investigates how individual cells with the same DNA manage to choreograph a dance of cell replication, movement and communication to create our bodies in all of their complexity.

Presenter: Geoff Marsh Producer: Rory Galloway

(Photo: Cells grouped together. Credit: Getty Images)

When CrowdScience listener, Grady, crashed violently on his motorbike in the desert, he thought he was going to die. Years later he still can’t remember the dramatic seconds just before the impact. Where did the memory disappear to? Did the hard hit to the head knock his memories out or are they still in his brain somewhere? CrowdScience turns to brain science to find out if those last few seconds are lost for good or if the brain tells a different story.

Under normal circumstances our brains like to hold onto memories that are emotionally important to us. We can remember our wedding day but not yesterday’s breakfast. But scientists have discovered that during near-death experiences, our brains are flooded with chemicals that disrupt our ability to remember. Grady may never recall how he was able to keep his motorbike steady as he drove off the road because – maybe – the memory was never created in the first place.

Presenter: Marnie Chesterton Producers: Melanie Brown and Louisa Field Sound design: Eleni Hassabis

(Image: A biker helmet lies on street near to a motorcycle accident. Credit: Getty Images)

Human sexuality comes in many forms, from exclusively heterosexual to exclusively homosexual. But seeing as homosexuality creates apparent reproductive and evolutionary disadvantages, listener Ahmed from Oslo wants to know: why are some people gay?

CrowdScience presenter Caroline Steel examines what science can - and can't - tell us about the role of nature, nurture and evolution in human sexual attraction. She asks a geneticist what we know of the oft-debated 'gay gene', as well as looking into why homosexual men on average have more older brothers than heterosexual men.

Caroline looks into the role of nurture with a developmental psychologist to answer a question from a CrowdScience listener from Myanmar. He wonders if the distant relationship he has with his own father has impacted his own feelings of attraction.

She also learns about research into a group of people in Samoa who may shed light on the benefits of traditionally non-reproductive relationships for communities as a whole.

Presented by Caroline Steel Produced by Jonathan Blackwell for BBC World Service

Contributors: Dr. Kevin Mitchell - Associate Professor of Genetics and Neuroscience, Trinity College Dublin Dr. Malvina Skorska - Postdoctoral Fellow at the Centre for Addiction and Mental Health, Toronto Prof. Lisa Diamond - Professor of Psychology and Gender Studies, University of Utah Prof. Paul Vasey - Professor and Research Chair, Department of Psychology, University of Lethbridge Vaitulia Alatina Ioelu - Chief Executive Officer, Samoa Business Hub

(Photo credit: Ahmed Umar)

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)