Explorations in the world of science.
The Zedonk Problem
Today I learnt that tigons and ligers are what you get when lions and tigers interbreed?!’ surprised listener Jamz G tells the doctors. ‘What determines whether species can interbreed?’
Geneticist Aoife McLysaght studies molecular evolution. She explains the modern definition of a species, built on ideas from Aristotle, Linnaeus and Darwin: a species is a group of organisms capable of interbreeding to produce fertile offspring. Hybrids – such as ligons and tigers – are usually infertile, because their common ancestors long ago diverged into the lions and tigers we know today. However, this definition isn’t absolute, and there are many ways a new species can be formed.
Hybrids also offer rich study subjects for scientists. Mathematical biologist Kit Yates discusses why he’s been reading research papers about hebras and zorses (horse x zebra) as their patterns offer insights into how cells spread and develop into organisms, building on a prediction made by codebreaking mathematician Alan Turing.
And it turns out that these hybrids are even more intriguing. As speciation and evolution expert Joana Meier explains, hybrids are not always infertile. Hybridisation can lead to successful new species arising, such as in Lake Victoria’s cichlid fish, who it seems have been having a wild evolutionary party for the last 15,000 years. And the picture gets even murkier when we discover that modern genetics reveals our human ancestors successfully mated with Neanderthals.
Presenters: Hannah Fry & Adam Rutherford
Producer: Jen Whyntie
The Evidence: Pandemic rules: follower or flouter?
Millions of us, across the world, are subject to curfews, stay-at-home orders and lockdowns but what makes us stick to the rules, bend them or ignore them altogether? Claudia Hammond and her expert panel of guests consider the psychology of following the rules.
Leading social psychologists share research which show that higher levels of trust in leadership translates to more pandemic guidance followed. A sense of “We” not “I”, a shared identity, makes a difference too, as well as identification with the whole of humankind, not just your immediate family.
But there is danger too, from a “narrative of blame”, where individuals are demonised if they break the rules. Such an approach, Claudia hears, is corrosive to the all-important sense of shared identity and alienates some groups, while making others complacent.
Also in the programme, what impact can rapid “have you got it” antigen tests which give results in minutes, rather than days, have on the virus?
Claudia hears from the Cameroon in Central, West Africa, one of the first countries in the world to try mass testing using these rapid diagnostic tests. And she talks to scientists at the forefront of evaluating and modelling how their use could affect transmission of the virus, and daily life for all of us, until a vaccine is available.
This month, Claudia’s panel of specialists answers BBC World Service listeners’ questions and includes Professor Michael Mina, Assistant Professor of Epidemiology Immunology and Infectious Diseases at Harvard TH Chan School of Public Health in USA, Dr Margaret Harris, from the World Health Organisation in Geneva, Switzerland, Steve Reicher, Professor of Social Psychology at St Andrews University in Scotland, Professor Rolf Van Dick, social psychologist and Vice President of the Goethe University in Frankfurt, Germany and Dr Jilian Sacks, senior scientific officer for Pandemic Preparedness for FIND, the Foundation for Innovative New Diagnostics in Geneva.
The end of everything
Everyone knows about the Big Bang being the beginning of the universe and time - but when and how is it going to end? ask brothers Raffie and Xe from Rome. For this series, with lockdown learning in mind, Drs Rutherford and Fry are investigating scientific mysteries for students of all ages. The doctors sift science from philosophy to find out.
Cosmologist Jo Dunkley studies the origins and evolution of the universe. She explains how astrophysical ideas and techniques have evolved to tell us what we now know about our galaxy and far beyond, from the elegant parallax technique to standard candles. This particular distance measure, which uses stars of a known brightness to work out how far away other objects in the universe are, was discovered by American astronomer Henrietta Swan Leavitt in 1912, who worked at the Harvard University as one of several “computers” – women who processed and calculated data and made significant contributions to astronomy.
Curious Cases’ universal guru Andrew Pontzen puts this into context. Because the universe is so enormous, it turns out that these measurements are just the first steps on the cosmic distance ladder – a suite of tools that astrophysicists use to determine distances to celestial objects. Scientists know that objects are moving away from us because the wavelengths of light from them get stretched and appear redder in our telescopes – the so-called red shift effect. But having a handle on the distances to and between those objects allows cosmologists to monitor what’s happening to them over time. And it turns out that not only are they getting further apart, indicating that the universe is expanding, but that this process is accelerating.
So what might happen in the end? Expansion and then collapse – a big crunch? Expansion into the void – a big freeze, or a big rip? Or what if there is more than one universe – might a new one bubble up with totally different laws of physics that would cause our own to cease existing? It turns out that when dealing with predictions for something involving infinite space and time, the possibilities are largely limited by human imagination alone. Ideas are where science starts, but experiments are required to build evidence confirming or rejecting them as fact. The doctors discuss how gravitational wave detectors and quantum computers might one day provide this.
Presenters: Hannah Fry & Adam Rutherford
Producer: Jen Whyntie
Autism is a lifelong condition, often seen as particularly ‘male’. Yet a growing number of women, and those assigned female at birth, are being diagnosed as autistic in their 30s, 40s, 50s, and beyond. Writer and performer Helen Keen is one of them, and she’s found this diagnosis has helped her make sense of many aspects of her life, from growing up with selective mutism, to struggling to fit in as a young adult. In this programme Helen asks why she, like a growing number of others, had to wait till she was well into adulthood before finding her place on the autistic spectrum. She discovers that for many years psychologists believed that autism was rarely seen in women and non-binary people. Now it is accepted that people often display autistic traits in different way - for example, they may learn to ‘camouflage’ and behave in a neurotypical way - but at what cost? Helen talks to others like her who have had late diagnoses, and finds out if knowing they are on the autistic spectrum has given them insight into how they can navigate the pressures on them from contemporary society. She also explores how we can value and celebrate neurodiversity.
Helen also talks to psychologists Professor Francesca Happé, of the Institute of Psychiatry, Psychology and Neuroscience in London, and Dr Steven Stagg of Anglia Ruskin University about their research into autism.
Picture: Geometric camouflage pattern, Credit: Yuri Parmenov/Getty Images
Birds: singing for survival
As large areas of the world have locked down this year, many of us have become more aware of the birdsong around us. The relative silence has allowed us to listen in. But scientists have known for several years that the birds themselves have been responding to human noise too, by pitching their songs and other calls higher, to be heard over the rumble of our urban life.
There are several ways in which birds can adapt how they communicate in the face of environmental pressures, but what are the limits to these adaptations? And what can this tell us about how to maximise conservation efforts in the future? Rory Crawford talks to ornithologists and animal behaviourists studying bird species around the world. He finds out how the advance of technology is helping researchers explore birds’ preferences and behaviours in the wild, and hears how one particular bird changed its song, and the new version rapidly spread across North America – “the most viral tweet of all time”, as it’s been called!
Picture: A Robin [Erithacus rubecula], Credit: Gary Chalker/Getty Images
Claudia Hammond asks if touch can be replicated digitally? What devices exist already and how likely are we to use them?
Michael Banissy, co-creator of the Touch Test, neuroscientist David Eagleman and researcher Carey Jewitt look at the possibilities for touch technologies in the future. David has developed a wristband that translates sound into touch for deaf people, Carey looks at the ethics of digital touch and Michael reveals the attitudes from the Touch Test towards digital technologies. If we could replicate the feeling of holding a loved one's hand in hospital would it really be the same? And dancer Lisa May Thomas talks about her experience of extending touch into space and through virtual reality.
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Excellent Way To Learn
They review so diverse matters on a frendly way, so, it can be listened and learn without having to be an expert on all those many fields.