Rethink

The US dollar is the backbone of global trade and held by governments around the world as a safe haven in times of crisis.
It's so powerful that countries like Ecuador and Panama have adopted the dollar as their official currency, while Argentina for many years has tried to "dollarize" its economy.
But what happens if nations and private institutions were to lose trust in the dollar?
How did we get here? Well, after WWII the world order was re-established in part by tying the monetary systems to the value of the dollar, backed by gold. But since 1971 President Nixon cut that link to gold and the entire exchange system has since been tied directly to the dollar itself, its historic success and access to its financial markets.
That success gave America what was dubbed an "exorbitant privilege" to print money without fear of inflation and to build up national debt without consequence.
It also enables the US to flex its muscles on the international stage by imposing sanctions on countries and cutting off access to their all-important currency. That has led some countries, most notably China, to call for the dollar to be replaced as the world's reserve currency.
How difficult would it be to untangle the dollar from global trade, can any other nations offer the same conditions which has allowed the US currency to thrive, and what would happen if the dollar's role was replaced by newer digital currencies which operate outside traditional government control?
Presenter: Professor Ben Ansell
Producer: George Dabby
Editor: Damon Rose
Contributors:
Martin Wolf, Chief Economics Commentator at the Financial Times
Barry Eichengreen, Professor of Economics and Political Science at the University of California, Berkeley
David Shrier, Professor of Practice, AI & Innovation with Imperial College Business School
Stephanie Flanders, Head of Economics and Politics at Bloomberg News
Zanny Minton Beddoes, Editor-in-Chief of The Economist
Material from:
British Pathé, "Bretton Woods Money Pact Signed" (1946)

Should we rethink who our city streets are for? It can often feel like there is a hierarchy on the roads, with cars needing to get from A to B as fast as they can, taking priority over people cycling or walking. But what if we flipped it on its head and put pedestrians at the top? Or, what if we saw our streets in a totally new light and instead decided they were places for meeting friends, playing or resting under a tree? Ben Ansell finds the people designing new streets, and he hears one radical idea that requires an entirely new language.
Ben visits a new kind of street where pedestrians have priority, not cars. It has been designed by traffic engineer Keith Firth at NRP. Campaigner Martin Cassini argues we could get rid of traffic lights to encourage drivers to pay better attention to pedestrians and to help ease traffic jams. But would all road users feel confident crossing without a dedicated beep or time to cross? Sohanna Srinivasan, head of Urban Planning Design at North Hertfordshire council, sets out her plan for how streets can have space built-in for people to fully enjoy their neighbourhoods while Dutch author Marco te Brömmelstroet says we need to rethink the language we use about cities. Change the language, change the mind set. Is it that simple?
Presenter: Ben Ansell
Producer: Phoebe Keane
Editor: Damon Rose

Have you ever wondered why some people age better than others?
We all know someone who looks great for their age, and is also in robust health. And yet someone else who is exactly the same age might look older, and may be living with an age-related illness.
Chronological age is not always be a good indicator of how well someone is maturing. So, if our skin - which is our largest organ - suggests how well, or badly, we're aging, then the state of our other organs and the systems that keep them running may also indicate how old we are.
This measure is called your biological age.
And there are many ways of measuring biological age, from the simple - the strength of your hand grip, to the detailed - looking at the changes in chemical markers attached to your DNA, called epigenetic markers.
They lie "on top of" the DNA, without changing it - much like an instruction written on a post-it note attached to a piece of sheet music. The instruction means the music can be expressed differently, without changing the tune. Epigenetics explains why the DNA in every one of our cells is the same, and yet the cells can look very different from one another. They can be heart cells, blood cells, hair cells and so on, because the markers cause different genes on the same DNA to be expressed.
Epigenetics has allowed scientists to create clocks to tell you your biological age: the latest one can even tell you how fast you're aging. Advances in epigenetics have led to the new science of cellular regeneration.
And the world's first clinical trials are underway in the USA for a treatment that transforms old, dysfunctional and damaged cells into young healthy ones - treating aging itself.
Presenter: Ben Ansell
Producer: Ravi Naik
Editor: Damon Rose
Contributors:
Andrew Steele PhD, author of Ageless: The New Science of Getting Older Without Getting Old. and director of the Longevity Initative
Dr Nessa Carey, molecular biologist, visiting Professor at Imperial College London and author of The Epigenetics Revolution
Dr Daniel Belsky, Associate Professor of Epidemiology in the Robert N. Butler Columbia Aging Center, and developer of the algorithm for the DunedinPACE epigenetic clock
Dr Sharon Rosenzweig-Lipson, Chief Scientific Officer at cellular rejuvenation company Life Biosciences

Of the 195 widely-recognized sovereign countries in the world, only a quarter are monarchies.
And of those 43 monarchies, 15 of those have the same King. That’s Charles III, who’s head of state for Commonwealth territories as large as Australia and Canada, and as far apart as the UK and Tuvalu in the South Pacific.
In the other 28, the ruling monarchs can be called Kings, Emirs, Sultans, and there’s an Emperor on the Chrysanthemum throne in Japan.
Of course, there are also Queens - but some modern monarchies such as Japan and Lichtenstein still don’t allow female succession. In others, eldest daughters are passed over for their younger brothers - and this still happens in Spain and Monaco.
If this all seems a bit medieval, that's because it is! Monarchy is a system of governance that developed hundreds - or in the case of Japan - more than 1000 years ago, so it can look outdated through a 21st century lens.
But it's enduring, and opinion polls suggest it can be popular. So what does monarchy mean in the modern age? Which royal families are not only surviving, but are expanding their spheres of power and influence, and why the newest "monarchies" in the USA, Russia and China are not even royal at all.
Presenter: Professor Ben Ansell
Producer: Ravi Naik
Editor: Damon Rose
Contributors:
Dr Craig Prescott, specialist in UK Constitutional Law, Royal Holloway, University of London
Adam Hanieh, MBI Jaber Chair of Middle East Studies and Professor in the Development Studies Department at SOAS, University of London.
Stacie Goddard, Betty Freyhof Johnson ’44 Professor of Political Science and Associate Provost, Wellesley College, Massachusetts.
Abe Newman, Professor and John Powers Chair in International Business Diplomacy, Director, BMW Center for German and European Studies, Georgetown University, Washington DC

As generative AI and Deepfake technology has progressed over the last decade, you could be forgiven for thinking that it's never been more difficult to try to work out what is authentic and what is fake.
The search for authenticity is not new. It's a task that's challenged humanity for hundreds of years. Forgers have always tried to pass off copies as great artworks, but it's not always clear when an artist was responsible for an entire painting or farmed out parts of the job to apprentices. A few well-known modern artists outsource all of the construction and manufacture of some of their works to skilled craftsmen and women.
Although the idea is theirs, does that make the final product somehow less than the genuine article?
Idiosyncrasies, perceived flaws or personal flourishes are often key indicators that show an image is authentic. We use those same tell-tale signs to judge the authenticity of another type of image: the one that politicians want to portray.
How important is it to be a politician who is seen as authentic by voters? How can we measure political authenticity? If someone is carefully crafting their image on social media, how real is it? And even if it is fake, do voters care, if they have been seduced by the illusion?
Presenter: Ben Ansell
Producer: Ravi Naik
Editors: Lisa Baxter and Nick Holland
Contributors:
Estelle Lovatt, FRSA. Art Critic, Writer and Lecturer.
Lone Sorensen, Associate Professor of Political Communication, University of Leeds
Nick Clarke, Professor of Political Geography, University of Southampton
Tracy Dennis Tiwary, Professor of Behavioural Neuroscience, Clinical Psychology and Developmental Psychology, at the City University of New York.
Rethink is a BBC co-production with the Open University.