Is male testosterone in freefall?

Is male testosterone in freefall?

Men’s average testosterone levels have halved over the past 50 years, according to scientists who say society is facing a male fertility crisis. Rising levels of obesity and diabetes are expected to play a part, but the team behind the work suggest that environmental factors such as endocrine-disrupting chemicals – which can be found in various household items – and global heating could also be factors in the apparent striking decline. Ian Sample speaks to science correspondent Hannah Devlin to find out how the work has been received and what the researchers want to see happen in response to their finding. Help support our independent journalism at theguardian.com/sciencepod [https://www.theguardian.com/sciencepod]

‘A break from scrolling’: how Gen Z fell in love with birding

In the last 50 years, Britain has lost an astonishing 73 million wild birds from its landscape, according to the British Trust for Ornithology. Habitat loss, pesticides, disease, cats and the climate crisis mean there are fewer birds than ever before. For children and young people it can be difficult to appreciate the scale of the loss due to a psychological phenomenon called ‘shifting baseline syndrome’, where each generation inherits a degraded version of the environment, and therefore doesn’t notice the overall decline. But Gen Z are bucking the trend. Thanks to social media and the Merlin Bird ID app, birding has become cool. To find out what we’re missing from the dawn chorus, and why young people are embracing birdwatching, Madeleine Finlay hears from the writer Robert Macfarlane and from Jess Painter, a member of the RSPB’s youth council. Help support our independent journalism at theguardian.com/sciencepod [https://www.theguardian.com/sciencepod]

‘Beautiful blobs’: can scientists build life from scratch?

Researchers claim they are closer to creating life from nothing after building tiny, quivering blobs that use lab-made DNA to feed, grow and multiply in a dish. To find out how significant this step is, and where scientists hope it will lead, Madeleine Finlay hears from co-host Ian Sample and from Kate Adamala, professor of genetics at the University of Minnesota. Help support our independent journalism at theguardian.com/sciencepod [https://www.theguardian.com/sciencepod]

Reflecting pool algae: the science Trump needs to know

The Lincoln Memorial reflecting pool in Washington DC has hardly been out of the news since April when President Trump vowed to have it renovated, and painted ‘American flag blue’ by 4 July. Despite the pool being stripped, cleaned, coated and refilled, within days the algae that has plagued it for decades was back. To find out why these blooms happen, what makes them so difficult to tackle and what Trump could try next, Ian Sample hears from co-host Madeleine Finlay, and from Dr Linda May, a freshwater ecologist at the UK Centre for Ecology & Hydrology.. Help support our independent journalism at theguardian.com/sciencepod [https://www.theguardian.com/sciencepod]

Nature or nurture: can genes make us behave ‘badly’?

How much do our genes determine about our lives, and could they influence traits like risk-taking, antisocial behaviour or even violence? Ian Sample talks to Kathryn Paige Harden, a behavioural geneticist and professor of psychology at the University of Texas at Austin who studies how genetic factors shape human behaviour. In her book Original Sin she explores how nature and nurture combine to influence our likelihood of committing crimes, and asks whether the ‘cause’ of our actions matters for how we think about culpability. Help support our independent journalism at theguardian.com/sciencepod [https://www.theguardian.com/sciencepod]