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Will my salmon swim home?
CrowdScience
Oct 25, 2019

Crowdscience listeners Michael and Ricky have been walking a tributary of the River Thames in London, UK. They’ve noticed that there are loads of fish, which have only returned in recent years thanks to clean water initiatives. But what about salmon, they wonder? Could they one day return too? If they popped some salmon eggs in the river, would they return to spawn later on in their lives? Marnie Chesterton heads to Norway to find out whether it’s possible. There, she follows the life cycle of salmon, from birth to death and travels to the salmon’s spawning grounds, before following their path out to sea and beyond. She explores the science behind ‘natal homing’ - returning to the place of your birth in order to reproduce. It isn’t just confined to salmon. But how does it work? Marnie also learns to fish as she joins an active research project that's evaluating if escaped farmed salmon are threatening their wild counterparts by interbreeding. Could this stop salmon swimming home?

Back in the UK, Marnie finds out if all this Norwegian expertise could be transplanted to a river in London? Quite possibly, but it's not without its challenges, as the UK's Environmental Agency found out after attempting to re-introduce salmon into the River Thames.

Presenter: Marnie Chesterton Produced by Graihagh Jackson for the BBC World Service

(Photo: The mighty Wild Atlantic salmon travelling to spawning grounds in the Scottish highlands. Credit: Getty Images)

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Jun 26, 2026
Do animals care about the past?

“What separates humans from animals, is an interest in the past”. That’s a 900-year-old quote from a textbook that Nigerian listener Taiwo came across, and he wrote to CrowdScience to ask if modern science would agree.

Most of us spend time thinking about the past, whether it is nostalgia for a bygone age or just wondering where we put the house keys yesterday. But is that just a human activity or do other animals also ruminate on their history and use it to make decisions? Taiwo wants to know if there is any evidence to show that animals have an interest in the past and if it matters to them.

Presenter Caroline Steel has a history of answering questions like this, so she sets out to find an answer. She meets researchers who have found evidence that animals not only remember past events, but use their memory for planning.

She talks to neuroscientist Dr Freyja Olafsdottir and discovers that some animals, including rats and mice, have the same brain structure for memory as humans.

She meets baby magpies in Professor Nicola Clayton’s laboratory in the UK and finds out about some of the very smart tactics jays use to hide their food from rivals, evidence that they’re using their memory to protect their interests.

She talks to psychologist Dr Gema Martin-Ordas whose research has shown that chimpanzees not only remember past events, but use what they’ve learnt in the future.

And she tests the memory of her own cat Oli, wondering if his ability to remember dinner time suggests that he is interested in the past too.

Ultimately it comes down to questions of consciousness, so as Caroline grapples with the idea that we can’t even be certain that other humans are genuinely conscious, what hope do we have of finding an answer for Taiwo?

Presenter: Caroline Steel

Producer: Jo Glanville

Editor: Ben Motley

(Photo: Cute clever cat with glasses reading a book. The cat lies on a stack of old books on a blue background. Credit:vvvita/Getty Images)


26min 28sec



Jun 5, 2026
Do plants have personalities?

CrowdScience listener George is showing Alex Lathbridge around a small, dark, and extremely hot shed, just outside the city of Accra in Ghana. Inside are row after row of shelves, stacked high with bulging grow-bags. And out of some of them, gorgeous cascades of oyster mushrooms are bursting into bloom.

We’re on George’s mushroom farm, and he’s noticed something interesting. Even though the conditions in his grow-shed are tightly controlled – they have exactly the same food, water, and light as each other – nevertheless, they respond differently. Some are more vigorous than others, some bloom quicker, others last longer, and some are more tolerant when the conditions change. And this got George wondering. Could ‘brainless’ lifeforms like mushrooms, and plants, have different ‘personalities’? Do they experience the world differently, and live their lives differently from each other? Alex Lathbridge is on the case.

He visits the PGRRI, the Plant Genetic Resources Research Centre, for a quick lesson on genetic variation in the plant world. Plants are all different at the genetic level, and it’s those differences which can result in a tastier fruit, or a hardier crop. But would we call traits like these personality?

In the Minimal Intelligence Lab in the University of Murcia in Spain, Paco Calvo thinks that we absolutely should. He studies plant intelligence, and points Alex to a whole host of examples of plants being smart in ways which might surprise you. Each one is an individual, and if we can only slow down enough to appreciate them properly, we’d be able to understand them better too.

Back in Ghana, Alex meets plant physiologist Dr Acheampong Atta-Boateng, in the beautiful grounds of Aburi Botanical Gardens, to meet some of these plants for himself. And he discovers that there’s a whole world of smart, resilient, and resourceful little organisms in the plant world, full of personality, if you know where to look. Who needs a brain!?

Presenter: Alex Lathbridge

Producer: Emily Knight

Editor: Ben Motley

(Photo: Drawing of a face and smiling eyes on a sunflower flower - stock photo- Credit: Jose A. Bernat Bacete via Getty Images)


29min 16sec

Will my salmon swim home?

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