Microbiomes are a multi-million-pound industry. Every week, many people send off poop samples to be examined so we can learn about our own ecosystems of bacteria, virus and fungi that live in our guts, with a view to improving health. But how accurate are these tests? Microbiologist Prof Jacques Ravel is calling for better controls in what is currently an unregulated industry. He joins us along with Prof Tim Spector, scientific co-founder of personalised nutrition app ZOE, to discuss the areas of concern, and potential benefits, of this direct-to-consumer model. Nobel prize-winning psychologist Daniel Kahneman has died at the age of 90. Widely acknowledged as one of the world's most influential psychologists, his many years of study centred on how and why we make the decisions we do. In 2011, his book Thinking, Fast and Slow, which summarizes much of his research, was published and became a best seller. We’re joined by presenter and author Claudia Hammond to unpick his legacy. The price of lab monkeys has plummeted. Used for drug development and testing, their value skyrocketed during the vaccine development period of the pandemic. But when the boom for vaccines died, the demand for (and value of) these monkeys plunged. Journalist Eleanor Olcott provides the full picture.  Are there alternatives to animal testing? Marnie visits a lab in Cambridge to find out about neural organoids, cellular clumps grown from stem cells made to replicate the brain. Developmental biologist Prof Madeline Lancaster shows her around and Dr Sarah Chan from the University of Edinburgh digs into the ethics of this cutting-edge branch of science.Presenter: Marnie Chesterton
Producers: Florian Bohr, Hannah Robins, Louise Orchard and Imaan Moin
Editor: Martin Smith
Production Co-ordinator: Jana Bennett-Holesworth  BBC Inside Science is produced in collaboration with the Open University.