Episode 6 of the Tartan Tardigrade, a podcast where scientists from the UK Centre for Astrobiology talk to guests from around the world about their research in astrobiology, their careers, and the prospects for life in the universe. In this episode we talk to Mark Van Zuilen from the Institut de Physique du Globe de Paris, who told us about their work on determining whether biosignatures we observe in the environment are truly produced by biology.