How do you define a species? The question has been controversial since the days of Darwin. On this episode of The Quanta Podcast, host Samir Patel speaks with writer Marlowe Starling about how recent advances in genomics have both clarified and complicated the picture. This topic was covered in a recent story [https://www.quantamagazine.org/how-ecotypes-harbor-the-genetic-memory-of-a-species-past-20260521/] for Quanta Magazine.   Each week on The Quanta Podcast, Quanta Magazine editor in chief Samir Patel speaks with the people behind the award-winning publication to navigate through some of the most important and mind-expanding questions in science and math.