Podcast: A dirty space station, the benefits of singing, and more

Just how dirty is the International Space Station? Were saber-toothed cats able to take down giant mastodons? And could singing help you make friends? Science’s Online News Editor David Grimm and Susanne Bard discuss these stories and more. Plus, Science correspondent Lizzie Wade discusses whether the amazing biodiversity of the Amazon Basin was the result of massive flooding, or the uplift of the Andes mountain range.