David Quammen is an American science writer and journalist whose 2012 book Spillover: Animal Infections and the Next Human Pandemic analyses how zoonotic viruses, like Ebola and SARS, spread from reservoir animal hosts to other animals and on to humans. He joins host Amy Mullins to revisit the highly relevant research and ideas presented in his book in light of the COVID-19 pandemic. David explores some of the mysterious characteristics of zoonotic diseases, including how the Hendra and Ebola viruses can linger and be reactivated in a patient even once they have been cleared as healthy, as well as why bats are over-represented as transmitters and hosts of viruses. David also explains that when humans interfere with diverse ecosystems, they shake dormant viruses loose from their natural hosts and give them an opportunity to seize onto a new host – human beings. Viruses with a high intrinsic capacity for evolution, like coronavirus, are all the more likely to adapt to us and become our next diseases, epidemics and pandemics – a fact scientists had warned us about following the SARS outbreak in 2003.