What if we could turn back time and reverse extinction? Famed writer, biologist, and environmentalist Stewart Brand is attempting this with an organization he co-founded. Revive and Restore is building a tool kit for genetic restoration that would allow the rebirth of species, like the woolly mammoth. Brand says the absence of these animals has left a gap and reviving them will re-enrich the entire conservation world. There are other reasons to bring back certain species, like enhancing genetic diversity. But what about the ethical questions surrounding such a pursuit? Brand speaks with Flora Lichtman, science writer and host of Gimlet Media’s “Every Little Thing” podcast.