Author and conservationist Isabella Tree talks about her book Wilding with EconTalk host Russ Roberts. Tree and her husband decided to turn their three and a half acre farm, the Knepp Castle Estate, into something wilder, a place for wild ponies, wild pigs, wild oxen, and an ever-wider variety of birds and bugs. The conversation covers the re-wilding phenomenon, the complexity of natural systems, and the nature of emergent order.