Emma Marris' first book, "Rambunctious Garden," was an iconoclastic look at how our rigid ideas of pristine nature are getting in the way of appreciating and conserving the nature all around us. I really enjoyed her first book, and I assign several chapters of it to my ecology undergraduates at UC Berkeley. I was excited to hear that Marris had finally come out with a second book, 10 years later.I was not disappointed. "Wild Souls" gets to the heart of many issues that have been troubling me as a scientist, a conservationist, an animal lover, and an amateur philosopher. The more I've thought about it over the years, the more convinced I become that our treatment of animals will come to be seen as one of the greatest moral failings of modern times. And yet, sometimes even when we think we are treating animals well, or trying to do the right thing, our efforts may backfire. Here are some examples of tough topics Marris tackles in "Wild Souls":- Building on her previous book, Marris discusses the ethical quandaries that can arise when we artificially insist on a strict division between "wild" and "domesticated," or "natural" and "human." She describes a case study of wild wolves interbreeding with domestic dogs (livestock guard dogs), in which there was an ensuing debate about whether the wolf hybrid pups should be tracked down and shot so they didn't contaminate the wolf gene pool. If it seems like the right answer is obviously yes, they should be shot, ask yourself: how would you explain to the mother wolf why you are shooting her pups? (If you shine a certain light on it, it begins to look analogous to some unsavory periods in human history.)- Although we think of zoos as being bastions of conservation biology, and cornerstones of public education about the natural world, in fact most zoos are nothing of the kind. Most zoos are simply there to attract customers and make money, even if they put on a veneer of "noble mission" to legitimize the fact that they are keeping animals in cages who really don't want to be in cages. Marris presents scathing evidence that zoo animals are, on the whole, miserable and serve no purpose other than to amuse and entertain us. I will never think about zoos in the same way again.- We may think it is obvious that an invasive species should be exterminated when it is threatening to harm a native species. But, Marris points out, species do not suffer: individuals do. Although the extinction of a rare island bird species is a major loss however you calculate it, is preventing that loss worth an unlimited amount of collateral damage? Is it worth the agonized death-by-poison of thousands or millions of rodents - who are on the island through no fault of their own? The rare birds do not know they are rare, and the common rats do not know they are common. They are all individuals with their own feelings, just as we are. In deciding that one species must live and the other must die, we are imposing our human framework, and when one tries to pin down the reasoning, it becomes surprisingly slippery.Marris takes this ad absurdium when she recounts an anecdote from New Zealand in which the government gave a suburban pet owner a hefty fine for failing to properly care for her rabbit, who needed veterinary attention. Meanwhile, on the other side of the backyard fence, thousands of wild rabbits were dying horrible deaths by government-sanctioned poison. Same exact species. Why do certain individuals deserve our care and others our contempt?"Wild Souls" raises at least as many questions as it offers answers. I finished the book wishing for more closure, which was not to be (these are difficult topics), but at least I felt as though I could articulate the important questions better. The book is packed with personal and professional anecdotes, thoroughly referenced science, engaging interviews, tales of adventure, and genuine emotion - because the whole reason we explore these questions is that we care about animals and about the living world.I highly recommend "Wild Souls" to anyone working in animal ecology or behavior, conservation biology, or environmental ethics. I also recommend it to any layperson who is interested in these topics, as it's very readable and doesn't require a technical background. You can bet that chapters from this book will be appearing on my ecology syllabus next year.(Photo: Cinder and Ash are glad that Marris considers rodents to be worthy of moral consideration.)