How do you define "nature?" If we define it as that which is untouched by humans, then we won't have any left, says environmental writer Emma Marris. She urges us to consider a new definition of nature -- one that includes not only pristine wilderness but also the untended patches of plants growing in urban spaces -- and encourages us to bring o...

Human activity is affecting the planet in dramatic, unsustainable ways -- including destroying the habitats of wild animals. Considering our obligation to care for the creatures we've impacted, environmental writer Emma Marris dives into the ethics of wildlife management, zoos and aquariums, offering her thoughts on how we can help Earth's wildl...