"In the world today, we face considerable challenges, and while new ones pile on, the old standbys of fossil fuel overuse, greenhouse gas emissions, resource scarcity, food security, and weather and water extremes like droughts and floods remain. Fortunately, scientists are studying myriad ways human waste can help. Science journalist Lina Zeldovich argues in The Other Dark Matter that human excrement is a resource, cheap and widely available, that...