There are billions of people on this planet, and many of us love to eat meat. Can the demand be filled in a sustainable(可持续的) and affordable way? A bunch of businessmen are not only optimistic but are working to make this happen sooner than you may think.The environmental effects caused by meat consumption (食用)—waste, animal treatment, health problems and even the greenhouse gas effects that are potentially caused by methane gas produced by cows—have given rise to a number of startups(新兴公司)looking to develop meats in different ways.For example, San Francisco-based Memph