Trees and wildflowers blossom during all four seasons in Kunming, which is known as The City of Eternal Spring because of its year-round mild temperatures. However, it is also home to something much less natural: a laboratory where scientists have been creating monkey embryos with a mutated gene so that, when born, they will age unusually fast. Such experiments are done to study human diseases such as autism, cancer, Alzheimer's and muscular dystrophy.