Francis Crick and James Watson made the greatest biological discovery of the 20th century when they solved the structure of DNA.  Photograph: Cold Spring Harbor Laboratory Archives/The New York Times

Everyone has heard of the seven wonders of the ancient world. Today I present my verdict on seven wonder discoveries in biological research, listed in(...)

 Stem cells are undifferentiated cells that can renew themselves through cell division and, under certain circumstances, can develop into differentiated organ-specific cells. Photograph: Getty Images

The human body is composed of about 37 trillion tiny units called cells, and there are about 200 different types of cells corresponding to the many di(...)