G Wang

Every drop of blood hides founder cells that spend a lifetime churning out red blood cells, white blood cells, and platelets. With age, their work goes off the rails: immunity weakens, the risk of blood cancer rises. To see exactly how these cells deteriorate, scientists assembled an atlas of 186,000 blood stem cells from 28 healthy donors, from six weeks after conception to 74 years old.

The alfalfa root is studded with pink bumps the size of peas. Inside each one, bacteria turn nitrogen from the air into fertilizer, and the plant pays them back in sugar. To keep the deal from falling apart, the partners exchange protein messages, but until recently this conversation was almost inaudible to us.