Just under your skin lie whole aqueous worlds, where trillions of cells spark and beat and wriggle and secrete, doing all the complicated tasks of keeping you alive. They all share the same genetic code. But what they do with it is the difference between a neuron and a twitching muscle fiber.
Starting about a decade ago, a group of scientists began conducting a cellular census of every tissue in the human body to find out what cells actually live there, using a powerful new technology called single-cell RNA sequencing. It illuminates which parts of the genome a cell uses to conduct its unique task. The international collaborative effort, called the Human Cell Atlas, has since grown to include more than 2,000 researchers from 83 countries. And on Thursday, they reported a major feat: the creation of detailed maps of more than a million cells across 33 organs.