Of course, previous generations of scientists have developed their own cool methods for answering these questions. But none of the methods is perfect. A human couldn't do such tracking without computer help, but even for a computer, it's difficult to keep tabs on thousands of moving, duplicating cells at once. In this latest work, a team of biologists from the Howard Hughes Medical Institute is releasing, for free, its method for recording embryotic development automatically. The technique is able to track up to 20,000 cells at once and is 97 percent accurate. The team has used it to watch the development of fruit fly, zebrafish and mouse embryos—basically, how these animals are built from the ground up. The idea is that animal species are similar enough that scientists are able to learn some basic principles about how humans develop by watching lab animals, using techniques it would be unethical to apply to a human embryo.