Fascinating story told by Carl Zimmer, illustrated by yeast studies.

Scientists suspect that the first step towards a complex multicellular body like ours is for cells to evolve to live in primitive clumps. There may be a lot of advantages to living this way. It may be harder for a predator to eat you, for example. At the University of Minnesota, a team of scientists led by William Ratcliff and Michael Travisano figured out a way to create this kind of natural selection in a lab. As I reported last year in the New York Times, they were able to get yeast–which normally lives as single cells–to turn into simple multicellular clumps in a few weeks.