Sean Carroll in Preposterous Universe:
We’ve talked about the very origin of life, but certain transitions along its subsequent history were incredibly important. Perhaps none more so than the transition from unicellular to multicellular organisms, which made possible an incredible diversity of organisms and structures. Will Ratcliff studies the physics that constrains multicellular structures, examines the minute changes in certain yeast cells that allows them to become multicellular, and does long-term evolution experiments in which multicellularity spontaneously evolves and grows. We can’t yet create life from non-life, but we can reproduce critical evolutionary steps in the lab.