All modern multicellular life — all life that any of us regularly see — is made of cells with a knack for compartmentalization. Recent discoveries are revealing how the first eukaryote got its start. The eukaryotes invented organization, if we use the literal definition of “organize”: to be furnished with organs. Kristina Armitage/Quanta Magazine Introduction Three billion years ago, life on Earth was simple. Single-celled organisms ruled, and there wasn’t much to them. They were what we now cal...