Humanity has invented many devices capable of performing diverse movements and mechanical work. All of these devices are macroscopic objects. Remarkably, however, every mechanical engine found in living nature is of molecular scale, no larger than 100 nm. Even to move an elephant or a whale, the Nature assembles complexes made of billions of such molecular motors instead of constructing a single large engine. We do not yet fully understand the advantages of this strategy, but one aspect is clear. Molecular motors utilize chemical energy to perform mechanical work, but they do not rely on elevated temperatures or pressures. Remarkably, the efficiency of these engines often greatly exceeds that of an internal combustion engine. Therefore, it is of great interest to understand how molecular motors function and how they have evolved. Among the most primitive molecular devices capable of moving molecular cargo are microtubules. Microtubules are ubiquitous cytoskeletal polymers that are critical for maintaining the cell’s shape and structure, its viability, and its proper functioning. Besides their structural roles, microtubules enable the separation of chromosomes during cell division — a key process for all life. Microtubule dynamics involve a biochemical stage in which the high-energy molecule GTP is hydrolyzed, and the released energy becomes stored in the strained conformation of the microtubule. Only recently has it become fully clear that this stored conformational energy can be harnessed by the cell to perform the work of separating and transporting sister chromosomes to the opposite cellular poles during cell division. This appears to be some of the most ancient molecular mechanochemical engines operating within the cell.