This is a nice research story where theory goes first, experiments prove the theory right and unveil new unforeseen features that are more interesting than the phenomenon originally addressed. The original motivation was an intriguing paradox, the fact that KIF1A, a motor that is particularly weak, inefficient and apparently infix for intracellular transport is in charge of one of the most demanding transport tasks in biology, namely the transport of large vesicles along neuronal axons over very long distances, and with the capacity to develop large forces to overcome obstacles in a particularly crowded environment.
It all started with the hypothesis, that the reason for the specificity of KIF1A had related to their collective properties.