In a radical departure from the plant lineage, our ancestors—the Unikonts—simplified their propulsion system. They stopped using two “pulling” flagella and narrowed it down to a single motor. This made the cell more streamlined and paved the way for more specialized movement. While some Unikonts (like our cousins the Amoebas) eventually gave up on flagella altogether to “crawl” by oozing their bodies, our direct line stayed committed to the efficiency of the single-propeller design.