Asymmetry plays a major role in biology at every scale: think of DNA spirals, the fact that the human heart is positioned on the left, our preference to use our left or right hand … A team from the Institute of biology Valrose (CNRS/Inserm/Université Côte d’Azur), in collaboration with colleagues from the University of Pennsylvania, has shown how a single protein induces a spiral motion in another molecule. Through a domino effect, this causes cells, organs, and indeed the entire body to twist, triggering lateralized behaviour. This research is published in the journal Science on November 23, 2018.