We’re arriving at two thresholds, though, not one. In a world of single-celled aquatic life, we’ve seen how individuals can sense their surroundings and signal to others. But we’re about to look at the transition from single-celled life to many-celled life. Once that transition is under way, the signaling and sensing that connected one organism to another become the basis of new interactions which take place within the new forms of life now emerging. Sensing and signaling between organisms gives rise to sensing and signaling within an organism.
