From the beginning of life, rivers experiment, trying new directions and invariably taking the easiest path. Everything follows the line of least resistance, a river, a vein cutting through rock, animals crossing a hillside, people on their way to work. As we go in search of some of the earliest life, passing through layers...

  It was early morning on the Coppermine River in Nunavut, Canada. A gentle mist rose from the surface of the glassy water, the sun’s first pink rays sparkling in the moving current. In the distance, the gurgling sound of faster flowing water was punctuated by birds waking in the trees, dragonflies chasing the buzz...